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1. Shard Calculation

Query:

Response:

Calculated Shard: 152 (from laksa087)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa152.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat\')), getAhrefsUnparsedNoserviceFromURL(\'https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat","crawl_time":1775570629,"first_indexed_time":1375986950,"http_code":200,"src_unparsed":"org,wikipedia!en,\/wiki\/Schr%C3%B6dinger%27s_cat s443","src_root_hash":"17790707453426894952","history_drop_reason":null,"meta_title":"Schrödinger's cat - Wikipedia","meta_descriptions":[],"attrs_boilerpipe_text":"Schrödinger's cat: a cat, a flask of poison, and a\nradioactive\nsource connected to a\nGeiger counter\nare placed in a sealed box. As illustrated, the quantum description uses a superposition of an alive cat and one that has died.\nIn\nquantum mechanics\n,\nSchrödinger's cat\nis a\nthought experiment\nconcerning\nquantum superposition\n. In the thought experiment, a hypothetical\ncat\nin a closed box may be considered to be simultaneously both alive and dead while it is unobserved, as a result of its fate being linked to a random\nsubatomic\nevent that may or may not occur. This experiment, viewed this way, is described as a\nparadox\n. This thought experiment was devised by physicist\nErwin Schrödinger\nin 1935,\n[\n1\n]\nin a discussion with\nAlbert Einstein\n,\n[\n2\n]\nto illustrate what Schrödinger saw as the problems of\nNiels Bohr\nand\nWerner Heisenberg\n's philosophical views on quantum mechanics.\nIn Schrödinger's original formulation, a cat, a flask of poison, and a\nradioactive\nsource are placed in a sealed box. If an internal radiation monitor such as a\nGeiger counter\ndetects radioactivity (a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. If no decaying atom triggers the monitor, the cat remains alive. Mathematically, the\nwave function\nthat describes the contents of the box is a combination, or\nquantum superposition\n, of these two possibilities. Yet, when one looks in the box, one sees the cat\neither\nalive\nor\ndead, not both alive\nand\ndead. This poses the question of when exactly quantum superposition ends and reality resolves into one possibility or the other.\nAlthough originally a critique of Bohr and Heisenberg, Schrödinger's seemingly paradoxical thought experiment became part of the foundation of quantum mechanics. It is often featured in theoretical discussions of the\ninterpretations of quantum mechanics\n, particularly in situations involving the\nmeasurement problem\n. As a result, Schrödinger's cat has had enduring\nappeal in popular culture\n. The experiment is not intended to be actually performed on a cat, but rather as an easily understandable illustration of the behavior of atoms. Experiments at the atomic scale have been carried out, showing that very small objects may exist as superpositions, but superposing an object as large as a cat would pose considerable technical difficulties.\n[\n3\n]\nFundamentally, the Schrödinger's cat experiment asks how long quantum superpositions last and when (or whether) they collapse. Different\ninterpretations of the mathematics of quantum mechanics\nhave been proposed that give different explanations for this process.\nOrigin and motivation\nUnsolved problem in physics\nHow does the quantum description of reality, which includes elements such as the superposition of states and wavefunction collapse or quantum decoherence, give rise to the reality we perceive? Another way of stating this question regards the measurement problem: What constitutes a \"measurement\" that apparently causes the wave function to collapse into a definite state?\nSchrödinger intended his thought experiment as a discussion of the\nEPR article\n—named after its authors\nEinstein\n,\nPodolsky\n, and\nRosen\n—in 1935.\n[\n4\n]\n[\n5\n]\nThe EPR article highlighted the counterintuitive nature of\nquantum superpositions\n, in which a quantum system for two particles does not separate\n[\n6\n]\n: 150 \neven when the particles are detected far from their last point of contact. The EPR paper concludes with a claim that this lack of separability meant that quantum mechanics as a theory of reality was incomplete.\nSchrödinger and Einstein exchanged letters about Einstein's EPR article, in the course of which Einstein pointed out that the  state of an\nunstable\nkeg of\ngunpowder\nwill, after a while, contain a superposition of both exploded and unexploded states.\n[\n5\n]\nTo further illustrate, Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition.  He proposed a scenario with a cat in a closed steel chamber, wherein the cat's life or death depended on the state of a\nradioactive\natom, whether it had decayed and emitted radiation or not. According to Schrödinger, the position taken by Bohr and Heisenberg would be that\nthe cat remains both alive and dead\nuntil the state has been observed. Schrödinger did not wish to promote the idea of dead-and-live cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics,\n[\n1\n]\nthus employing\nreductio ad absurdum\n.\nSince Schrödinger's time, various\ninterpretations of the mathematics of quantum mechanics\nhave been advanced by physicists, some of which regard the \"alive and dead\" cat superposition as quite real, while others do not.\n[\n7\n]\n[\n8\n]\nIntended as a critique of ideas prevalent in 1935, the Schrödinger's cat thought experiment remains a\ntouchstone\nfor modern interpretations of quantum mechanics and can be used to illustrate and compare their strengths and weaknesses.\n[\n9\n]\n[\nbetter source needed\n]\nThought experiment\nA life-size cat figure in the garden of Huttenstrasse 9, Zurich, where\nErwin Schrödinger\nlived from 1921 to 1926. Depending on the light conditions, the figure appears to be either a live cat or a dead one.\nSchrödinger wrote:\n[\n1\n]\n[\n10\n]\nOne can contrive even completely burlesque [farcical] cases. A cat is put in a steel chamber along with the following infernal device (which must be secured against direct interference by the cat): in a\nGeiger counter\n, there is a tiny amount of radioactive substance, so tiny that in the course of an hour one of the atoms will perhaps decay, but also, with equal probability, that none of them will; if it does happen, the counter tube will discharge and through a relay release a hammer that will shatter a small flask of\nhydrocyanic acid\n. If one has left this entire system to itself for an hour, one would tell oneself that the cat is still alive if no atom has\ndecayed\nin the meantime. Even a single atomic decay would have poisoned it. The\npsi-function\nof the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or spread out in equal parts.\nIt is typical of these cases that an indeterminacy originally restricted to the atomic domain turns into a sensually observable [macroscopic] indeterminacy, which can then be resolved by direct observation. This prevents us from so naïvely accepting a \"blurred model\" as representative of reality. Per se, it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks.\nSchrödinger developed his famous\nthought experiment\nin correspondence with Einstein. He suggested this 'quite ridiculous case' to illustrate his conclusion that the wave function cannot represent reality.\n[\n6\n]\n: \n153\n \nThe wave function description of the complete cat system implies that the reality of the cat mixes the living and dead cat.\n[\n6\n]\n: 154 \nEinstein was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote:\n[\n6\n]\n: 157 \nYou are the only contemporary physicist, besides\nLaue\n, who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gun powder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation.\n[\n11\n]\nNote that the charge of gunpowder is not mentioned in Schrödinger's setup, which uses a Geiger counter as an amplifier and hydrocyanic poison instead of gunpowder. The gunpowder had been mentioned in Einstein's original suggestion to Schrödinger 15 years before, and Einstein carried it forward to the present discussion.\n[\n5\n]\nAnalysis\nIn modern terms Schrödinger's hypothetical cat experiment describes the\nmeasurement problem\n: quantum theory describes the cat system as a combination of two possible outcomes but only one outcome is ever observed.\n[\n12\n]\n: \n57\n \n[\n13\n]\n: \n1269\n \nThe experiment poses the question, \"\nwhen\ndoes a quantum system stop existing as a superposition of states and become one or the other?\"  (More technically, when does the actual quantum state stop being a non-trivial\nlinear combination\nof states, each of which resembles different classical states, and instead begin to have a unique classical description?) Standard microscopic quantum mechanics describes multiple possible outcomes of experiments but only one outcome is observed. The thought experiment illustrates this apparent paradox. Our intuition says that the cat cannot be in more than one state simultaneously—yet the quantum mechanical description of the thought experiment requires such a condition.\nInterpretations\nSince Schrödinger's time, other interpretations of quantum mechanics have been proposed that give different answers to the questions posed by Schrödinger's cat of how long superpositions last and when (or\nwhether\n) they collapse.\nCopenhagen interpretation\nA commonly held interpretation of quantum mechanics is the Copenhagen interpretation.\n[\n14\n]\nIn the Copenhagen interpretation, a measurement results in only one state of a superposition. This thought experiment makes apparent the fact that this interpretation simply provides no explanation for the state of the cat while the box is closed. The wavefunction description of the system consists of a superposition of the states \"decayed nucleus\/dead cat\" and \"undecayed nucleus\/living cat\". Only when the box is opened and observed can we make a statement about the cat.\n[\n6\n]\n: \n157\n \nRole of consciousness\nIn 1932,\nJohn von Neumann\ndescribed in his book\nMathematical Foundations of Quantum Mechanics\na pattern where the radioactive source is observed by a device, which itself is observed by another device and so on. It makes no difference in the predictions of quantum theory where along this chain of causal effects the superposition collapses.\n[\n15\n]\nThis potentially infinite chain could be broken if the last device is replaced by a conscious observer. This solved the problem because it was claimed that an individual's consciousness cannot be multiple.\n[\n16\n]\nEugene Wigner asserted that an observer is necessary for a collapse to one or the other (e.g., either a live cat or a dead cat) of the terms on the right-hand side of a\nwave function\n. Wigner discussed the interpretation in a thought experiment known as\nWigner's friend\n.\n[\n17\n]\nWigner supposed that a friend opened the box and observed the cat without telling anyone. From Wigner's conscious perspective, the friend is now part of the wave function and has seen a live cat and seen a dead cat. To a third person's conscious perspective, Wigner himself becomes part of the wave function once Wigner learns the outcome from the friend. This could be extended indefinitely.\n[\n17\n]\nA resolution of the paradox is that the triggering of the Geiger counter counts as a measurement of the state of the radioactive substance. Because a measurement has already occurred deciding the state of the cat, the subsequent observation by a human records only what has already occurred.\n[\n18\n]\nAnalysis of an actual experiment by\nRoger Carpenter\nand A. J. Anderson found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before any human knows of the result.\n[\n19\n]\nThe apparatus indicates one of two colors depending on the outcome. The human observer sees which color is indicated, but does not consciously know which outcome the color represents. A second human, the one who set up the apparatus, is told of the color and becomes conscious of the outcome, and the box is opened to check if the outcome matches.\n[\n15\n]\nHowever, it is disputed whether merely observing the color counts as a conscious observation of the outcome.\n[\n20\n]\nBohr's interpretation\nAnalysis of the work of\nNiels Bohr\n, one of the main scientists associated with the Copenhagen interpretation, suggests he viewed the state of the cat before the box is opened as indeterminate. The superposition itself had no physical meaning to Bohr: Schrödinger's cat would be either dead or alive long before the box is opened but the cat and box form an inseparable combination.\n[\n21\n]\nBohr saw no role for a human observer.\n[\n22\n]\n: 35 \nBohr emphasized the classical nature of measurement results.\nAn \"irreversible\" or effectively irreversible process imparts the classical behavior of \"observation\" or \"measurement\".\n[\n23\n]\n[\n24\n]\n[\n25\n]\nMany-worlds interpretation\nThe quantum-mechanical \"Schrödinger's cat\" paradox according to the many-worlds interpretation. In this interpretation, every event is a branch point. The cat is both alive and dead—regardless of whether the box is opened—but the \"alive\" and \"dead\" cats are in different branches of the universe that are equally real but cannot interact with each other.\nIn 1957,\nHugh Everett\nformulated the many-worlds interpretation of quantum mechanics, which does not single out observation as a special process. In the many-worlds interpretation, both alive and dead states of the cat persist after the box is opened, but are\ndecoherent\nfrom each other. In other words, when the box is opened, the observer and the possibly-dead cat split into an observer looking at a box with a dead cat and an observer looking at a box with a live cat. But since the dead and alive states are decoherent, there is no communication or interaction between them.\nWhen opening the box, the observer becomes entangled with the cat, so \"observer states\" corresponding to the cat's being alive and dead are formed; each observer state is\nentangled\n, or linked, with the cat so that the observation of the cat's state and the cat's state correspond with each other.  Quantum decoherence ensures that the different outcomes have no interaction with each other. Decoherence is generally considered to prevent simultaneous observation of multiple states.\n[\n26\n]\n[\n27\n]\nA variant of the Schrödinger's cat experiment, known as the\nquantum suicide\nmachine, has been proposed by cosmologist\nMax Tegmark\n. It examines the Schrödinger's cat experiment from the point of view of the cat, and argues that by using this approach, one may be able to distinguish between the Copenhagen interpretation and many-worlds.\n[\ncitation needed\n]\nEnsemble interpretation\nIn\nEnsemble interpretations\n, superpositions are sub-ensembles of a larger statistical ensemble. The state vector would not apply to individual cat experiments, but only to the statistics of many similarly prepared cat experiments. Proponents of these interpretations argue that this makes the Schrödinger's cat paradox a trivial matter, or a non-issue. When the physicist opens the box, they simply discover which subensemble that specific cat belonged to.\n[\n28\n]\nRelational interpretation\nThe\nrelational interpretation\nmakes no fundamental distinction between the human experimenter, the cat, and the apparatus or between animate and inanimate systems; all are quantum systems governed by the same rules of wavefunction\nevolution\n, and all may be considered \"observers\". But the relational interpretation allows that different observers can give different accounts of the same series of events, depending on the information they have about the system.\n[\n29\n]\n[\nnon-primary source needed\n]\nThe cat can be considered an observer of the apparatus; meanwhile, the experimenter can be considered another observer of the system in the box (the cat plus the apparatus). Before the box is opened, the cat, by nature of its being alive or dead, has information about the state of the apparatus (the atom has either decayed or not decayed); but the experimenter does not have information about the state of the box contents. In this way, the two observers simultaneously have different accounts of the situation: To the cat, the wavefunction of the apparatus has appeared to \"collapse\"; to the experimenter, the contents of the box appear to be in superposition. Not until the box is opened, and both observers have the same information about what happened, do both system states appear to \"collapse\" into the same definite result, a cat that is either alive or dead.\n[\ncitation needed\n]\nTransactional interpretation\nIn the\ntransactional interpretation\nthe apparatus emits an advanced wave backward in time, which combined with the wave that the source emits forward in time, forms a standing wave. The waves are seen as physically real, and the apparatus is considered an \"observer\". In the transactional interpretation, the collapse of the wavefunction is \"atemporal\" and occurs along the whole transaction between the source and the apparatus.  The cat is never in superposition.  Rather the cat is only in one state at any particular time, regardless of when the human experimenter looks in the box. The transactional interpretation resolves this quantum paradox.\n[\n30\n]\n[\nnon-primary source needed\n]\nObjective collapse theories\nAccording to\nobjective collapse theories\n, superpositions are destroyed spontaneously (irrespective of external observation) when some objective physical threshold (of time, mass, temperature,\nirreversibility\n, etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is opened. This could loosely be phrased as \"the cat observes itself\" or \"the environment observes the cat\".\nObjective collapse theories require a modification of standard quantum mechanics to allow superpositions to be destroyed by the process of time evolution.\n[\n31\n]\nThese theories could ideally be tested by creating mesoscopic superposition states in the experiment. For instance, energy cat states have been proposed as a precise detector of the quantum gravity related energy decoherence models.\n[\n32\n]\nApplications and tests\nSchrödinger's cat quantum superposition of states and effect of the environment through decoherence\nThe experiment as described is a purely theoretical one, and the machine proposed is not known to have been constructed. However, successful experiments involving similar principles, e.g. superpositions of\nrelatively large\n(by the standards of quantum physics) objects have been performed.\n[\n33\n]\n[\nbetter source needed\n]\nThese experiments do not show that a cat-sized object can be superposed, but the known upper limit on \"\ncat states\n\" has been pushed upwards by them. In many cases the state is short-lived, even when cooled to near\nabsolute zero\n.\nA \"cat state\" has been achieved with photons.\n[\n34\n]\n[\n35\n]\nA beryllium ion has been trapped in a superposed state.\n[\n36\n]\nAn experiment involving a\nsuperconducting quantum interference device\n(\"SQUID\") has been linked to the theme of the thought experiment: \"The superposition state does not correspond to a billion electrons flowing one way and a billion others flowing the other way. Superconducting electrons move en masse. All the superconducting electrons in the SQUID flow both ways around the loop at once when they are in the Schrödinger's cat state.\"\n[\n37\n]\nA\npiezoelectric\n\"tuning fork\" has been constructed, which can be placed into a superposition of vibrating and non vibrating states. The resonator comprises about 10 trillion atoms.\n[\n38\n]\nAn experiment involving a flu virus has been proposed.\n[\n39\n]\nAn experiment involving a bacterium and an electromechanical oscillator has been proposed.\n[\n40\n]\nIn\nquantum computing\nthe phrase \"cat state\" sometimes refers to the\nGHZ state\n, wherein several qubits are in an equal superposition of all being 0 and all being 1; e.g.,\nAccording to at least one proposal, it may be possible to determine the state of the cat\nbefore\nobserving it.\n[\n41\n]\n[\n42\n]\nIn popular culture\nThis drawing by\nF. Gwynplaine MacIntyre\n, originally published in\nAnalog\nmagazine, illustrates MacIntyre's science-fiction story \"Schrödinger's Cat-Sitter\". The cat is depicted simultaneously in front of and behind the\nimpossible trident\nin an\noptical illusion\n.\nAccording to historian of science\nRobert P. Crease\n, Schrödinger's thought experiment did not become widely known until the 1970s. In 1972\nUrsula K. Le Guin\nlearned about it while researching quantum mechanics for her novel\nThe Dispossessed\n; Crease credits her 1974 short story \"Schrödinger's Cat\" with bringing the concept into popular culture.\n[\n43\n]\nOther\nscience-fiction\nwriters soon picked it up, often using it in a humorous vein.\n[\n44\n]\nWorks of fiction have employed Schrödinger's thought experiment as plot device and as\nmetaphor\n, in genres from\napocalyptic science fiction\nto young-adult drama, making the cat more prominent in popular culture than in physics itself.\n[\n45\n]\n[\n46\n]\n[\n47\n]\n[\n48\n]\nSchrödinger's cat has been a motive in many science fiction works, and used as a title of a number of them, including\nGreg Bear\n's \"Schrödinger's Plague\" (\nAnalog\n, 29 March 1982),\nGeorge Alec Effinger\n's \"\nSchrödinger's Kitten\n\" (\nOmni\n, September 1988),\nF. Gwynplaine MacIntyre\n's \"Schrödinger's Cat-Sitter\" (\nAnalog\n, July\/August 2001),\nRudy Rucker\n's \"Schrödinger's Cat\" (\nAnalog\n, 30 March 1981), and\nRobert Anton Wilson\n's\nSchrödinger's Cat Trilogy\n(1988), illustrating various\ninterpretations of quantum physics\n.\n[\n49\n]\n[\n50\n]\nIn addition to novels and short stories, Schrödinger's cat has appeared in film,\n[\n51\n]\n[\n52\n]\n[\n53\n]\n[\n54\n]\npoetry,\n[\n55\n]\n[\n56\n]\ntheatre,\n[\n57\n]\n[\n58\n]\nlive-action television,\n[\n59\n]\ncartoons,\n[\n60\n]\n[\n61\n]\n[\n62\n]\nmusic,\n[\n63\n]\nand webcomics.\n[\n45\n]\nSee also\nBasis function\nCat state\nComplementarity (physics)\nDouble-slit experiment\nElitzur–Vaidman bomb tester\nHeisenberg cut\nModal realism\nObserver effect (physics)\nRay cat\nSchroedinbug\nReferences\n^\na\nb\nc\nSchrödinger, Erwin\n(November 1935). \"Die gegenwärtige Situation in der Quantenmechanik (The Present Situation in Quantum Mechanics)\".\nNaturwissenschaften\n.\n23\n(48):\n807–\n812.\nBibcode\n:\n1935NW.....23..807S\n.\ndoi\n:\n10.1007\/BF01491891\n.\nS2CID\n \n206795705\n.\nMan kann auch ganz burleske Fälle konstruieren. Eine Katze wird in eine Stahlkammer gesperrt, zusammen mit folgender Höllenmaschine (die man gegen den direkten Zugriff der Katze sichern muß): in einem Geigerschen Zählrohr befindet sich eine winzige Menge radioaktiver Substanz, so wenig, daß im Laufe einer Stunde vielleicht eines von den Atomen zerfällt, ebenso wahrscheinlich aber auch keines; geschieht es, so spricht das Zählrohr an und betätigt über ein Relais ein Hämmerchen, das ein Kölbchen mit Blausäure zertrümmert. Hat man dieses ganze System eine Stunde lang sich selbst überlassen, so wird man sich sagen, daß die Katze noch lebt, wenn inzwischen kein Atom zerfallen ist. Der erste Atomzerfall würde sie vergiftet haben. Die Psi-Funktion des ganzen Systems würde das so zum Ausdruck bringen, daß in ihr die lebende und die tote Katze (s.v.v.) [sit venia verbo] zu gleichen Teilen gemischt oder verschmiert sind. Das Typische an solchen Fällen ist, daß eine ursprünglich auf den Atombereich beschränkte Unbestimmtheit sich in grobsinnliche Unbestimmtheit umsetzt, die sich dann durch direkte Beobachtung entscheiden läßt. Das hindert uns, in so naiver Weise ein \"verwaschenes Modell\" als Abbild der Wirklichkeit gelten zu lassen. An sich enthielte es nichts Unklares oder Widerspruchsvolles. Es ist ein Unterschied zwischen einer verwackelten oder unscharf eingestellten Photographie und einer Aufnahme von Wolken und Nebelschwaden.\n^\nFine, Arthur\n.\n\"The Einstein-Podolsky-Rosen Argument in Quantum Theory\"\n.\nStanford Encyclopedia of Philosophy\n. Retrieved\nJune 11,\n2020\n.\n^\nBall, Philip\n(June 25, 2018).\n\"Real-Life Schrödinger's Cats Probe the Boundary of the Quantum World\"\n.\nQuanta Magazine\n. Archived from\nthe original\non February 28, 2025\n. Retrieved\nFebruary 24,\n2025\n.\n^\nEinstein, A.; Podolsky, B.; Rosen, N. (May 15, 1935). \"Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?\".\nPhysical Review\n.\n47\n(10):\n777–\n780.\ndoi\n:\n10.1103\/PhysRev.47.777\n.\nISSN\n \n0031-899X\n.\n^\na\nb\nc\nFine, Arthur (2017).\n\"The Einstein-Podolsky-Rosen Argument in Quantum Theory\"\n.\nStanford Encyclopedia of Philosophy\n. Stanford University\n. Retrieved\nApril 11,\n2021\n.\n^\na\nb\nc\nd\ne\nBaggott, J. E. (2013).\nThe quantum story: a history in 40 moments\n(Impression: 3 ed.). Oxford: Oxford Univ. Press.\nISBN\n \n978-0-19-965597-7\n.\n^\nPolkinghorne, J. C. (1985).\nThe Quantum World\n.\nPrinceton University Press\n. p. 67.\nISBN\n \n0-691-02388-3\n.\nArchived\nfrom the original on May 19, 2015\n. Retrieved\nNovember 20,\n2020\n.\n^\nTetlow, Philip (2012).\nUnderstanding Information and Computation: From Einstein to Web Science\n. Gower Publishing, Ltd. p. 321.\nISBN\n \n978-1-4094-4040-6\n.\nArchived\nfrom the original on May 19, 2015.\n^\nLazarou, Dimitris (2007). \"Interpretation of quantum theory - An overview\".\narXiv\n:\n0712.3466\n[\nquant-ph\n].\n^\nTrimmer, John D. (1980). \"The Present Situation in Quantum Mechanics: A Translation of Schrödinger's \"Cat Paradox\" Paper\".\nProceedings of the American Philosophical Society\n.\n124\n(5):\n323–\n338.\nJSTOR\n \n986572\n.\nThe English translation here is based on the German original, not on the inaccurate version in this source's translation of the entire article:\nSchrödinger: \"The Present Situation in Quantum Mechanics.\" 5. Are the Variables Really Blurred?\n^\nMaxwell, Nicholas (January 1, 1993). \"Induction and Scientific Realism: Einstein versus van Fraassen Part Three: Einstein, Aim-Oriented Empiricism and the Discovery of Special and General Relativity\".\nThe British Journal for the Philosophy of Science\n.\n44\n(2):\n275–\n305.\ndoi\n:\n10.1093\/bjps\/44.2.275\n.\nJSTOR\n \n687649\n.\n^\nPeres, Asher\n(January 1988).\n\"Schrödinger's immortal cat\"\n.\nFoundations of Physics\n.\n18\n(1):\n57–\n76.\nBibcode\n:\n1988FoPh...18...57P\n.\ndoi\n:\n10.1007\/BF01882873\n.\nISSN\n \n0015-9018\n.\n^\nSchlosshauer, Maximilian (February 23, 2005).\n\"Decoherence, the measurement problem, and interpretations of quantum mechanics\"\n.\nReviews of Modern Physics\n.\n76\n(4):\n1267–\n1305.\narXiv\n:\nquant-ph\/0312059\n.\nBibcode\n:\n2004RvMP...76.1267S\n.\ndoi\n:\n10.1103\/RevModPhys.76.1267\n.\n^\nWimmel, Hermann (1992).\nQuantum physics & observed reality: a critical interpretation of quantum mechanics\n. World Scientific. p. 2.\nISBN\n \n978-981-02-1010-6\n.\nArchived\nfrom the original on May 20, 2013\n. Retrieved\nMay 9,\n2011\n.\n^\na\nb\nHobson, Art (2017).\nTales of the Quantum: Understanding Physics' Most Fundamental Theory\n. New York, NY: Oxford University Press. pp. \n200–\n202.\nISBN\n \n978-0-19-067963-7\n. Retrieved\nApril 8,\n2022\n.\n^\nOmnès, Roland\n(1999).\nUnderstanding Quantum Mechanics\n. Princeton, New Jersey: Princeton University Press. pp. \n60–\n62.\nISBN\n \n0-691-00435-8\n. Retrieved\nApril 8,\n2022\n.\n^\na\nb\nLevin, Frank S. (2017).\nSurfing the Quantum World\n. New York, NY: Oxford University Press. pp. \n229–\n232.\nISBN\n \n978-0-19-880827-5\n. Retrieved\nApril 8,\n2022\n.\n^\nPuri, Ravinder R. (2017).\nNon-Relativistic Quantum Mechanics\n. Cambridge, United Kingdom: Cambridge University Press. p. 146.\nISBN\n \n978-1-107-16436-9\n. Retrieved\nApril 8,\n2022\n.\n^\nCarpenter RHS; Anderson AJ (2006).\n\"The death of Schrödinger's cat and of consciousness-based wave-function collapse\"\n(PDF)\n.\nAnnales de la Fondation Louis de Broglie\n.\n31\n(1):\n45–\n52. Archived from\nthe original\n(PDF)\non November 30, 2006\n. Retrieved\nSeptember 10,\n2010\n.\n^\nOkón E, Sebastián MA (2016). \"How to Back up or Refute Quantum Theories of Consciousness\".\nMind and Matter\n.\n14\n(1):\n25–\n49.\n^\nFaye, J\n(January 24, 2008).\n\"Copenhagen Interpretation of Quantum Mechanics\"\n.\nStanford Encyclopedia of Philosophy\n. The Metaphysics Research Lab Center for the Study of Language and Information,\nStanford University\n. Retrieved\nSeptember 19,\n2010\n.\n^\nJohn Bell\n(1990). \"Against 'measurement'\n\".\nPhysics World\n.\n3\n(8):\n33–\n41.\ndoi\n:\n10.1088\/2058-7058\/3\/8\/26\n.\n^\nNiels Bohr\n(1985) [May 16, 1947]. Jørgen Kalckar (ed.).\nFoundations of Quantum Physics I (1926-1932)\n. Niels Bohr: Collected Works. Vol. 6. pp. \n451–\n454.\n^\nStig Stenholm (1983). \"To fathom space and time\". In\nPierre Meystre\n(ed.).\nQuantum Optics, Experimental Gravitation, and Measurement Theory\n. Plenum Press. p. 121.\nThe role of irreversibility in the theory of measurement has been emphasized by many. Only this way can a permanent record be obtained. The fact that separate pointer positions must be of the asymptotic nature usually associated with irreversibility has been utilized in the measurement theory of Daneri, Loinger and Prosperi (1962). It has been accepted as a formal representation of Bohr's ideas by Rosenfeld (1966).\n^\nHaake, Fritz (April 1, 1993). \"Classical motion of meter variables in the quantum theory of measurement\".\nPhysical Review A\n.\n47\n(4):\n2506–\n2517.\nBibcode\n:\n1993PhRvA..47.2506H\n.\ndoi\n:\n10.1103\/PhysRevA.47.2506\n.\nPMID\n \n9909217\n.\n^\nZurek, Wojciech H.\n(2003). \"Decoherence, einselection, and the quantum origins of the classical\".\nReviews of Modern Physics\n.\n75\n(3): 715.\narXiv\n:\nquant-ph\/0105127\n.\nBibcode\n:\n2003RvMP...75..715Z\n.\ndoi\n:\n10.1103\/revmodphys.75.715\n.\nS2CID\n \n14759237\n.\n^\nWojciech H. Zurek\n, \"Decoherence and the transition from quantum to classical\",\nPhysics Today\n, 44, pp. 36–44 (1991)\n^\nHome, D.; Whitaker, M. A. B. (1992). \"Ensemble Interpretations of Quantum Mechanics: A Modern Perspective\".\nPhysics Reports\n.\n210\n(4):\n223–\n317.\nBibcode\n:\n1992PhR...210..223H\n.\ndoi\n:\n10.1016\/0370-1573(92)90088-H\n.\n^\nRovelli, Carlo\n(1996). \"Relational Quantum Mechanics\".\nInternational Journal of Theoretical Physics\n.\n35\n(8):\n1637–\n1678.\narXiv\n:\nquant-ph\/9609002\n.\nBibcode\n:\n1996IJTP...35.1637R\n.\ndoi\n:\n10.1007\/BF02302261\n.\nS2CID\n \n16325959\n.\n^\nCramer, John G. (July 1986).\n\"The transactional interpretation of quantum mechanics\"\n.\nReviews of Modern Physics\n.\n58\n(3):\n647–\n685.\nBibcode\n:\n1986RvMP...58..647C\n.\ndoi\n:\n10.1103\/RevModPhys.58.647\n.\n^\nOkon, Elias; Sudarsky, Daniel (February 1, 2014). \"Benefits of Objective Collapse Models for Cosmology and Quantum Gravity\".\nFoundations of Physics\n.\n44\n(2):\n114–\n143.\narXiv\n:\n1309.1730\n.\nBibcode\n:\n2014FoPh...44..114O\n.\ndoi\n:\n10.1007\/s10701-014-9772-6\n.\nISSN\n \n1572-9516\n.\nS2CID\n \n67831520\n.\n^\nKhazali, Mohammadsadegh; Lau, Hon Wai; Humeniuk, Adam; Simon, Christoph (August 11, 2016). \"Large energy superpositions via Rydberg dressing\".\nPhysical Review A\n.\n94\n(2) 023408.\narXiv\n:\n1509.01303\n.\nBibcode\n:\n2016PhRvA..94b3408K\n.\ndoi\n:\n10.1103\/physreva.94.023408\n.\nISSN\n \n2469-9926\n.\nS2CID\n \n118364289\n.\n^\n\"What is the world's biggest Schrodinger cat?\"\n.\nstackexchange.com\n.\nArchived\nfrom the original on January 8, 2012.\n^\n\"NIST Researchers Create 'Quantum Cats' Made of Light\"\n.\nNIST\n. August 31, 2010. Archived from\nthe original\non May 7, 2017.\n^\nSychev, Demid V.; Ulanov, Alexander E.; Pushkina, Anastasia A.; Richards, Matthew W.; Fedorov, Ilya A.; Lvovsky, Alexander I. (June 2017).\n\"Enlargement of optical Schrödinger's cat states\"\n.\nNature Photonics\n.\n11\n(6):\n379–\n382.\narXiv\n:\n1609.08425\n.\nBibcode\n:\n2017NaPho..11..379S\n.\ndoi\n:\n10.1038\/nphoton.2017.57\n.\nISSN\n \n1749-4885\n.\n^\nMonroe, C.; Meekhof, D. M.; King, B. E.; Wineland, D. J. (May 24, 1996). \"A \"Schrödinger's cat\" Superposition State of an Atom\".\nScience\n.\n272\n(5265):\n1131–\n1136.\nBibcode\n:\n1996Sci...272.1131M\n.\ndoi\n:\n10.1126\/science.272.5265.1131\n.\nPMID\n \n8662445\n.\nS2CID\n \n2311821\n.\n^\n\"Physics World:\nSchrödinger's cat comes into view\n\"\n. July 5, 2000.\n^\nCastelvecchi, Davide.\n\"Macro-Weirdness: \"Quantum Microphone\" Puts Naked-Eye Object in 2 Places at Once\"\n.\nScientific American\n. Archived from\nthe original\non March 19, 2012.\n^\nRomero-Isart, O.; Juan, M. L.; Quidant, R.; Cirac, J. I. (2010). \"Toward Quantum Superposition of Living Organisms\".\nNew Journal of Physics\n.\n12\n(3) 033015.\narXiv\n:\n0909.1469\n.\nBibcode\n:\n2010NJPh...12c3015R\n.\ndoi\n:\n10.1088\/1367-2630\/12\/3\/033015\n.\nS2CID\n \n59151724\n.\n^\n\"Could 'Schrödinger's bacterium' be placed in a quantum superposition?\"\n.\nphysicsworld.com\n.\nArchived\nfrom the original on July 30, 2016.\n^\nNajjar, Dana (November 7, 2019).\n\"Physicists Can Finally Peek at Schrödinger's Cat Without Killing It Forever\"\n.\nLive Science\n. Retrieved\nNovember 7,\n2019\n.\n^\nPatekar, Kartik; Hofmann, Holger F. (2019).\n\"The role of system–meter entanglement in controlling the resolution and decoherence of quantum measurements\"\n.\nNew Journal of Physics\n.\n21\n(10): 103006.\narXiv\n:\n1905.09978\n.\nBibcode\n:\n2019NJPh...21j3006P\n.\ndoi\n:\n10.1088\/1367-2630\/ab4451\n.\n^\nCrease, Robert P. (May 27, 2024).\n\"Ursula Le Guin: the pioneering author we should thank for popularizing Schrödinger's cat\"\n.\nPhysics World\n. Retrieved\nOctober 27,\n2024\n.\n^\nSam Stall (May 1, 2007).\n100 Cats Who Changed Civilization\n. Quirk Books. p. 34.\nISBN\n \n978-1-59474-163-0\n.\n^\na\nb\nCrease, Robert P. (2012).\n\"The cat that never dies\"\n.\nPhysics World\n.\n25\n(4):\n18–\n19.\nBibcode\n:\n2012PhyW...25d..18C\n.\ndoi\n:\n10.1088\/2058-7058\/25\/04\/27\n.\n^\nRyan, Marie-Laure (2011).\n\"Narrative\/Science Entanglements: On the Thousand and One Literary Lives of Schrödinger's Cat\"\n.\nNarrative\n.\n19\n(2):\n171–\n186.\nISSN\n \n1063-3685\n.\nJSTOR\n \n41289295\n.\n^\nKravitz, Bennett (2013).\n\"Thoughts on the Anti-Detective in Paul Auster's \"New York Trilogy\", Adam Ross's \"Mister Peanut\", and Martha Grimes' \"The Old Wine Shades\"\n\"\n.\nStudies in Popular Culture\n.\n36\n(1):\n45–\n61.\nISSN\n \n0888-5753\n.\nJSTOR\n \n23610151\n.\n^\nBranzburg, Judith V. (October 31, 2000).\n\"Dead cats and live bodies\"\n.\nThe Lesbian Review of Books\n.\n7\n(1): 3.\n^\n\"SFE: Wilson, Robert Anton\"\n.\nsf-encyclopedia.com\n. Retrieved\nDecember 3,\n2022\n.\n^\n\"SFE: Thought Experiment\"\n.\nsf-encyclopedia.com\n. Retrieved\nDecember 3,\n2022\n.\n^\nGoldberg, Matt (April 17, 2020).\n\"A Serious Man Ending Explained: The Crucible of American Judaism\"\n.\nCollider\n. Retrieved\nDecember 3,\n2022\n.\n^\nOrr, Christopher (September 25, 2014).\n\"30 Years of Coens: A Serious Man\"\n.\nThe Atlantic\n. Archived from\nthe original\non December 3, 2022\n. Retrieved\nDecember 3,\n2022\n.\n^\nEbert, Roger\n(March 4, 2013).\n\"The Coen Brothers and Serious Quantum Theory\"\n.\nChicago Sun Times\n. Archived from\nthe original\non October 29, 2020.\n^\nCollis, Clark (June 20, 2014).\n\"Coherence\"\n.\nEntertainment Weekly\n. Archived from\nthe original\non December 3, 2022\n. Retrieved\nDecember 3,\n2022\n.\n^\nLandsman, Peggy (April 1, 2022).\n\"\n\"Schrodinger's Cat\"\n\"\n.\nScientific American\n. Archived from\nthe original\non May 29, 2022\n. Retrieved\nFebruary 22,\n2023\n.\n^\nRobbins, Hollis.\n\"\n\"His Paws Upon The Dish\"\n\"\n.\nPer Contra Journal\n. Per Contra\n. Retrieved\nFebruary 22,\n2023\n.\n^\nEhren, Christine (November 18, 2001).\n\"World Premiere Schrodinger's Girlfriend Closes Nov. 18 at San Fran's Magic\"\n.\nSchrodingers Girlfriend\n. Playbill Review. Archived from\nthe original\non May 17, 2010\n. Retrieved\nJanuary 6,\n2015\n.\n^\nHurwitt, Robert (November 5, 2001).\n\"\n'Girlfriend' runs out of inspiration \/ Ideas bog down physics comedy\"\n.\nSFGate Review\n. Archived from\nthe original\non November 26, 2015\n. Retrieved\nDecember 5,\n2015\n.\n^\nMohan, Geoffrey (August 12, 2013).\n\"Google doodle honors physicist Erwin Schrodinger and his cat\"\n.\nBaltimore Sun\n. Archived from\nthe original\non December 2, 2022\n. Retrieved\nDecember 2,\n2022\n.\n^\nFarrer, Gordon (January 6, 2006).\n\"Sum thing to do with maths genius\"\n.\nThe Age\n. Melbourne. Archived from\nthe original\non January 15, 2008\n. Retrieved\nAugust 28,\n2007\n.\n^\nSingh, Simon\n(October 2014).\n\"Theories of quantum levity\"\n.\nPhysics World\n.\n27\n(10): 80.\nBibcode\n:\n2014PhyW...27j..80S\n.\ndoi\n:\n10.1088\/2058-7058\/27\/10\/41\n.\nISSN\n \n0953-8585\n.\n^\n\"The Famous Schrodinger's Cat Thought Experiment Gets Brought to Life in an Off-Kilter Animation\"\n.\nOpen Culture\n. March 24, 2017. Archived from\nthe original\non December 2, 2022\n. Retrieved\nDecember 2,\n2022\n.\n^\n\"NIGHTMARE シュレーディンガーナイフ 歌詞 – 歌詞探索【歌詞リリ】\"\n.\nLyrical Nonsense\n. Archived from\nthe original\non May 28, 2023\n. Retrieved\nMay 28,\n2023\n.\nFurther reading\nEinstein, Albert\n;\nPodolsky, Boris\n;\nRosen, Nathan\n(May 15, 1935).\n\"Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?\"\n.\nPhysical Review\n.\n47\n(10):\n777–\n780.\nBibcode\n:\n1935PhRv...47..777E\n.\ndoi\n:\n10.1103\/PhysRev.47.777\n.\nLeggett, Tony (August 2000).\n\"New Life for Schrödinger's Cat\"\n(PDF)\n. Physics World. pp. \n23–\n24\n. Retrieved\nFebruary 28,\n2020\n.\nAn article on experiments with \"cat state\" superpositions in superconducting rings, in which the electrons go around the ring in two directions simultaneously.\nTrimmer, John D. (1980). \"The Present Situation in Quantum Mechanics: A Translation of Schrödinger's \"Cat Paradox\" Paper\".\nProceedings of the American Philosophical Society\n.\n124\n(5):\n323–\n338.\nJSTOR\n \n986572\n.\n(\nregistration required\n)\nYam, Phillip (October 9, 2012).\n\"Bringing Schrödinger's Cat to Life\"\n.\nScientific American\n. Retrieved\nFebruary 28,\n2020\n.\nA description of investigations of quantum \"cat states\" and wave function collapse by\nSerge Haroche\nand\nDavid J. Wineland\n, for which they won the 2012\nNobel Prize in Physics\n.\nViolaris, M. (2023).\nA Physics Lab Inside Your Head: Quantum Thought Experiments as an Educational Tool\n. 2023 IEEE International Conference on Quantum Computing and Engineering (QCE). Bellevue, WA, USA. pp. \n58–\n67.\narXiv\n:\n2312.07840\n.\ndoi\n:\n10.1109\/QCE57702.2023.20325\n.\nReduction of the Schrödinger's cat to a simple\nquantum circuit\n.\nExternal links\nA spoken word version\nof this article (created from a revision of the article dated 2013-08-12).\nSchrödinger's Cat\nfrom the Information Philosopher.\nSchrödinger's Cat - Sixty Symbols\n- a video published by  the\nUniversity of Nottingham\n.\nSchrödinger's Cat\n- a podcast produced by Sift.","attrs_markdown":"[Jump to content](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#bodyContent)\n\nMain menu\n\nMain menu\n\nmove to sidebar\n\nhide\n\nNavigation\n\n- [Main page](https:\/\/en.wikipedia.org\/wiki\/Main_Page \"Visit the main page [z]\")\n- [Contents](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Contents \"Guides to browsing Wikipedia\")\n- [Current events](https:\/\/en.wikipedia.org\/wiki\/Portal:Current_events \"Articles related to current events\")\n- [Random article](https:\/\/en.wikipedia.org\/wiki\/Special:Random \"Visit a randomly selected article [x]\")\n- [About Wikipedia](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:About \"Learn about Wikipedia and how it works\")\n- [Contact us](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Contact_us \"How to contact Wikipedia\")\n\nContribute\n\n- [Help](https:\/\/en.wikipedia.org\/wiki\/Help:Contents \"Guidance on how to use and edit Wikipedia\")\n- [Learn to edit](https:\/\/en.wikipedia.org\/wiki\/Help:Introduction \"Learn how to edit Wikipedia\")\n- [Community portal](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Community_portal \"The hub for editors\")\n- [Recent changes](https:\/\/en.wikipedia.org\/wiki\/Special:RecentChanges \"A list of recent changes to Wikipedia [r]\")\n- [Upload file](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:File_upload_wizard \"Add images or other media for use on Wikipedia\")\n- [Special pages](https:\/\/en.wikipedia.org\/wiki\/Special:SpecialPages \"A list of all special pages [q]\")\n\n[![](https:\/\/en.wikipedia.org\/static\/images\/icons\/enwiki-25.svg) ![Wikipedia](https:\/\/en.wikipedia.org\/static\/images\/mobile\/copyright\/wikipedia-wordmark-en-25.svg) ![The Free Encyclopedia](https:\/\/en.wikipedia.org\/static\/images\/mobile\/copyright\/wikipedia-tagline-en-25.svg)](https:\/\/en.wikipedia.org\/wiki\/Main_Page)\n\n[Search](https:\/\/en.wikipedia.org\/wiki\/Special:Search \"Search Wikipedia [f]\")\n\nAppearance\n\n- [Donate](https:\/\/donate.wikimedia.org\/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en)\n- [Create account](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:CreateAccount&returnto=Schr%C3%B6dinger%27s+cat \"You are encouraged to create an account and log in; however, it is not mandatory\")\n- [Log in](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:UserLogin&returnto=Schr%C3%B6dinger%27s+cat \"You're encouraged to log in; however, it's not mandatory. [o]\")\n\nPersonal tools\n\n- [Donate](https:\/\/donate.wikimedia.org\/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en)\n- [Create account](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:CreateAccount&returnto=Schr%C3%B6dinger%27s+cat \"You are encouraged to create an account and log in; however, it is not mandatory\")\n- [Log in](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:UserLogin&returnto=Schr%C3%B6dinger%27s+cat \"You're encouraged to log in; however, it's not mandatory. [o]\")\n\n## Contents\nmove to sidebar\n\nhide\n\n- [(Top)](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat)\n- [1 Origin and motivation](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Origin_and_motivation)\n- [2 Thought experiment](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Thought_experiment)\n- [3 Analysis](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Analysis)\n- [4 Interpretations](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Interpretations)\n  Toggle Interpretations subsection\n  - [4\\.1 Copenhagen interpretation](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Copenhagen_interpretation)\n  - [4\\.2 Role of consciousness](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Role_of_consciousness)\n  - [4\\.3 Bohr's interpretation](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Bohr's_interpretation)\n  - [4\\.4 Many-worlds interpretation](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Many-worlds_interpretation)\n  - [4\\.5 Ensemble interpretation](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Ensemble_interpretation)\n  - [4\\.6 Relational interpretation](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Relational_interpretation)\n  - [4\\.7 Transactional interpretation](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Transactional_interpretation)\n  - [4\\.8 Objective collapse theories](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Objective_collapse_theories)\n- [5 Applications and tests](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Applications_and_tests)\n- [6 In popular culture](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#In_popular_culture)\n- [7 See also](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#See_also)\n- [8 References](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#References)\n- [9 Further reading](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#Further_reading)\n- [10 External links](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#External_links)\n\nToggle the table of contents\n\n# Schrödinger's cat\n79 languages\n\n- [Afrikaans](https:\/\/af.wikipedia.org\/wiki\/Schr%C3%B6dinger_se_kat \"Schrödinger se kat – Afrikaans\")\n- [العربية](https:\/\/ar.wikipedia.org\/wiki\/%D9%82%D8%B7%D8%A9_%D8%B4%D8%B1%D9%88%D8%AF%D9%86%D8%BA%D8%B1 \"قطة شرودنغر – Arabic\")\n- [Asturianu](https:\/\/ast.wikipedia.org\/wiki\/Gatu_de_Schr%C3%B6dinger \"Gatu de Schrödinger – Asturian\")\n- [Azərbaycanca](https:\/\/az.wikipedia.org\/wiki\/%C5%9Eredingerin_pi%C5%9Fiyi \"Şredingerin pişiyi – Azerbaijani\")\n- [تۆرکجه](https:\/\/azb.wikipedia.org\/wiki\/%D8%B4%D8%B1%D9%88%D8%AF%DB%8C%D9%86%D9%82%D8%B1%DB%8C%D9%86_%D9%BE%DB%8C%D8%B4%DB%8C%DA%AF%DB%8C \"شرودینقرین پیشیگی – South Azerbaijani\")\n- [Беларуская](https:\/\/be.wikipedia.org\/wiki\/%D0%9A%D0%BE%D1%82_%D0%A8%D1%80%D0%BE%D0%B4%D0%B7%D1%96%D0%BD%D0%B3%D0%B5%D1%80%D0%B0 \"Кот Шродзінгера – Belarusian\")\n- [Български](https:\/\/bg.wikipedia.org\/wiki\/%D0%9A%D0%BE%D1%82%D0%BA%D0%B0_%D0%BD%D0%B0_%D0%A8%D1%80%D1%8C%D0%BE%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80 \"Котка на Шрьодингер – Bulgarian\")\n- [বাংলা](https:\/\/bn.wikipedia.org\/wiki\/%E0%A6%B6%E0%A7%8D%E0%A6%B0%E0%A7%8B%E0%A6%A1%E0%A6%BF%E0%A6%99%E0%A7%8D%E0%A6%97%E0%A6%BE%E0%A6%B0%E0%A7%87%E0%A6%B0_%E0%A6%AC%E0%A6%BF%E0%A6%A1%E0%A6%BC%E0%A6%BE%E0%A6%B2 \"শ্রোডিঙ্গারের বিড়াল – Bangla\")\n- [বিষ্ণুপ্রিয়া মণিপুরী](https:\/\/bpy.wikipedia.org\/wiki\/%E0%A6%B6%E0%A7%8D%E0%A6%B0%E0%A7%8B%E0%A6%A1%E0%A6%BF%E0%A6%99%E0%A7%8D%E0%A6%97%E0%A6%BE%E0%A6%B0%E0%A6%B0_%E0%A6%AE%E0%A7%87%E0%A6%95%E0%A7%81%E0%A6%B0 \"শ্রোডিঙ্গারর মেকুর – Bishnupriya\")\n- [Català](https:\/\/ca.wikipedia.org\/wiki\/Gat_de_Schr%C3%B6dinger \"Gat de Schrödinger – Catalan\")\n- [Čeština](https:\/\/cs.wikipedia.org\/wiki\/Schr%C3%B6dingerova_ko%C4%8Dka \"Schrödingerova kočka – Czech\")\n- [Чӑвашла](https:\/\/cv.wikipedia.org\/wiki\/%D0%A8%D1%80%D1%91%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80_%D0%BA%D1%83%D1%88%D0%B0%D0%BA%C4%95 \"Шрёдингер кушакĕ – Chuvash\")\n- [Dansk](https:\/\/da.wikipedia.org\/wiki\/Schr%C3%B6dingers_kat \"Schrödingers kat – Danish\")\n- [Deutsch](https:\/\/de.wikipedia.org\/wiki\/Schr%C3%B6dingers_Katze \"Schrödingers Katze – German\")\n- [Zazaki](https:\/\/diq.wikipedia.org\/wiki\/P%C4%B1s%C4%B1nga_Schr%C3%B6dingeri \"Pısınga Schrödingeri – Dimli\")\n- [Ελληνικά](https:\/\/el.wikipedia.org\/wiki\/%CE%93%CE%AC%CF%84%CE%B1_%CF%84%CE%BF%CF%85_%CE%A3%CF%81%CE%AD%CE%BD%CF%84%CE%B9%CE%BD%CE%B3%CE%BA%CE%B5%CF%81 \"Γάτα του Σρέντινγκερ – Greek\")\n- [Esperanto](https:\/\/eo.wikipedia.org\/wiki\/Kato_de_Schr%C3%B6dinger \"Kato de Schrödinger – Esperanto\")\n- [Español](https:\/\/es.wikipedia.org\/wiki\/Gato_de_Schr%C3%B6dinger \"Gato de Schrödinger – Spanish\")\n- [Eesti](https:\/\/et.wikipedia.org\/wiki\/Schr%C3%B6dingeri_kass \"Schrödingeri kass – Estonian\")\n- [Euskara](https:\/\/eu.wikipedia.org\/wiki\/Schr%C3%B6dingerren_katua \"Schrödingerren katua – Basque\")\n- [فارسی](https:\/\/fa.wikipedia.org\/wiki\/%DA%AF%D8%B1%D8%A8%D9%87_%D8%B4%D8%B1%D9%88%D8%AF%DB%8C%D9%86%DA%AF%D8%B1 \"گربه شرودینگر – Persian\")\n- [Suomi](https:\/\/fi.wikipedia.org\/wiki\/Schr%C3%B6dingerin_kissa \"Schrödingerin kissa – Finnish\")\n- [Français](https:\/\/fr.wikipedia.org\/wiki\/Chat_de_Schr%C3%B6dinger \"Chat de Schrödinger – French\")\n- [Gaeilge](https:\/\/ga.wikipedia.org\/wiki\/Cat_Schr%C3%B6dinger \"Cat Schrödinger – Irish\")\n- [Galego](https:\/\/gl.wikipedia.org\/wiki\/Gato_de_Schr%C3%B6dinger \"Gato de Schrödinger – Galician\")\n- [עברית](https:\/\/he.wikipedia.org\/wiki\/%D7%94%D7%97%D7%AA%D7%95%D7%9C_%D7%A9%D7%9C_%D7%A9%D7%A8%D7%93%D7%99%D7%A0%D7%92%D7%A8 \"החתול של שרדינגר – Hebrew\")\n- [हिन्दी](https:\/\/hi.wikipedia.org\/wiki\/%E0%A4%B6%E0%A5%8D%E0%A4%B0%E0%A5%8B%E0%A4%A1%E0%A4%BF%E0%A4%82%E0%A4%97%E0%A4%B0_%E0%A4%95%E0%A5%80_%E0%A4%AC%E0%A4%BF%E0%A4%B2%E0%A5%8D%E0%A4%B2%E0%A5%80 \"श्रोडिंगर की बिल्ली – Hindi\")\n- [Hrvatski](https:\/\/hr.wikipedia.org\/wiki\/Schr%C3%B6dingerova_ma%C4%8Dka \"Schrödingerova mačka – Croatian\")\n- [Magyar](https:\/\/hu.wikipedia.org\/wiki\/Schr%C3%B6dinger_macsk%C3%A1ja \"Schrödinger macskája – Hungarian\")\n- [Հայերեն](https:\/\/hy.wikipedia.org\/wiki\/%D5%87%D6%80%D5%B5%D5%B8%D5%A4%D5%AB%D5%B6%D5%A3%D5%A5%D6%80%D5%AB_%D5%AF%D5%A1%D5%BF%D5%B8%D6%82 \"Շրյոդինգերի կատու – Armenian\")\n- [Interlingua](https:\/\/ia.wikipedia.org\/wiki\/Catto_de_Schr%C3%B6dinger \"Catto de Schrödinger – Interlingua\")\n- [Bahasa Indonesia](https:\/\/id.wikipedia.org\/wiki\/Kucing_Schr%C3%B6dinger \"Kucing Schrödinger – Indonesian\")\n- [Italiano](https:\/\/it.wikipedia.org\/wiki\/Paradosso_del_gatto_di_Schr%C3%B6dinger \"Paradosso del gatto di Schrödinger – Italian\")\n- [日本語](https:\/\/ja.wikipedia.org\/wiki\/%E3%82%B7%E3%83%A5%E3%83%AC%E3%83%BC%E3%83%87%E3%82%A3%E3%83%B3%E3%82%AC%E3%83%BC%E3%81%AE%E7%8C%AB \"シュレーディンガーの猫 – Japanese\")\n- [ქართული](https:\/\/ka.wikipedia.org\/wiki\/%E1%83%A8%E1%83%A0%E1%83%94%E1%83%93%E1%83%98%E1%83%9C%E1%83%92%E1%83%94%E1%83%A0%E1%83%98%E1%83%A1_%E1%83%99%E1%83%90%E1%83%A2%E1%83%90 \"შრედინგერის კატა – Georgian\")\n- [한국어](https:\/\/ko.wikipedia.org\/wiki\/%EC%8A%88%EB%A2%B0%EB%94%A9%EA%B1%B0%EC%9D%98_%EA%B3%A0%EC%96%91%EC%9D%B4 \"슈뢰딩거의 고양이 – Korean\")\n- [Kurdî](https:\/\/ku.wikipedia.org\/wiki\/Pis%C3%AEka_Schrodinger \"Pisîka Schrodinger – Kurdish\")\n- [Lietuvių](https:\/\/lt.wikipedia.org\/wiki\/%C5%A0riodingerio_kat%C4%97 \"Šriodingerio katė – Lithuanian\")\n- [Latviešu](https:\/\/lv.wikipedia.org\/wiki\/%C5%A0r%C4%93dingera_ka%C4%B7is \"Šrēdingera kaķis – Latvian\")\n- [Македонски](https:\/\/mk.wikipedia.org\/wiki\/%D0%A8%D1%80%D0%B5%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80%D0%BE%D0%B2%D0%B0_%D0%BC%D0%B0%D1%87%D0%BA%D0%B0 \"Шредингерова мачка – Macedonian\")\n- [മലയാളം](https:\/\/ml.wikipedia.org\/wiki\/%E0%B4%B7%E0%B5%8D%E0%B4%B0%E0%B5%8B%E0%B4%A1%E0%B4%BF%E0%B4%99%E0%B5%8D%E0%B4%99%E0%B4%B1%E0%B5%81%E0%B4%9F%E0%B5%86_%E0%B4%AA%E0%B5%82%E0%B4%9A%E0%B5%8D%E0%B4%9A \"ഷ്രോഡിങ്ങറുടെ പൂച്ച – Malayalam\")\n- [मराठी](https:\/\/mr.wikipedia.org\/wiki\/%E0%A4%B6%E0%A5%8D%E0%A4%B0%E0%A5%8D%E0%A4%AF%E0%A5%89%E0%A4%A1%E0%A4%BF%E0%A4%82%E0%A4%97%E0%A4%B0%E0%A4%9A%E0%A5%87_%E0%A4%AE%E0%A4%BE%E0%A4%82%E0%A4%9C%E0%A4%B0 \"श्र्यॉडिंगरचे मांजर – Marathi\")\n- [Bahasa Melayu](https:\/\/ms.wikipedia.org\/wiki\/Kucing_Schr%C3%B6dinger \"Kucing Schrödinger – Malay\")\n- [مازِرونی](https:\/\/mzn.wikipedia.org\/wiki\/%D8%B4%D8%B1%D9%88%D8%AF%DB%8C%D9%86%DA%AF%D8%B1_%D8%A8%D8%A7%D9%85%D8%B4%DB%8C \"شرودینگر بامشی – Mazanderani\")\n- [Nederlands](https:\/\/nl.wikipedia.org\/wiki\/Schr%C3%B6dingers_kat \"Schrödingers kat – Dutch\")\n- [Norsk nynorsk](https:\/\/nn.wikipedia.org\/wiki\/Schr%C3%B6dingers_katt \"Schrödingers katt – Norwegian Nynorsk\")\n- [Norsk bokmål](https:\/\/no.wikipedia.org\/wiki\/Schr%C3%B6dingers_katt \"Schrödingers katt – Norwegian Bokmål\")\n- [Occitan](https:\/\/oc.wikipedia.org\/wiki\/Gat_de_Schr%C3%B6dinger \"Gat de Schrödinger – Occitan\")\n- [ଓଡ଼ିଆ](https:\/\/or.wikipedia.org\/wiki\/%E0%AC%B8%E0%AD%8D%E0%AC%95%E0%AD%8D%E0%AC%B0%E0%AD%8B%E0%AC%A1%E0%AC%BF%E0%AC%99%E0%AD%8D%E0%AC%97%E0%AC%B0%E0%AC%99%E0%AD%8D%E0%AC%95_%E0%AC%AC%E0%AC%BF%E0%AC%B0%E0%AC%BE%E0%AC%A1%E0%AC%BC%E0%AC%BF \"ସ୍କ୍ରୋଡିଙ୍ଗରଙ୍କ ବିରାଡ଼ି – Odia\")\n- [ਪੰਜਾਬੀ](https:\/\/pa.wikipedia.org\/wiki\/%E0%A8%B8%E0%A8%BC%E0%A8%B0%E0%A9%8B%E0%A8%A1%E0%A8%BF%E0%A9%B0%E0%A8%97%E0%A8%B0_%E0%A8%A6%E0%A9%80_%E0%A8%AC%E0%A8%BF%E0%A9%B1%E0%A8%B2%E0%A9%80 \"ਸ਼ਰੋਡਿੰਗਰ ਦੀ ਬਿੱਲੀ – Punjabi\")\n- [Polski](https:\/\/pl.wikipedia.org\/wiki\/Kot_Schr%C3%B6dingera \"Kot Schrödingera – Polish\")\n- [پنجابی](https:\/\/pnb.wikipedia.org\/wiki\/%D8%B4%D8%B1%D9%88%DA%88%D9%86%DA%AF%D8%B1_%D8%AF%DB%8C_%D8%A8%D9%84%DB%8C \"شروڈنگر دی بلی – Western Punjabi\")\n- [Português](https:\/\/pt.wikipedia.org\/wiki\/Gato_de_Schr%C3%B6dinger \"Gato de Schrödinger – Portuguese\")\n- [Română](https:\/\/ro.wikipedia.org\/wiki\/Pisica_lui_Schr%C3%B6dinger \"Pisica lui Schrödinger – Romanian\")\n- [Русский](https:\/\/ru.wikipedia.org\/wiki\/%D0%9A%D0%BE%D1%82_%D0%A8%D1%80%D1%91%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80%D0%B0 \"Кот Шрёдингера – Russian\")\n- [Саха тыла](https:\/\/sah.wikipedia.org\/wiki\/%D0%A8%D1%80%D1%91%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80_%D0%BA%D1%83%D0%BE%D1%81%D0%BA%D0%B0%D1%82%D0%B0 \"Шрёдингер куоската – Yakut\")\n- [Sicilianu](https:\/\/scn.wikipedia.org\/wiki\/Jattu_di_Schr%C3%B6dinger \"Jattu di Schrödinger – Sicilian\")\n- [Srpskohrvatski \/ српскохрватски](https:\/\/sh.wikipedia.org\/wiki\/Schr%C3%B6dingerova_ma%C4%8Dka \"Schrödingerova mačka – Serbo-Croatian\")\n- [Simple English](https:\/\/simple.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat \"Schrödinger's cat – Simple English\")\n- [Slovenščina](https:\/\/sl.wikipedia.org\/wiki\/Schr%C3%B6dingerjeva_ma%C4%8Dka \"Schrödingerjeva mačka – Slovenian\")\n- [Српски \/ srpski](https:\/\/sr.wikipedia.org\/wiki\/%D0%A8%D1%80%D0%B5%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80%D0%BE%D0%B2%D0%B0_%D0%BC%D0%B0%D1%87%D0%BA%D0%B0 \"Шредингерова мачка – Serbian\")\n- [Svenska](https:\/\/sv.wikipedia.org\/wiki\/Schr%C3%B6dingers_katt \"Schrödingers katt – Swedish\")\n- [Ślůnski](https:\/\/szl.wikipedia.org\/wiki\/Kot_%C3%B4d_Schr%C3%B6dingera \"Kot ôd Schrödingera – Silesian\")\n- [தமிழ்](https:\/\/ta.wikipedia.org\/wiki\/%E0%AE%9A%E0%AF%81%E0%AE%B0%E0%AF%8B%E0%AE%9F%E0%AE%BF%E0%AE%99%E0%AF%8D%E0%AE%95%E0%AE%B0%E0%AE%BF%E0%AE%A9%E0%AF%8D_%E0%AE%AA%E0%AF%82%E0%AE%A9%E0%AF%88 \"சுரோடிங்கரின் பூனை – Tamil\")\n- [తెలుగు](https:\/\/te.wikipedia.org\/wiki\/%E0%B0%B7%E0%B1%8D%E0%B0%B0%E0%B1%8B%E0%B0%A1%E0%B0%BF%E0%B0%82%E0%B0%97%E0%B0%B0%E0%B1%8D_%E0%B0%AA%E0%B0%BF%E0%B0%B2%E0%B1%8D%E0%B0%B2%E0%B0%BF \"ష్రోడింగర్ పిల్లి – Telugu\")\n- [ไทย](https:\/\/th.wikipedia.org\/wiki\/%E0%B9%81%E0%B8%A1%E0%B8%A7%E0%B8%82%E0%B8%AD%E0%B8%87%E0%B8%8A%E0%B9%80%E0%B8%A3%E0%B8%AD%E0%B8%94%E0%B8%B4%E0%B8%87%E0%B9%80%E0%B8%87%E0%B8%AD%E0%B8%A3%E0%B9%8C \"แมวของชเรอดิงเงอร์ – Thai\")\n- [Türkmençe](https:\/\/tk.wikipedia.org\/wiki\/%C5%9Er%C3%BDodingeri%C5%88_pi%C5%9Figi \"Şrýodingeriň pişigi – Turkmen\")\n- [Tagalog](https:\/\/tl.wikipedia.org\/wiki\/Pusa_ni_Schr%C3%B6dinger \"Pusa ni Schrödinger – Tagalog\")\n- [Türkçe](https:\/\/tr.wikipedia.org\/wiki\/Schr%C3%B6dinger%27in_kedisi \"Schrödinger'in kedisi – Turkish\")\n- [Татарча \/ tatarça](https:\/\/tt.wikipedia.org\/wiki\/%D0%A8%D1%80%D3%A9%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80_%D0%BC%D3%99%D1%87%D0%B5%D1%81%D0%B5 \"Шрөдингер мәчесе – Tatar\")\n- [Українська](https:\/\/uk.wikipedia.org\/wiki\/%D0%9A%D1%96%D1%82_%D0%A8%D1%80%D0%B5%D0%B4%D1%96%D0%BD%D0%B3%D0%B5%D1%80%D0%B0 \"Кіт Шредінгера – Ukrainian\")\n- [Oʻzbekcha \/ ўзбекча](https:\/\/uz.wikipedia.org\/wiki\/Schr%C3%B6dinger_mushugi \"Schrödinger mushugi – Uzbek\")\n- [Vèneto](https:\/\/vec.wikipedia.org\/wiki\/Paradoso_del_gato_de_Schr%C3%B6dinger \"Paradoso del gato de Schrödinger – Venetian\")\n- [Tiếng Việt](https:\/\/vi.wikipedia.org\/wiki\/Con_m%C3%A8o_c%E1%BB%A7a_Schr%C3%B6dinger \"Con mèo của Schrödinger – Vietnamese\")\n- [Winaray](https:\/\/war.wikipedia.org\/wiki\/Misay_nga_Schr%C3%B6ndinger \"Misay nga Schröndinger – Waray\")\n- [吴语](https:\/\/wuu.wikipedia.org\/wiki\/%E8%96%9B%E5%AE%9A%E8%B0%94%E7%8C%AB \"薛定谔猫 – Wu\")\n- [文言](https:\/\/zh-classical.wikipedia.org\/wiki\/%E8%96%9B%E5%AE%9A%E8%AB%A4%E4%B9%8B%E8%B2%93 \"薛定諤之貓 – Literary Chinese\")\n- [粵語](https:\/\/zh-yue.wikipedia.org\/wiki\/%E8%96%9B%E5%AE%9A%E8%AB%A4%E8%B2%93 \"薛定諤貓 – Cantonese\")\n- [中文](https:\/\/zh.wikipedia.org\/wiki\/%E8%96%9B%E5%AE%9A%E8%B0%94%E7%8C%AB \"薛定谔猫 – Chinese\")\n\n[Edit links](https:\/\/www.wikidata.org\/wiki\/Special:EntityPage\/Q8588#sitelinks-wikipedia \"Edit interlanguage links\")\n\n- [Article](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat \"View the content page [c]\")\n- [Talk](https:\/\/en.wikipedia.org\/wiki\/Talk:Schr%C3%B6dinger%27s_cat \"Discuss improvements to the content page [t]\")\n\nEnglish\n\n- [Read](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat)\n- [View source](https:\/\/en.wikipedia.org\/w\/index.php?title=Schr%C3%B6dinger%27s_cat&action=edit \"This page is protected.\n  You can view its source [e]\")\n- [View history](https:\/\/en.wikipedia.org\/w\/index.php?title=Schr%C3%B6dinger%27s_cat&action=history \"Past revisions of this page [h]\")\n\nTools\n\nTools\n\nmove to sidebar\n\nhide\n\nActions\n\n- [Read](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat)\n- [View 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sidebar\n\nhide\n\n[![Page semi-protected](https:\/\/upload.wikimedia.org\/wikipedia\/en\/thumb\/1\/1b\/Semi-protection-shackle.svg\/20px-Semi-protection-shackle.svg.png)](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Protection_policy#semi \"This article is semi-protected until November 15, 2028 at 06:24 UTC.\")\n\nFrom Wikipedia, the free encyclopedia\n\nThought experiment in quantum mechanics\n\nFor other uses, see [Schrödinger's cat (disambiguation)](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat_\\(disambiguation\\) \"Schrödinger's cat (disambiguation)\").\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/9\/91\/Schrodingers_cat.svg\/500px-Schrodingers_cat.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Schrodingers_cat.svg)\n\nSchrödinger's cat: a cat, a flask of poison, and a [radioactive](https:\/\/en.wikipedia.org\/wiki\/Radioactive \"Radioactive\") source connected to a [Geiger counter](https:\/\/en.wikipedia.org\/wiki\/Geiger_counter \"Geiger counter\") are placed in a sealed box. As illustrated, the quantum description uses a superposition of an alive cat and one that has died.\n\nIn [quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Quantum_mechanics \"Quantum mechanics\"), **Schrödinger's cat** is a [thought experiment](https:\/\/en.wikipedia.org\/wiki\/Thought_experiment \"Thought experiment\") concerning [quantum superposition](https:\/\/en.wikipedia.org\/wiki\/Quantum_superposition \"Quantum superposition\"). In the thought experiment, a hypothetical [cat](https:\/\/en.wikipedia.org\/wiki\/Cat \"Cat\") in a closed box may be considered to be simultaneously both alive and dead while it is unobserved, as a result of its fate being linked to a random [subatomic](https:\/\/en.wikipedia.org\/wiki\/Subatomic_particle \"Subatomic particle\") event that may or may not occur. This experiment, viewed this way, is described as a [paradox](https:\/\/en.wikipedia.org\/wiki\/Paradox \"Paradox\"). This thought experiment was devised by physicist [Erwin Schrödinger](https:\/\/en.wikipedia.org\/wiki\/Erwin_Schr%C3%B6dinger \"Erwin Schrödinger\") in 1935,[\\[1\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1) in a discussion with [Albert Einstein](https:\/\/en.wikipedia.org\/wiki\/Albert_Einstein \"Albert Einstein\"),[\\[2\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Fine-2) to illustrate what Schrödinger saw as the problems of [Niels Bohr](https:\/\/en.wikipedia.org\/wiki\/Niels_Bohr \"Niels Bohr\") and [Werner Heisenberg](https:\/\/en.wikipedia.org\/wiki\/Werner_Heisenberg \"Werner Heisenberg\")'s philosophical views on quantum mechanics.\n\nIn Schrödinger's original formulation, a cat, a flask of poison, and a [radioactive](https:\/\/en.wikipedia.org\/wiki\/Radioactive \"Radioactive\") source are placed in a sealed box. If an internal radiation monitor such as a [Geiger counter](https:\/\/en.wikipedia.org\/wiki\/Geiger_counter \"Geiger counter\") detects radioactivity (a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. If no decaying atom triggers the monitor, the cat remains alive. Mathematically, the [wave function](https:\/\/en.wikipedia.org\/wiki\/Wave_function \"Wave function\") that describes the contents of the box is a combination, or [quantum superposition](https:\/\/en.wikipedia.org\/wiki\/Quantum_superposition \"Quantum superposition\"), of these two possibilities. Yet, when one looks in the box, one sees the cat *either* alive *or* dead, not both alive *and* dead. This poses the question of when exactly quantum superposition ends and reality resolves into one possibility or the other.\n\nAlthough originally a critique of Bohr and Heisenberg, Schrödinger's seemingly paradoxical thought experiment became part of the foundation of quantum mechanics. It is often featured in theoretical discussions of the [interpretations of quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Interpretations_of_quantum_mechanics \"Interpretations of quantum mechanics\"), particularly in situations involving the [measurement problem](https:\/\/en.wikipedia.org\/wiki\/Measurement_problem \"Measurement problem\"). As a result, Schrödinger's cat has had enduring [appeal in popular culture](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat_in_popular_culture \"Schrödinger's cat in popular culture\"). The experiment is not intended to be actually performed on a cat, but rather as an easily understandable illustration of the behavior of atoms. Experiments at the atomic scale have been carried out, showing that very small objects may exist as superpositions, but superposing an object as large as a cat would pose considerable technical difficulties.[\\[3\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-3)\n\nFundamentally, the Schrödinger's cat experiment asks how long quantum superpositions last and when (or whether) they collapse. Different [interpretations of the mathematics of quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Interpretations_of_quantum_mechanics \"Interpretations of quantum mechanics\") have been proposed that give different explanations for this process.\n\n## Origin and motivation\nUnsolved problem in physics\n\nHow does the quantum description of reality, which includes elements such as the superposition of states and wavefunction collapse or quantum decoherence, give rise to the reality we perceive? Another way of stating this question regards the measurement problem: What constitutes a \"measurement\" that apparently causes the wave function to collapse into a definite state?\n\n[More unsolved problems in physics](https:\/\/en.wikipedia.org\/wiki\/List_of_unsolved_problems_in_physics \"List of unsolved problems in physics\")\n\nSchrödinger intended his thought experiment as a discussion of the [EPR article](https:\/\/en.wikipedia.org\/wiki\/Einstein%E2%80%93Podolsky%E2%80%93Rosen_paradox \"Einstein–Podolsky–Rosen paradox\")—named after its authors [Einstein](https:\/\/en.wikipedia.org\/wiki\/Albert_Einstein \"Albert Einstein\"), [Podolsky](https:\/\/en.wikipedia.org\/wiki\/Boris_Podolsky \"Boris Podolsky\"), and [Rosen](https:\/\/en.wikipedia.org\/wiki\/Nathan_Rosen \"Nathan Rosen\")—in 1935.[\\[4\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-4)[\\[5\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5) The EPR article highlighted the counterintuitive nature of [quantum superpositions](https:\/\/en.wikipedia.org\/wiki\/Quantum_superposition \"Quantum superposition\"), in which a quantum system for two particles does not separate[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 150  even when the particles are detected far from their last point of contact. The EPR paper concludes with a claim that this lack of separability meant that quantum mechanics as a theory of reality was incomplete.\n\nSchrödinger and Einstein exchanged letters about Einstein's EPR article, in the course of which Einstein pointed out that the state of an [unstable](https:\/\/en.wikipedia.org\/wiki\/Unstable \"Unstable\") keg of [gunpowder](https:\/\/en.wikipedia.org\/wiki\/Gunpowder \"Gunpowder\") will, after a while, contain a superposition of both exploded and unexploded states.[\\[5\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5) To further illustrate, Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a closed steel chamber, wherein the cat's life or death depended on the state of a [radioactive](https:\/\/en.wikipedia.org\/wiki\/Radioactive \"Radioactive\") atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the position taken by Bohr and Heisenberg would be that *the cat remains both alive and dead* until the state has been observed. Schrödinger did not wish to promote the idea of dead-and-live cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics,[\\[1\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1) thus employing *[reductio ad absurdum](https:\/\/en.wikipedia.org\/wiki\/Reductio_ad_absurdum \"Reductio ad absurdum\")*.\n\nSince Schrödinger's time, various [interpretations of the mathematics of quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Interpretations_of_quantum_mechanics \"Interpretations of quantum mechanics\") have been advanced by physicists, some of which regard the \"alive and dead\" cat superposition as quite real, while others do not.[\\[7\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Polkinghorne-7)[\\[8\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Tetlow-8) Intended as a critique of ideas prevalent in 1935, the Schrödinger's cat thought experiment remains a [touchstone](https:\/\/en.wikipedia.org\/wiki\/Touchstone_\\(metaphor\\) \"Touchstone (metaphor)\") for modern interpretations of quantum mechanics and can be used to illustrate and compare their strengths and weaknesses.[\\[9\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-9)\\[*[better source needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Verifiability#Questionable_sources \"Wikipedia:Verifiability\")*\\]\n\n## Thought experiment\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/5e\/Schroedinger_cat.jpg\/330px-Schroedinger_cat.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Schroedinger_cat.jpg)\n\nA life-size cat figure in the garden of Huttenstrasse 9, Zurich, where [Erwin Schrödinger](https:\/\/en.wikipedia.org\/wiki\/Erwin_Schr%C3%B6dinger \"Erwin Schrödinger\") lived from 1921 to 1926. Depending on the light conditions, the figure appears to be either a live cat or a dead one.\n\nSchrödinger wrote:[\\[1\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1)[\\[10\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-10)\n\n> One can contrive even completely burlesque \\[farcical\\] cases. A cat is put in a steel chamber along with the following infernal device (which must be secured against direct interference by the cat): in a [Geiger counter](https:\/\/en.wikipedia.org\/wiki\/Geiger_counter \"Geiger counter\"), there is a tiny amount of radioactive substance, so tiny that in the course of an hour one of the atoms will perhaps decay, but also, with equal probability, that none of them will; if it does happen, the counter tube will discharge and through a relay release a hammer that will shatter a small flask of [hydrocyanic acid](https:\/\/en.wikipedia.org\/wiki\/Hydrocyanic_acid \"Hydrocyanic acid\"). If one has left this entire system to itself for an hour, one would tell oneself that the cat is still alive if no atom has [decayed](https:\/\/en.wikipedia.org\/wiki\/Radioactive_decay \"Radioactive decay\") in the meantime. Even a single atomic decay would have poisoned it. The [psi-function](https:\/\/en.wikipedia.org\/wiki\/Wave_function \"Wave function\") of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or spread out in equal parts.\n> \n> It is typical of these cases that an indeterminacy originally restricted to the atomic domain turns into a sensually observable \\[macroscopic\\] indeterminacy, which can then be resolved by direct observation. This prevents us from so naïvely accepting a \"blurred model\" as representative of reality. Per se, it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks.\n\nSchrödinger developed his famous [thought experiment](https:\/\/en.wikipedia.org\/wiki\/Thought_experiment \"Thought experiment\") in correspondence with Einstein. He suggested this 'quite ridiculous case' to illustrate his conclusion that the wave function cannot represent reality.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 153  The wave function description of the complete cat system implies that the reality of the cat mixes the living and dead cat.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 154  Einstein was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote:[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 157\n\n> You are the only contemporary physicist, besides [Laue](https:\/\/en.wikipedia.org\/wiki\/Max_von_Laue \"Max von Laue\"), who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gun powder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation.[\\[11\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-11)\n\nNote that the charge of gunpowder is not mentioned in Schrödinger's setup, which uses a Geiger counter as an amplifier and hydrocyanic poison instead of gunpowder. The gunpowder had been mentioned in Einstein's original suggestion to Schrödinger 15 years before, and Einstein carried it forward to the present discussion.[\\[5\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5)\n\n## Analysis\nIn modern terms Schrödinger's hypothetical cat experiment describes the [measurement problem](https:\/\/en.wikipedia.org\/wiki\/Measurement_problem \"Measurement problem\"): quantum theory describes the cat system as a combination of two possible outcomes but only one outcome is ever observed.[\\[12\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-PeresCat-12): 57 [\\[13\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-SchlosshauerDecoherenceReview-13): 1269  The experiment poses the question, \"*when* does a quantum system stop existing as a superposition of states and become one or the other?\" (More technically, when does the actual quantum state stop being a non-trivial [linear combination](https:\/\/en.wikipedia.org\/wiki\/Linear_combination \"Linear combination\") of states, each of which resembles different classical states, and instead begin to have a unique classical description?) Standard microscopic quantum mechanics describes multiple possible outcomes of experiments but only one outcome is observed. The thought experiment illustrates this apparent paradox. Our intuition says that the cat cannot be in more than one state simultaneously—yet the quantum mechanical description of the thought experiment requires such a condition.\n\n## Interpretations\nSince Schrödinger's time, other interpretations of quantum mechanics have been proposed that give different answers to the questions posed by Schrödinger's cat of how long superpositions last and when (or *whether*) they collapse.\n\n### Copenhagen interpretation\nMain article: [Copenhagen interpretation](https:\/\/en.wikipedia.org\/wiki\/Copenhagen_interpretation \"Copenhagen interpretation\")\n\nA commonly held interpretation of quantum mechanics is the Copenhagen interpretation.[\\[14\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Wimmel1992-14) In the Copenhagen interpretation, a measurement results in only one state of a superposition. This thought experiment makes apparent the fact that this interpretation simply provides no explanation for the state of the cat while the box is closed. The wavefunction description of the system consists of a superposition of the states \"decayed nucleus\/dead cat\" and \"undecayed nucleus\/living cat\". Only when the box is opened and observed can we make a statement about the cat.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 157\n\n### Role of consciousness\nMain article: [Consciousness causes collapse](https:\/\/en.wikipedia.org\/wiki\/Consciousness_causes_collapse \"Consciousness causes collapse\")\n\nIn 1932, [John von Neumann](https:\/\/en.wikipedia.org\/wiki\/John_von_Neumann \"John von Neumann\") described in his book *[Mathematical Foundations of Quantum Mechanics](https:\/\/en.wikipedia.org\/wiki\/Mathematical_Foundations_of_Quantum_Mechanics \"Mathematical Foundations of Quantum Mechanics\")* a pattern where the radioactive source is observed by a device, which itself is observed by another device and so on. It makes no difference in the predictions of quantum theory where along this chain of causal effects the superposition collapses.[\\[15\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Tales_of_the_Quantum-15) This potentially infinite chain could be broken if the last device is replaced by a conscious observer. This solved the problem because it was claimed that an individual's consciousness cannot be multiple.[\\[16\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-16) Eugene Wigner asserted that an observer is necessary for a collapse to one or the other (e.g., either a live cat or a dead cat) of the terms on the right-hand side of a [wave function](https:\/\/en.wikipedia.org\/wiki\/Wave_function \"Wave function\"). Wigner discussed the interpretation in a thought experiment known as [Wigner's friend](https:\/\/en.wikipedia.org\/wiki\/Wigner%27s_friend \"Wigner's friend\").[\\[17\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Surfing_the_Quantum_World-17) Wigner supposed that a friend opened the box and observed the cat without telling anyone. From Wigner's conscious perspective, the friend is now part of the wave function and has seen a live cat and seen a dead cat. To a third person's conscious perspective, Wigner himself becomes part of the wave function once Wigner learns the outcome from the friend. This could be extended indefinitely.[\\[17\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Surfing_the_Quantum_World-17)\n\nA resolution of the paradox is that the triggering of the Geiger counter counts as a measurement of the state of the radioactive substance. Because a measurement has already occurred deciding the state of the cat, the subsequent observation by a human records only what has already occurred.[\\[18\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-18) Analysis of an actual experiment by [Roger Carpenter](https:\/\/en.wikipedia.org\/wiki\/Roger_Carpenter \"Roger Carpenter\") and A. J. Anderson found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before any human knows of the result.[\\[19\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Carpenter2006-19) The apparatus indicates one of two colors depending on the outcome. The human observer sees which color is indicated, but does not consciously know which outcome the color represents. A second human, the one who set up the apparatus, is told of the color and becomes conscious of the outcome, and the box is opened to check if the outcome matches.[\\[15\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Tales_of_the_Quantum-15) However, it is disputed whether merely observing the color counts as a conscious observation of the outcome.[\\[20\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Okon2006-20)\n\n### Bohr's interpretation\nAnalysis of the work of [Niels Bohr](https:\/\/en.wikipedia.org\/wiki\/Niels_Bohr \"Niels Bohr\"), one of the main scientists associated with the Copenhagen interpretation, suggests he viewed the state of the cat before the box is opened as indeterminate. The superposition itself had no physical meaning to Bohr: Schrödinger's cat would be either dead or alive long before the box is opened but the cat and box form an inseparable combination.[\\[21\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Faye2008-21) Bohr saw no role for a human observer.[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-22): 35  Bohr emphasized the classical nature of measurement results. An \"irreversible\" or effectively irreversible process imparts the classical behavior of \"observation\" or \"measurement\".[\\[23\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-23)[\\[24\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-24)[\\[25\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-25)\n\n### Many-worlds interpretation\nMain article: [Many-worlds interpretation](https:\/\/en.wikipedia.org\/wiki\/Many-worlds_interpretation \"Many-worlds interpretation\")\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/c\/c8\/Schroedingers_cat_film.svg\/250px-Schroedingers_cat_film.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Schroedingers_cat_film.svg)\n\nThe quantum-mechanical \"Schrödinger's cat\" paradox according to the many-worlds interpretation. In this interpretation, every event is a branch point. The cat is both alive and dead—regardless of whether the box is opened—but the \"alive\" and \"dead\" cats are in different branches of the universe that are equally real but cannot interact with each other.\n\nIn 1957, [Hugh Everett](https:\/\/en.wikipedia.org\/wiki\/Hugh_Everett \"Hugh Everett\") formulated the many-worlds interpretation of quantum mechanics, which does not single out observation as a special process. In the many-worlds interpretation, both alive and dead states of the cat persist after the box is opened, but are [decoherent](https:\/\/en.wikipedia.org\/wiki\/Quantum_decoherence \"Quantum decoherence\") from each other. In other words, when the box is opened, the observer and the possibly-dead cat split into an observer looking at a box with a dead cat and an observer looking at a box with a live cat. But since the dead and alive states are decoherent, there is no communication or interaction between them.\n\nWhen opening the box, the observer becomes entangled with the cat, so \"observer states\" corresponding to the cat's being alive and dead are formed; each observer state is [entangled](https:\/\/en.wikipedia.org\/wiki\/Quantum_entanglement \"Quantum entanglement\"), or linked, with the cat so that the observation of the cat's state and the cat's state correspond with each other. Quantum decoherence ensures that the different outcomes have no interaction with each other. Decoherence is generally considered to prevent simultaneous observation of multiple states.[\\[26\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-zurek03-26)[\\[27\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-zurek91-27)\n\nA variant of the Schrödinger's cat experiment, known as the [quantum suicide](https:\/\/en.wikipedia.org\/wiki\/Quantum_suicide_and_immortality \"Quantum suicide and immortality\") machine, has been proposed by cosmologist [Max Tegmark](https:\/\/en.wikipedia.org\/wiki\/Max_Tegmark \"Max Tegmark\"). It examines the Schrödinger's cat experiment from the point of view of the cat, and argues that by using this approach, one may be able to distinguish between the Copenhagen interpretation and many-worlds.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\n### Ensemble interpretation\nIn [Ensemble interpretations](https:\/\/en.wikipedia.org\/wiki\/Ensemble_interpretation \"Ensemble interpretation\"), superpositions are sub-ensembles of a larger statistical ensemble. The state vector would not apply to individual cat experiments, but only to the statistics of many similarly prepared cat experiments. Proponents of these interpretations argue that this makes the Schrödinger's cat paradox a trivial matter, or a non-issue. When the physicist opens the box, they simply discover which subensemble that specific cat belonged to.[\\[28\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-28)\n\n### Relational interpretation\nMain article: [Relational quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Relational_quantum_mechanics \"Relational quantum mechanics\")\n\nThe [relational interpretation](https:\/\/en.wikipedia.org\/wiki\/Relational_quantum_mechanics \"Relational quantum mechanics\") makes no fundamental distinction between the human experimenter, the cat, and the apparatus or between animate and inanimate systems; all are quantum systems governed by the same rules of wavefunction [evolution](https:\/\/en.wikipedia.org\/wiki\/Time_evolution \"Time evolution\"), and all may be considered \"observers\". But the relational interpretation allows that different observers can give different accounts of the same series of events, depending on the information they have about the system.[\\[29\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-29)\\[*[non-primary source needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources \"Wikipedia:No original research\")*\\] The cat can be considered an observer of the apparatus; meanwhile, the experimenter can be considered another observer of the system in the box (the cat plus the apparatus). Before the box is opened, the cat, by nature of its being alive or dead, has information about the state of the apparatus (the atom has either decayed or not decayed); but the experimenter does not have information about the state of the box contents. In this way, the two observers simultaneously have different accounts of the situation: To the cat, the wavefunction of the apparatus has appeared to \"collapse\"; to the experimenter, the contents of the box appear to be in superposition. Not until the box is opened, and both observers have the same information about what happened, do both system states appear to \"collapse\" into the same definite result, a cat that is either alive or dead.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\n### Transactional interpretation\nIn the [transactional interpretation](https:\/\/en.wikipedia.org\/wiki\/Transactional_interpretation \"Transactional interpretation\") the apparatus emits an advanced wave backward in time, which combined with the wave that the source emits forward in time, forms a standing wave. The waves are seen as physically real, and the apparatus is considered an \"observer\". In the transactional interpretation, the collapse of the wavefunction is \"atemporal\" and occurs along the whole transaction between the source and the apparatus. The cat is never in superposition. Rather the cat is only in one state at any particular time, regardless of when the human experimenter looks in the box. The transactional interpretation resolves this quantum paradox.[\\[30\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-30)\\[*[non-primary source needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources \"Wikipedia:No original research\")*\\]\n\n### Objective collapse theories\nAccording to [objective collapse theories](https:\/\/en.wikipedia.org\/wiki\/Objective-collapse_theory \"Objective-collapse theory\"), superpositions are destroyed spontaneously (irrespective of external observation) when some objective physical threshold (of time, mass, temperature, [irreversibility](https:\/\/en.wikipedia.org\/wiki\/Irreversibility \"Irreversibility\"), etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is opened. This could loosely be phrased as \"the cat observes itself\" or \"the environment observes the cat\".\n\nObjective collapse theories require a modification of standard quantum mechanics to allow superpositions to be destroyed by the process of time evolution.[\\[31\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-31) These theories could ideally be tested by creating mesoscopic superposition states in the experiment. For instance, energy cat states have been proposed as a precise detector of the quantum gravity related energy decoherence models.[\\[32\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-32)\n\n## Applications and tests\nSchrödinger's cat quantum superposition of states and effect of the environment through decoherence\n\nThe experiment as described is a purely theoretical one, and the machine proposed is not known to have been constructed. However, successful experiments involving similar principles, e.g. superpositions of [relatively large](https:\/\/en.wikipedia.org\/wiki\/Mesoscopic \"Mesoscopic\") (by the standards of quantum physics) objects have been performed.[\\[33\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-33)\\[*[better source needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Verifiability#Questionable_sources \"Wikipedia:Verifiability\")*\\] These experiments do not show that a cat-sized object can be superposed, but the known upper limit on \"[cat states](https:\/\/en.wikipedia.org\/wiki\/Cat_state \"Cat state\")\" has been pushed upwards by them. In many cases the state is short-lived, even when cooled to near [absolute zero](https:\/\/en.wikipedia.org\/wiki\/Absolute_zero \"Absolute zero\").\n\n- A \"cat state\" has been achieved with photons.[\\[34\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-34)[\\[35\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-35)\n- A beryllium ion has been trapped in a superposed state.[\\[36\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-36)\n- An experiment involving a [superconducting quantum interference device](https:\/\/en.wikipedia.org\/wiki\/Superconducting_quantum_interference_device \"Superconducting quantum interference device\") (\"SQUID\") has been linked to the theme of the thought experiment: \"The superposition state does not correspond to a billion electrons flowing one way and a billion others flowing the other way. Superconducting electrons move en masse. All the superconducting electrons in the SQUID flow both ways around the loop at once when they are in the Schrödinger's cat state.\"[\\[37\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-37)\n- A [piezoelectric](https:\/\/en.wikipedia.org\/wiki\/Piezoelectric \"Piezoelectric\") \"tuning fork\" has been constructed, which can be placed into a superposition of vibrating and non vibrating states. The resonator comprises about 10 trillion atoms.[\\[38\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-38)\n- An experiment involving a flu virus has been proposed.[\\[39\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-39)\n- An experiment involving a bacterium and an electromechanical oscillator has been proposed.[\\[40\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-40)\n\nIn [quantum computing](https:\/\/en.wikipedia.org\/wiki\/Quantum_computing \"Quantum computing\") the phrase \"cat state\" sometimes refers to the [GHZ state](https:\/\/en.wikipedia.org\/wiki\/Greenberger%E2%80%93Horne%E2%80%93Zeilinger_state \"Greenberger–Horne–Zeilinger state\"), wherein several qubits are in an equal superposition of all being 0 and all being 1; e.g.,\n\n\\|\n\nψ\n\n⟩\n\n\\=\n\n1\n\n2\n\n(\n\n\\|\n\n00\n\n…\n\n0\n\n⟩\n\n\\+\n\n\\|\n\n11\n\n…\n\n1\n\n⟩\n\n)\n\n.\n\n{\\\\displaystyle \\|\\\\psi \\\\rangle ={\\\\frac {1}{\\\\sqrt {2}}}{\\\\bigg (}\\|00\\\\ldots 0\\\\rangle +\\|11\\\\ldots 1\\\\rangle {\\\\bigg )}.}\n\n![{\\\\displaystyle \\|\\\\psi \\\\rangle ={\\\\frac {1}{\\\\sqrt {2}}}{\\\\bigg (}\\|00\\\\ldots 0\\\\rangle +\\|11\\\\ldots 1\\\\rangle {\\\\bigg )}.}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/26aac0fa72a1f19180f6d2914259cadd8f07be74)\n\nAccording to at least one proposal, it may be possible to determine the state of the cat *before* observing it.[\\[41\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-LS-20191107-41)[\\[42\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-NJP-20191001-42)\n\n## In popular culture\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/e\/ed\/SchroCat.jpg\/250px-SchroCat.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:SchroCat.jpg)\n\nThis drawing by [F. Gwynplaine MacIntyre](https:\/\/en.wikipedia.org\/wiki\/F._Gwynplaine_MacIntyre \"F. Gwynplaine MacIntyre\"), originally published in *[Analog](https:\/\/en.wikipedia.org\/wiki\/Analog_Science_Fiction_and_Fact \"Analog Science Fiction and Fact\")* magazine, illustrates MacIntyre's science-fiction story \"Schrödinger's Cat-Sitter\". The cat is depicted simultaneously in front of and behind the [impossible trident](https:\/\/en.wikipedia.org\/wiki\/Impossible_trident \"Impossible trident\") in an [optical illusion](https:\/\/en.wikipedia.org\/wiki\/Optical_illusion \"Optical illusion\").\n\nAccording to historian of science [Robert P. Crease](https:\/\/en.wikipedia.org\/wiki\/Robert_P._Crease \"Robert P. Crease\"), Schrödinger's thought experiment did not become widely known until the 1970s. In 1972 [Ursula K. Le Guin](https:\/\/en.wikipedia.org\/wiki\/Ursula_K._Le_Guin \"Ursula K. Le Guin\") learned about it while researching quantum mechanics for her novel *[The Dispossessed](https:\/\/en.wikipedia.org\/wiki\/The_Dispossessed \"The Dispossessed\")*; Crease credits her 1974 short story \"Schrödinger's Cat\" with bringing the concept into popular culture.[\\[43\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-43) Other [science-fiction](https:\/\/en.wikipedia.org\/wiki\/Science_fiction \"Science fiction\") writers soon picked it up, often using it in a humorous vein.[\\[44\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-100CCC-44) Works of fiction have employed Schrödinger's thought experiment as plot device and as [metaphor](https:\/\/en.wikipedia.org\/wiki\/Metaphor \"Metaphor\"), in genres from [apocalyptic science fiction](https:\/\/en.wikipedia.org\/wiki\/Apocalyptic_science_fiction \"Apocalyptic science fiction\") to young-adult drama, making the cat more prominent in popular culture than in physics itself.[\\[45\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Crease-45)[\\[46\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-46)[\\[47\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-47)[\\[48\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-48)\n\nSchrödinger's cat has been a motive in many science fiction works, and used as a title of a number of them, including [Greg Bear](https:\/\/en.wikipedia.org\/wiki\/Greg_Bear \"Greg Bear\")'s \"Schrödinger's Plague\" (*[Analog](https:\/\/en.wikipedia.org\/wiki\/Analog_Science_Fiction_and_Fact \"Analog Science Fiction and Fact\")*, 29 March 1982), [George Alec Effinger](https:\/\/en.wikipedia.org\/wiki\/George_Alec_Effinger \"George Alec Effinger\")'s \"[Schrödinger's Kitten](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_Kitten \"Schrödinger's Kitten\")\" (*[Omni](https:\/\/en.wikipedia.org\/wiki\/Omni_\\(magazine\\) \"Omni (magazine)\")*, September 1988), [F. Gwynplaine MacIntyre](https:\/\/en.wikipedia.org\/wiki\/F._Gwynplaine_MacIntyre \"F. Gwynplaine MacIntyre\")'s \"Schrödinger's Cat-Sitter\" (*Analog*, July\/August 2001), [Rudy Rucker](https:\/\/en.wikipedia.org\/wiki\/Rudy_Rucker \"Rudy Rucker\")'s \"Schrödinger's Cat\" (*Analog*, 30 March 1981), and [Robert Anton Wilson](https:\/\/en.wikipedia.org\/wiki\/Robert_Anton_Wilson \"Robert Anton Wilson\")'s *[Schrödinger's Cat Trilogy](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_Cat_Trilogy \"Schrödinger's Cat Trilogy\")* (1988), illustrating various [interpretations of quantum physics](https:\/\/en.wikipedia.org\/wiki\/Interpretations_of_quantum_mechanics \"Interpretations of quantum mechanics\").[\\[49\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-49)[\\[50\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-50) In addition to novels and short stories, Schrödinger's cat has appeared in film,[\\[51\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-51)[\\[52\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-52)[\\[53\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-53)[\\[54\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-54) poetry,[\\[55\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-55)[\\[56\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-56) theatre,[\\[57\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger's_Girlfriend-57)[\\[58\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Schrodingers_Girlfriend_SFG-58) live-action television,[\\[59\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-59) cartoons,[\\[60\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-The_Age-60)[\\[61\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-61)[\\[62\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-62) music,[\\[63\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-63) and webcomics.[\\[45\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Crease-45)\n\n## See also\n- [![icon](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/6\/6f\/Stylised_atom_with_three_Bohr_model_orbits_and_stylised_nucleus.svg\/40px-Stylised_atom_with_three_Bohr_model_orbits_and_stylised_nucleus.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Stylised_atom_with_three_Bohr_model_orbits_and_stylised_nucleus.svg)[Physics portal](https:\/\/en.wikipedia.org\/wiki\/Portal:Physics \"Portal:Physics\")\n\n- [Basis function](https:\/\/en.wikipedia.org\/wiki\/Basis_function \"Basis function\")\n- [Cat state](https:\/\/en.wikipedia.org\/wiki\/Cat_state \"Cat state\")\n- [Complementarity (physics)](https:\/\/en.wikipedia.org\/wiki\/Complementarity_\\(physics\\) \"Complementarity (physics)\")\n- [Double-slit experiment](https:\/\/en.wikipedia.org\/wiki\/Double-slit_experiment \"Double-slit experiment\")\n- [Elitzur–Vaidman bomb tester](https:\/\/en.wikipedia.org\/wiki\/Elitzur%E2%80%93Vaidman_bomb_tester \"Elitzur–Vaidman bomb tester\")\n- [Heisenberg cut](https:\/\/en.wikipedia.org\/wiki\/Heisenberg_cut \"Heisenberg cut\")\n- [Modal realism](https:\/\/en.wikipedia.org\/wiki\/Modal_realism \"Modal realism\")\n- [Observer effect (physics)](https:\/\/en.wikipedia.org\/wiki\/Observer_effect_\\(physics\\) \"Observer effect (physics)\")\n- [Ray cat](https:\/\/en.wikipedia.org\/wiki\/Ray_cat \"Ray cat\")\n- [Schroedinbug](https:\/\/en.wikipedia.org\/wiki\/Schroedinbug \"Schroedinbug\")\n## References\n1. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-1) [***c***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-2)\n   [Schrödinger, Erwin](https:\/\/en.wikipedia.org\/wiki\/Erwin_Schr%C3%B6dinger \"Erwin Schrödinger\") (November 1935). \"Die gegenwärtige Situation in der Quantenmechanik (The Present Situation in Quantum Mechanics)\". *[Naturwissenschaften](https:\/\/en.wikipedia.org\/wiki\/Naturwissenschaften \"Naturwissenschaften\")*. **23** (48): 807–812\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1935NW.....23..807S](https:\/\/ui.adsabs.harvard.edu\/abs\/1935NW.....23..807S). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1007\/BF01491891](https:\/\/doi.org\/10.1007%2FBF01491891). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [206795705](https:\/\/api.semanticscholar.org\/CorpusID:206795705). \"Man kann auch ganz burleske Fälle konstruieren. Eine Katze wird in eine Stahlkammer gesperrt, zusammen mit folgender Höllenmaschine (die man gegen den direkten Zugriff der Katze sichern muß): in einem Geigerschen Zählrohr befindet sich eine winzige Menge radioaktiver Substanz, so wenig, daß im Laufe einer Stunde vielleicht eines von den Atomen zerfällt, ebenso wahrscheinlich aber auch keines; geschieht es, so spricht das Zählrohr an und betätigt über ein Relais ein Hämmerchen, das ein Kölbchen mit Blausäure zertrümmert. Hat man dieses ganze System eine Stunde lang sich selbst überlassen, so wird man sich sagen, daß die Katze noch lebt, wenn inzwischen kein Atom zerfallen ist. Der erste Atomzerfall würde sie vergiftet haben. Die Psi-Funktion des ganzen Systems würde das so zum Ausdruck bringen, daß in ihr die lebende und die tote Katze (s.v.v.) \\[sit venia verbo\\] zu gleichen Teilen gemischt oder verschmiert sind. Das Typische an solchen Fällen ist, daß eine ursprünglich auf den Atombereich beschränkte Unbestimmtheit sich in grobsinnliche Unbestimmtheit umsetzt, die sich dann durch direkte Beobachtung entscheiden läßt. Das hindert uns, in so naiver Weise ein \"verwaschenes Modell\" als Abbild der Wirklichkeit gelten zu lassen. An sich enthielte es nichts Unklares oder Widerspruchsvolles. Es ist ein Unterschied zwischen einer verwackelten oder unscharf eingestellten Photographie und einer Aufnahme von Wolken und Nebelschwaden.\"\n2. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Fine_2-0)**\n   [Fine, Arthur](https:\/\/en.wikipedia.org\/wiki\/Arthur_Fine \"Arthur Fine\"). [\"The Einstein-Podolsky-Rosen Argument in Quantum Theory\"](https:\/\/plato.stanford.edu\/entries\/qt-epr\/). *Stanford Encyclopedia of Philosophy*. Retrieved June 11, 2020.\n3. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-3)**\n   [Ball, Philip](https:\/\/en.wikipedia.org\/wiki\/Philip_Ball \"Philip Ball\") (June 25, 2018). [\"Real-Life Schrödinger's Cats Probe the Boundary of the Quantum World\"](https:\/\/web.archive.org\/web\/20250228155932\/https:\/\/www.quantamagazine.org\/real-life-schrodingers-cats-probe-the-boundary-of-the-quantum-world-20180625\/). *Quanta Magazine*. Archived from [the original](https:\/\/www.quantamagazine.org\/real-life-schrodingers-cats-probe-the-boundary-of-the-quantum-world-20180625\/) on February 28, 2025. Retrieved February 24, 2025.\n4. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-4)**\n   Einstein, A.; Podolsky, B.; Rosen, N. (May 15, 1935). \"Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?\". *Physical Review*. **47** (10): 777–780\\. [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/PhysRev.47.777](https:\/\/doi.org\/10.1103%2FPhysRev.47.777). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0031-899X](https:\/\/search.worldcat.org\/issn\/0031-899X).\n5. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-1) [***c***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-2)\n   Fine, Arthur (2017). [\"The Einstein-Podolsky-Rosen Argument in Quantum Theory\"](https:\/\/plato.stanford.edu\/entries\/qt-epr\/). *Stanford Encyclopedia of Philosophy*. Stanford University. Retrieved April 11, 2021.\n6. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-1) [***c***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-2) [***d***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-3) [***e***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-4)\n   Baggott, J. E. (2013). *The quantum story: a history in 40 moments* (Impression: 3 ed.). Oxford: Oxford Univ. Press. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n   \n   [978-0-19-965597-7](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-0-19-965597-7 \"Special:BookSources\/978-0-19-965597-7\")\n   \n   .\n7. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Polkinghorne_7-0)**\n   Polkinghorne, J. C. (1985). [*The Quantum World*](https:\/\/books.google.com\/books?id=lp4JPYnLrtEC&q=%22schrodinger%27s+cat%22+%22alive+dead&pg=PA67). [Princeton University Press](https:\/\/en.wikipedia.org\/wiki\/Princeton_University_Press \"Princeton University Press\"). p. 67. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n   \n   [0-691-02388-3](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/0-691-02388-3 \"Special:BookSources\/0-691-02388-3\")\n   \n   . [Archived](https:\/\/web.archive.org\/web\/20150519001623\/https:\/\/books.google.com\/books?id=lp4JPYnLrtEC&pg=PA67&dq=%22schrodinger%27s+cat%22+%22alive+dead) from the original on May 19, 2015. Retrieved November 20, 2020.\n8. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Tetlow_8-0)**\n   Tetlow, Philip (2012). [*Understanding Information and Computation: From Einstein to Web Science*](https:\/\/books.google.com\/books?id=Rk7O3EG0Xn4C&q=%22alive+and+dead%22&pg=PA321). Gower Publishing, Ltd. p. 321. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n   \n   [978-1-4094-4040-6](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-4094-4040-6 \"Special:BookSources\/978-1-4094-4040-6\")\n   \n   . [Archived](https:\/\/web.archive.org\/web\/20150519001741\/https:\/\/books.google.com\/books?id=Rk7O3EG0Xn4C&pg=PA321&dq=%22alive+and+dead%22) from the original on May 19, 2015.\n9. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-9)**\n   Lazarou, Dimitris (2007). \"Interpretation of quantum theory - An overview\". [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[0712\\.3466](https:\/\/arxiv.org\/abs\/0712.3466) \\[[quant-ph](https:\/\/arxiv.org\/archive\/quant-ph)\\].\n10. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-10)**\n    Trimmer, John D. (1980). \"The Present Situation in Quantum Mechanics: A Translation of Schrödinger's \"Cat Paradox\" Paper\". *Proceedings of the American Philosophical Society*. **124** (5): 323–338\\. [JSTOR](https:\/\/en.wikipedia.org\/wiki\/JSTOR_\\(identifier\\) \"JSTOR (identifier)\") [986572](https:\/\/www.jstor.org\/stable\/986572).\n    \n    The English translation here is based on the German original, not on the inaccurate version in this source's translation of the entire article: [Schrödinger: \"The Present Situation in Quantum Mechanics.\" 5. Are the Variables Really Blurred?](http:\/\/web.archive.org\/web\/20161020061333\/https:\/\/www.tuhh.de\/rzt\/rzt\/it\/QM\/cat.html)\n11. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-11)**\n    Maxwell, Nicholas (January 1, 1993). \"Induction and Scientific Realism: Einstein versus van Fraassen Part Three: Einstein, Aim-Oriented Empiricism and the Discovery of Special and General Relativity\". *The British Journal for the Philosophy of Science*. **44** (2): 275–305\\. [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1093\/bjps\/44.2.275](https:\/\/doi.org\/10.1093%2Fbjps%2F44.2.275). [JSTOR](https:\/\/en.wikipedia.org\/wiki\/JSTOR_\\(identifier\\) \"JSTOR (identifier)\") [687649](https:\/\/www.jstor.org\/stable\/687649).\n12. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-PeresCat_12-0)**\n    [Peres, Asher](https:\/\/en.wikipedia.org\/wiki\/Asher_Peres \"Asher Peres\") (January 1988). [\"Schrödinger's immortal cat\"](http:\/\/link.springer.com\/10.1007\/BF01882873). *Foundations of Physics*. **18** (1): 57–76\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1988FoPh...18...57P](https:\/\/ui.adsabs.harvard.edu\/abs\/1988FoPh...18...57P). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1007\/BF01882873](https:\/\/doi.org\/10.1007%2FBF01882873). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0015-9018](https:\/\/search.worldcat.org\/issn\/0015-9018).\n13. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-SchlosshauerDecoherenceReview_13-0)**\n    Schlosshauer, Maximilian (February 23, 2005). [\"Decoherence, the measurement problem, and interpretations of quantum mechanics\"](https:\/\/link.aps.org\/doi\/10.1103\/RevModPhys.76.1267). *Reviews of Modern Physics*. **76** (4): 1267–1305\\. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[quant-ph\/0312059](https:\/\/arxiv.org\/abs\/quant-ph\/0312059). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2004RvMP...76.1267S](https:\/\/ui.adsabs.harvard.edu\/abs\/2004RvMP...76.1267S). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/RevModPhys.76.1267](https:\/\/doi.org\/10.1103%2FRevModPhys.76.1267).\n14. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Wimmel1992_14-0)**\n    Wimmel, Hermann (1992). [*Quantum physics & observed reality: a critical interpretation of quantum mechanics*](https:\/\/books.google.com\/books?id=-4sJ_fgyZJEC&pg=PA2). World Scientific. p. 2. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-981-02-1010-6](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-981-02-1010-6 \"Special:BookSources\/978-981-02-1010-6\")\n    \n    . [Archived](https:\/\/web.archive.org\/web\/20130520185205\/http:\/\/books.google.com\/books?id=-4sJ_fgyZJEC&pg=PA2) from the original on May 20, 2013. Retrieved May 9, 2011.\n15. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Tales_of_the_Quantum_15-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Tales_of_the_Quantum_15-1)\n    Hobson, Art (2017). [*Tales of the Quantum: Understanding Physics' Most Fundamental Theory*](https:\/\/books.google.com\/books?id=mGduDQAAQBAJ). New York, NY: Oxford University Press. pp. 200–202\\. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-0-19-067963-7](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-0-19-067963-7 \"Special:BookSources\/978-0-19-067963-7\")\n    \n    . Retrieved April 8, 2022.\n16. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-16)**\n    [Omnès, Roland](https:\/\/en.wikipedia.org\/wiki\/Roland_Omn%C3%A8s \"Roland Omnès\") (1999). [*Understanding Quantum Mechanics*](https:\/\/books.google.com\/books?id=XET_DwAAQBAJ). Princeton, New Jersey: Princeton University Press. pp. 60–62\\. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [0-691-00435-8](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/0-691-00435-8 \"Special:BookSources\/0-691-00435-8\")\n    \n    . Retrieved April 8, 2022.\n17. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Surfing_the_Quantum_World_17-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Surfing_the_Quantum_World_17-1)\n    Levin, Frank S. (2017). [*Surfing the Quantum World*](https:\/\/books.google.com\/books?id=Y1w-DwAAQBAJ). New York, NY: Oxford University Press. pp. 229–232\\. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-0-19-880827-5](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-0-19-880827-5 \"Special:BookSources\/978-0-19-880827-5\")\n    \n    . Retrieved April 8, 2022.\n18. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-18)**\n    Puri, Ravinder R. (2017). [*Non-Relativistic Quantum Mechanics*](https:\/\/books.google.com\/books?id=qDbSDgAAQBAJ). Cambridge, United Kingdom: Cambridge University Press. p. 146. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-1-107-16436-9](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-107-16436-9 \"Special:BookSources\/978-1-107-16436-9\")\n    \n    . Retrieved April 8, 2022.\n19. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Carpenter2006_19-0)**\n    Carpenter RHS; Anderson AJ (2006). [\"The death of Schrödinger's cat and of consciousness-based wave-function collapse\"](https:\/\/web.archive.org\/web\/20061130173850\/http:\/\/www.ensmp.fr\/aflb\/AFLB-311\/aflb311m387.pdf) (PDF). *[Annales de la Fondation Louis de Broglie](https:\/\/en.wikipedia.org\/wiki\/Annales_de_la_Fondation_Louis_de_Broglie \"Annales de la Fondation Louis de Broglie\")*. **31** (1): 45–52\\. Archived from [the original](http:\/\/www.ensmp.fr\/aflb\/AFLB-311\/aflb311m387.pdf) (PDF) on November 30, 2006. Retrieved September 10, 2010.\n20. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Okon2006_20-0)**\n    Okón E, Sebastián MA (2016). \"How to Back up or Refute Quantum Theories of Consciousness\". *Mind and Matter*. **14** (1): 25–49\\.\n21. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Faye2008_21-0)**\n    [Faye, J](https:\/\/en.wikipedia.org\/wiki\/Jan_Faye \"Jan Faye\") (January 24, 2008). [\"Copenhagen Interpretation of Quantum Mechanics\"](http:\/\/plato.stanford.edu\/entries\/qm-copenhagen\/). *[Stanford Encyclopedia of Philosophy](https:\/\/en.wikipedia.org\/wiki\/Stanford_Encyclopedia_of_Philosophy \"Stanford Encyclopedia of Philosophy\")*. The Metaphysics Research Lab Center for the Study of Language and Information, [Stanford University](https:\/\/en.wikipedia.org\/wiki\/Stanford_University \"Stanford University\"). Retrieved September 19, 2010.\n22. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-22)**\n    [John Bell](https:\/\/en.wikipedia.org\/wiki\/John_Stewart_Bell \"John Stewart Bell\") (1990). \"Against 'measurement'\". *Physics World*. **3** (8): 33–41\\. [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1088\/2058-7058\/3\/8\/26](https:\/\/doi.org\/10.1088%2F2058-7058%2F3%2F8%2F26).\n23. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-23)**\n    [Niels Bohr](https:\/\/en.wikipedia.org\/wiki\/Niels_Bohr \"Niels Bohr\") (1985) \\[May 16, 1947\\]. Jørgen Kalckar (ed.). [*Foundations of Quantum Physics I (1926-1932)*](https:\/\/www.nbarchive.dk\/publications\/bcw\/). Niels Bohr: Collected Works. Vol. 6. pp. 451–454\\.\n24. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-24)**\n    Stig Stenholm (1983). \"To fathom space and time\". In [Pierre Meystre](https:\/\/en.wikipedia.org\/w\/index.php?title=Pierre_Meystre&action=edit&redlink=1 \"Pierre Meystre (page does not exist)\") (ed.). *Quantum Optics, Experimental Gravitation, and Measurement Theory*. Plenum Press. p. 121. \"The role of irreversibility in the theory of measurement has been emphasized by many. Only this way can a permanent record be obtained. The fact that separate pointer positions must be of the asymptotic nature usually associated with irreversibility has been utilized in the measurement theory of Daneri, Loinger and Prosperi (1962). It has been accepted as a formal representation of Bohr's ideas by Rosenfeld (1966).\"\n25. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-25)**\n    Haake, Fritz (April 1, 1993). \"Classical motion of meter variables in the quantum theory of measurement\". *[Physical Review A](https:\/\/en.wikipedia.org\/wiki\/Physical_Review_A \"Physical Review A\")*. **47** (4): 2506–2517\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1993PhRvA..47.2506H](https:\/\/ui.adsabs.harvard.edu\/abs\/1993PhRvA..47.2506H). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/PhysRevA.47.2506](https:\/\/doi.org\/10.1103%2FPhysRevA.47.2506). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [9909217](https:\/\/pubmed.ncbi.nlm.nih.gov\/9909217).\n26. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-zurek03_26-0)**\n    [Zurek, Wojciech H.](https:\/\/en.wikipedia.org\/wiki\/Wojciech_H._Zurek \"Wojciech H. Zurek\") (2003). \"Decoherence, einselection, and the quantum origins of the classical\". *Reviews of Modern Physics*. **75** (3): 715. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[quant-ph\/0105127](https:\/\/arxiv.org\/abs\/quant-ph\/0105127). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2003RvMP...75..715Z](https:\/\/ui.adsabs.harvard.edu\/abs\/2003RvMP...75..715Z). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/revmodphys.75.715](https:\/\/doi.org\/10.1103%2Frevmodphys.75.715). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [14759237](https:\/\/api.semanticscholar.org\/CorpusID:14759237).\n27. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-zurek91_27-0)** [Wojciech H. Zurek](https:\/\/en.wikipedia.org\/wiki\/Wojciech_H._Zurek \"Wojciech H. Zurek\"), \"Decoherence and the transition from quantum to classical\", *Physics Today*, 44, pp. 36–44 (1991)\n28. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-28)**\n    Home, D.; Whitaker, M. A. B. (1992). \"Ensemble Interpretations of Quantum Mechanics: A Modern Perspective\". *Physics Reports*. **210** (4): 223–317\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1992PhR...210..223H](https:\/\/ui.adsabs.harvard.edu\/abs\/1992PhR...210..223H). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1016\/0370-1573(92)90088-H](https:\/\/doi.org\/10.1016%2F0370-1573%2892%2990088-H).\n29. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-29)**\n    [Rovelli, Carlo](https:\/\/en.wikipedia.org\/wiki\/Carlo_Rovelli \"Carlo Rovelli\") (1996). \"Relational Quantum Mechanics\". *International Journal of Theoretical Physics*. **35** (8): 1637–1678\\. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[quant-ph\/9609002](https:\/\/arxiv.org\/abs\/quant-ph\/9609002). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1996IJTP...35.1637R](https:\/\/ui.adsabs.harvard.edu\/abs\/1996IJTP...35.1637R). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1007\/BF02302261](https:\/\/doi.org\/10.1007%2FBF02302261). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [16325959](https:\/\/api.semanticscholar.org\/CorpusID:16325959).\n30. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-30)**\n    Cramer, John G. (July 1986). [\"The transactional interpretation of quantum mechanics\"](https:\/\/www.researchgate.net\/publication\/280926546). *Reviews of Modern Physics*. **58** (3): 647–685\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1986RvMP...58..647C](https:\/\/ui.adsabs.harvard.edu\/abs\/1986RvMP...58..647C). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/RevModPhys.58.647](https:\/\/doi.org\/10.1103%2FRevModPhys.58.647).\n31. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-31)**\n    Okon, Elias; Sudarsky, Daniel (February 1, 2014). \"Benefits of Objective Collapse Models for Cosmology and Quantum Gravity\". *Foundations of Physics*. **44** (2): 114–143\\. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[1309\\.1730](https:\/\/arxiv.org\/abs\/1309.1730). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2014FoPh...44..114O](https:\/\/ui.adsabs.harvard.edu\/abs\/2014FoPh...44..114O). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1007\/s10701-014-9772-6](https:\/\/doi.org\/10.1007%2Fs10701-014-9772-6). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [1572-9516](https:\/\/search.worldcat.org\/issn\/1572-9516). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [67831520](https:\/\/api.semanticscholar.org\/CorpusID:67831520).\n32. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-32)**\n    Khazali, Mohammadsadegh; Lau, Hon Wai; Humeniuk, Adam; Simon, Christoph (August 11, 2016). \"Large energy superpositions via Rydberg dressing\". *Physical Review A*. **94** (2) 023408. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[1509\\.01303](https:\/\/arxiv.org\/abs\/1509.01303). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2016PhRvA..94b3408K](https:\/\/ui.adsabs.harvard.edu\/abs\/2016PhRvA..94b3408K). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/physreva.94.023408](https:\/\/doi.org\/10.1103%2Fphysreva.94.023408). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [2469-9926](https:\/\/search.worldcat.org\/issn\/2469-9926). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [118364289](https:\/\/api.semanticscholar.org\/CorpusID:118364289).\n33. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-33)**\n    [\"What is the world's biggest Schrodinger cat?\"](http:\/\/physics.stackexchange.com\/questions\/3309\/what-is-the-worlds-biggest-schrodinger-cat). *stackexchange.com*. [Archived](https:\/\/web.archive.org\/web\/20120108000629\/http:\/\/physics.stackexchange.com\/questions\/3309\/what-is-the-worlds-biggest-schrodinger-cat) from the original on January 8, 2012.\n34. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-34)**\n    [\"NIST Researchers Create 'Quantum Cats' Made of Light\"](https:\/\/web.archive.org\/web\/20170507224218\/https:\/\/www.nist.gov\/news-events\/news\/2010\/08\/nist-researchers-create-quantum-cats-made-light). *NIST*. August 31, 2010. Archived from [the original](https:\/\/www.nist.gov\/news-events\/news\/2010\/08\/nist-researchers-create-quantum-cats-made-light) on May 7, 2017.\n35. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-35)**\n    Sychev, Demid V.; Ulanov, Alexander E.; Pushkina, Anastasia A.; Richards, Matthew W.; Fedorov, Ilya A.; Lvovsky, Alexander I. (June 2017). [\"Enlargement of optical Schrödinger's cat states\"](https:\/\/www.nature.com\/articles\/nphoton.2017.57). *Nature Photonics*. **11** (6): 379–382\\. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[1609\\.08425](https:\/\/arxiv.org\/abs\/1609.08425). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2017NaPho..11..379S](https:\/\/ui.adsabs.harvard.edu\/abs\/2017NaPho..11..379S). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1038\/nphoton.2017.57](https:\/\/doi.org\/10.1038%2Fnphoton.2017.57). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [1749-4885](https:\/\/search.worldcat.org\/issn\/1749-4885).\n36. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-36)**\n    Monroe, C.; Meekhof, D. M.; King, B. E.; Wineland, D. J. (May 24, 1996). \"A \"Schrödinger's cat\" Superposition State of an Atom\". *Science*. **272** (5265): 1131–1136\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1996Sci...272.1131M](https:\/\/ui.adsabs.harvard.edu\/abs\/1996Sci...272.1131M). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1126\/science.272.5265.1131](https:\/\/doi.org\/10.1126%2Fscience.272.5265.1131). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [8662445](https:\/\/pubmed.ncbi.nlm.nih.gov\/8662445). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [2311821](https:\/\/api.semanticscholar.org\/CorpusID:2311821).\n37. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-37)**\n    [\"Physics World: *Schrödinger's cat comes into view*\"](https:\/\/physicsworld.com\/a\/schrodingers-cat-comes-into-view\/). July 5, 2000.\n38. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-38)**\n    Castelvecchi, Davide. [\"Macro-Weirdness: \"Quantum Microphone\" Puts Naked-Eye Object in 2 Places at Once\"](https:\/\/web.archive.org\/web\/20120319021316\/http:\/\/www.scientificamerican.com\/article.cfm?id=quantum-microphone). *Scientific American*. Archived from [the original](https:\/\/www.scientificamerican.com\/article\/quantum-microphone\/) on March 19, 2012.\n39. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-39)**\n    Romero-Isart, O.; Juan, M. L.; Quidant, R.; Cirac, J. I. (2010). \"Toward Quantum Superposition of Living Organisms\". *New Journal of Physics*. **12** (3) 033015. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[0909\\.1469](https:\/\/arxiv.org\/abs\/0909.1469). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2010NJPh...12c3015R](https:\/\/ui.adsabs.harvard.edu\/abs\/2010NJPh...12c3015R). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1088\/1367-2630\/12\/3\/033015](https:\/\/doi.org\/10.1088%2F1367-2630%2F12%2F3%2F033015). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [59151724](https:\/\/api.semanticscholar.org\/CorpusID:59151724).\n40. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-40)**\n    [\"Could 'Schrödinger's bacterium' be placed in a quantum superposition?\"](http:\/\/physicsworld.com\/cws\/article\/news\/2015\/sep\/21\/could-schrodingers-bacterium-be-placed-in-a-quantum-superposition). *physicsworld.com*. [Archived](https:\/\/web.archive.org\/web\/20160730174613\/http:\/\/physicsworld.com\/cws\/article\/news\/2015\/sep\/21\/could-schrodingers-bacterium-be-placed-in-a-quantum-superposition) from the original on July 30, 2016.\n41. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-LS-20191107_41-0)**\n    Najjar, Dana (November 7, 2019). [\"Physicists Can Finally Peek at Schrödinger's Cat Without Killing It Forever\"](https:\/\/www.livescience.com\/schrodingers-cat-can-be-peeked-at.html). *[Live Science](https:\/\/en.wikipedia.org\/wiki\/Live_Science \"Live Science\")*. Retrieved November 7, 2019.\n42. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-NJP-20191001_42-0)**\n    Patekar, Kartik; Hofmann, Holger F. (2019). [\"The role of system–meter entanglement in controlling the resolution and decoherence of quantum measurements\"](https:\/\/doi.org\/10.1088%2F1367-2630%2Fab4451). *[New Journal of Physics](https:\/\/en.wikipedia.org\/wiki\/New_Journal_of_Physics \"New Journal of Physics\")*. **21** (10): 103006. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[1905\\.09978](https:\/\/arxiv.org\/abs\/1905.09978). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2019NJPh...21j3006P](https:\/\/ui.adsabs.harvard.edu\/abs\/2019NJPh...21j3006P). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1088\/1367-2630\/ab4451](https:\/\/doi.org\/10.1088%2F1367-2630%2Fab4451).\n43. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-43)**\n    Crease, Robert P. (May 27, 2024). [\"Ursula Le Guin: the pioneering author we should thank for popularizing Schrödinger's cat\"](https:\/\/physicsworld.com\/a\/ursula-le-guin-the-pioneering-author-we-should-thank-for-popularizing-schrodingers-cat\/). *Physics World*. Retrieved October 27, 2024.\n44. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-100CCC_44-0)**\n    Sam Stall (May 1, 2007). [*100 Cats Who Changed Civilization*](https:\/\/books.google.com\/books?id=coXIF8WbEKEC). Quirk Books. p. 34. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-1-59474-163-0](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-59474-163-0 \"Special:BookSources\/978-1-59474-163-0\")\n    \n    .\n45. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Crease_45-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Crease_45-1)\n    Crease, Robert P. (2012). [\"The cat that never dies\"](https:\/\/doi.org\/10.1088%2F2058-7058%2F25%2F04%2F27). *Physics World*. **25** (4): 18–19\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2012PhyW...25d..18C](https:\/\/ui.adsabs.harvard.edu\/abs\/2012PhyW...25d..18C). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1088\/2058-7058\/25\/04\/27](https:\/\/doi.org\/10.1088%2F2058-7058%2F25%2F04%2F27).\n46. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-46)**\n    Ryan, Marie-Laure (2011). [\"Narrative\/Science Entanglements: On the Thousand and One Literary Lives of Schrödinger's Cat\"](https:\/\/www.jstor.org\/stable\/41289295). *Narrative*. **19** (2): 171–186\\. [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [1063-3685](https:\/\/search.worldcat.org\/issn\/1063-3685). [JSTOR](https:\/\/en.wikipedia.org\/wiki\/JSTOR_\\(identifier\\) \"JSTOR (identifier)\") [41289295](https:\/\/www.jstor.org\/stable\/41289295).\n47. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-47)**\n    Kravitz, Bennett (2013). [\"Thoughts on the Anti-Detective in Paul Auster's \"New York Trilogy\", Adam Ross's \"Mister Peanut\", and Martha Grimes' \"The Old Wine Shades\"\"](https:\/\/www.jstor.org\/stable\/23610151). *Studies in Popular Culture*. **36** (1): 45–61\\. [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0888-5753](https:\/\/search.worldcat.org\/issn\/0888-5753). [JSTOR](https:\/\/en.wikipedia.org\/wiki\/JSTOR_\\(identifier\\) \"JSTOR (identifier)\") [23610151](https:\/\/www.jstor.org\/stable\/23610151).\n48. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-48)**\n    Branzburg, Judith V. (October 31, 2000). [\"Dead cats and live bodies\"](https:\/\/www.proquest.com\/openview\/a751e740ad411cd002452117c93b4322). *The Lesbian Review of Books*. **7** (1): 3.\n49. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-49)**\n    [\"SFE: Wilson, Robert Anton\"](https:\/\/sf-encyclopedia.com\/entry\/wilson_robert_anton). *sf-encyclopedia.com*. Retrieved December 3, 2022.\n50. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-50)**\n    [\"SFE: Thought Experiment\"](https:\/\/sf-encyclopedia.com\/entry\/thought_experiment). *sf-encyclopedia.com*. Retrieved December 3, 2022.\n51. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-51)**\n    Goldberg, Matt (April 17, 2020). [\"A Serious Man Ending Explained: The Crucible of American Judaism\"](https:\/\/collider.com\/a-serious-man-ending-explained-american-judaism\/). *Collider*. Retrieved December 3, 2022.\n52. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-52)**\n    Orr, Christopher (September 25, 2014). [\"30 Years of Coens: A Serious Man\"](https:\/\/web.archive.org\/web\/20221203220152\/https:\/\/www.theatlantic.com\/entertainment\/archive\/2014\/09\/30-years-of-coens-a-serious-man\/380732\/). *[The Atlantic](https:\/\/en.wikipedia.org\/wiki\/The_Atlantic \"The Atlantic\")*. Archived from [the original](https:\/\/www.theatlantic.com\/entertainment\/archive\/2014\/09\/30-years-of-coens-a-serious-man\/380732\/) on December 3, 2022. Retrieved December 3, 2022.\n53. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-53)**\n    [Ebert, Roger](https:\/\/en.wikipedia.org\/wiki\/Roger_Ebert \"Roger Ebert\") (March 4, 2013). [\"The Coen Brothers and Serious Quantum Theory\"](https:\/\/web.archive.org\/web\/20201029024134\/https:\/\/www.rogerebert.com\/roger-ebert\/the-coen-brothers-and-serious-quantum-theory). *[Chicago Sun Times](https:\/\/en.wikipedia.org\/wiki\/Chicago_Sun_Times \"Chicago Sun Times\")*. Archived from [the original](https:\/\/www.rogerebert.com\/roger-ebert\/the-coen-brothers-and-serious-quantum-theory) on October 29, 2020.\n54. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-54)**\n    Collis, Clark (June 20, 2014). [\"Coherence\"](https:\/\/web.archive.org\/web\/20221203220151\/https:\/\/ew.com\/article\/2014\/06\/20\/coherence\/). *Entertainment Weekly*. Archived from [the original](https:\/\/ew.com\/article\/2014\/06\/20\/coherence\/) on December 3, 2022. Retrieved December 3, 2022.\n55. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-55)**\n    Landsman, Peggy (April 1, 2022). [\"\"Schrodinger's Cat\"\"](https:\/\/web.archive.org\/web\/20220529020959\/https:\/\/www.scientificamerican.com\/article\/poem-schroedingers-cat\/). *Scientific American*. Archived from [the original](https:\/\/www.scientificamerican.com\/article\/poem-schroedingers-cat\/) on May 29, 2022. Retrieved February 22, 2023.\n56. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-56)**\n    Robbins, Hollis. [\"\"His Paws Upon The Dish\"\"](http:\/\/www.percontra.net\/issues\/34\/poetry\/his-paws-upon-the\/). *Per Contra Journal*. Per Contra. Retrieved February 22, 2023.\n57. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger's_Girlfriend_57-0)**\n    Ehren, Christine (November 18, 2001). [\"World Premiere Schrodinger's Girlfriend Closes Nov. 18 at San Fran's Magic\"](https:\/\/web.archive.org\/web\/20100517085507\/http:\/\/www.playbill.com\/news\/article\/63363-World-Premiere-Schrodingers-Girlfriend-Closes-Nov-18-at-San-Frans-Magic). *Schrodingers Girlfriend*. Playbill Review. Archived from [the original](http:\/\/www.playbill.com\/news\/article\/63363-World-Premiere-Schrodingers-Girlfriend-Closes-Nov-18-at-San-Frans-Magic) on May 17, 2010. Retrieved January 6, 2015.\n58. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodingers_Girlfriend_SFG_58-0)**\n    Hurwitt, Robert (November 5, 2001). [\"'Girlfriend' runs out of inspiration \/ Ideas bog down physics comedy\"](https:\/\/web.archive.org\/web\/20151126043542\/http:\/\/www.sfgate.com\/entertainment\/article\/Girlfriend-runs-out-of-inspiration-Ideas-bog-2862061.php). *SFGate Review*. Archived from [the original](http:\/\/www.sfgate.com\/entertainment\/article\/Girlfriend-runs-out-of-inspiration-Ideas-bog-2862061.php) on November 26, 2015. Retrieved December 5, 2015.\n59. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-59)**\n    Mohan, Geoffrey (August 12, 2013). [\"Google doodle honors physicist Erwin Schrodinger and his cat\"](https:\/\/web.archive.org\/web\/20221202232119\/https:\/\/www.baltimoresun.com\/la-sci-sn-schrodinger-cat-20130812-story.html). *Baltimore Sun*. Archived from [the original](https:\/\/www.baltimoresun.com\/la-sci-sn-schrodinger-cat-20130812-story.html) on December 2, 2022. Retrieved December 2, 2022.\n60. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-The_Age_60-0)**\n    Farrer, Gordon (January 6, 2006). [\"Sum thing to do with maths genius\"](https:\/\/web.archive.org\/web\/20080115093824\/http:\/\/www.theage.com.au\/news\/tv--radio\/sum-thing-to-do-with-maths-genius\/2006\/01\/05\/1136387564868.html). *The Age*. Melbourne. Archived from [the original](http:\/\/www.theage.com.au\/news\/tv--radio\/sum-thing-to-do-with-maths-genius\/2006\/01\/05\/1136387564868.html) on January 15, 2008. Retrieved August 28, 2007.\n61. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-61)**\n    [Singh, Simon](https:\/\/en.wikipedia.org\/wiki\/Simon_Singh \"Simon Singh\") (October 2014). [\"Theories of quantum levity\"](https:\/\/iopscience.iop.org\/article\/10.1088\/2058-7058\/27\/10\/41). *Physics World*. **27** (10): 80. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2014PhyW...27j..80S](https:\/\/ui.adsabs.harvard.edu\/abs\/2014PhyW...27j..80S). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1088\/2058-7058\/27\/10\/41](https:\/\/doi.org\/10.1088%2F2058-7058%2F27%2F10%2F41). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0953-8585](https:\/\/search.worldcat.org\/issn\/0953-8585).\n62. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-62)**\n    [\"The Famous Schrodinger's Cat Thought Experiment Gets Brought to Life in an Off-Kilter Animation\"](https:\/\/web.archive.org\/web\/20221202230558\/https:\/\/www.openculture.com\/2017\/03\/the-famous-schrodingers-cat-thought-experiment-gets-brought-to-life-in-an-off-kilter-animation.html). *Open Culture*. March 24, 2017. Archived from [the original](https:\/\/www.openculture.com\/2017\/03\/the-famous-schrodingers-cat-thought-experiment-gets-brought-to-life-in-an-off-kilter-animation.html) on December 2, 2022. Retrieved December 2, 2022.\n63. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-63)**\n    [\"NIGHTMARE シュレーディンガーナイフ 歌詞 – 歌詞探索【歌詞リリ】\"](https:\/\/web.archive.org\/web\/20230528210243\/https:\/\/www.lyrical-nonsense.com\/lyrics\/nightmare\/shrodinger-knife\/). *Lyrical Nonsense*. Archived from [the original](https:\/\/www.lyrical-nonsense.com\/lyrics\/nightmare\/shrodinger-knife\/) on May 28, 2023. Retrieved May 28, 2023.\n## Further reading\n- [Einstein, Albert](https:\/\/en.wikipedia.org\/wiki\/Albert_Einstein \"Albert Einstein\"); [Podolsky, Boris](https:\/\/en.wikipedia.org\/wiki\/Boris_Podolsky \"Boris Podolsky\"); [Rosen, Nathan](https:\/\/en.wikipedia.org\/wiki\/Nathan_Rosen \"Nathan Rosen\") (May 15, 1935). [\"Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?\"](https:\/\/doi.org\/10.1103%2FPhysRev.47.777). *Physical Review*. **47** (10): 777–780\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1935PhRv...47..777E](https:\/\/ui.adsabs.harvard.edu\/abs\/1935PhRv...47..777E). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/PhysRev.47.777](https:\/\/doi.org\/10.1103%2FPhysRev.47.777).\n- Leggett, Tony (August 2000). [\"New Life for Schrödinger's Cat\"](https:\/\/jrfriedman.people.amherst.edu\/Leggett%20Physics%20World%20article\/PW%20article.pdf) (PDF). Physics World. pp. 23–24. Retrieved February 28, 2020.\n  An article on experiments with \"cat state\" superpositions in superconducting rings, in which the electrons go around the ring in two directions simultaneously.\n- Trimmer, John D. (1980). \"The Present Situation in Quantum Mechanics: A Translation of Schrödinger's \"Cat Paradox\" Paper\". *[Proceedings of the American Philosophical Society](https:\/\/en.wikipedia.org\/wiki\/Proceedings_of_the_American_Philosophical_Society \"Proceedings of the American Philosophical Society\")*. **124** (5): 323–338\\. [JSTOR](https:\/\/en.wikipedia.org\/wiki\/JSTOR_\\(identifier\\) \"JSTOR (identifier)\") [986572](https:\/\/www.jstor.org\/stable\/986572).\n  ([registration required](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Verifiability#Access_to_sources \"Wikipedia:Verifiability\"))\n- Yam, Phillip (October 9, 2012). [\"Bringing Schrödinger's Cat to Life\"](https:\/\/www.scientificamerican.com\/article\/bringing-schrodingers-quantum-cat-to-life\/). *Scientific American*. Retrieved February 28, 2020.\n  A description of investigations of quantum \"cat states\" and wave function collapse by [Serge Haroche](https:\/\/en.wikipedia.org\/wiki\/Serge_Haroche \"Serge Haroche\") and [David J. Wineland](https:\/\/en.wikipedia.org\/wiki\/David_J._Wineland \"David J. Wineland\"), for which they won the 2012 [Nobel Prize in Physics](https:\/\/en.wikipedia.org\/wiki\/List_of_Nobel_laureates_in_Physics \"List of Nobel laureates in Physics\").\n- Violaris, M. (2023). *A Physics Lab Inside Your Head: Quantum Thought Experiments as an Educational Tool*. 2023 IEEE International Conference on Quantum Computing and Engineering (QCE). Bellevue, WA, USA. pp. 58–67\\. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[2312\\.07840](https:\/\/arxiv.org\/abs\/2312.07840). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1109\/QCE57702.2023.20325](https:\/\/doi.org\/10.1109%2FQCE57702.2023.20325).\n  Reduction of the Schrödinger's cat to a simple [quantum circuit](https:\/\/en.wikipedia.org\/wiki\/Quantum_circuit \"Quantum circuit\").\n## External links\n[![Wikimedia Commons logo](https:\/\/upload.wikimedia.org\/wikipedia\/en\/thumb\/4\/4a\/Commons-logo.svg\/40px-Commons-logo.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Commons-logo.svg)\n\nWikimedia Commons has media related to [Schrödinger's Cat](https:\/\/commons.wikimedia.org\/wiki\/Category:Schr%C3%B6dinger%27s_Cat \"commons:Category:Schrödinger's Cat\").\n\n- [A spoken word version](https:\/\/en.wikipedia.org\/wiki\/File:Schrodingers-cat.ogg \"File:Schrodingers-cat.ogg\") of this article (created from a revision of the article dated 2013-08-12).\n- *[Schrödinger's Cat](http:\/\/www.informationphilosopher.com\/solutions\/experiments\/schrodingerscat\/)* from the Information Philosopher.\n- [Schrödinger's Cat - Sixty Symbols](http:\/\/www.sixtysymbols.com\/videos\/schrodinger.htm) - a video published by the [University of Nottingham](https:\/\/en.wikipedia.org\/wiki\/University_of_Nottingham \"University of Nottingham\").\n- [Schrödinger's Cat](https:\/\/soundcloud.com\/siftpodcast\/schr-dingers-cat) - a podcast produced by Sift.\n\n| [v](https:\/\/en.wikipedia.org\/wiki\/Template:Quantum_mechanics_topics \"Template:Quantum mechanics topics\") [t](https:\/\/en.wikipedia.org\/wiki\/Template_talk:Quantum_mechanics_topics \"Template talk:Quantum mechanics topics\") [e](https:\/\/en.wikipedia.org\/wiki\/Special:EditPage\/Template:Quantum_mechanics_topics \"Special:EditPage\/Template:Quantum mechanics topics\")[Quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Quantum_mechanics \"Quantum mechanics\") |   |\n|---|---|\n| Background | [Introduction](https:\/\/en.wikipedia.org\/wiki\/Introduction_to_quantum_mechanics \"Introduction to quantum mechanics\") [History](https:\/\/en.wikipedia.org\/wiki\/History_of_quantum_mechanics \"History of quantum mechanics\") [Timeline](https:\/\/en.wikipedia.org\/wiki\/Timeline_of_quantum_mechanics \"Timeline of quantum mechanics\") [Classical mechanics](https:\/\/en.wikipedia.org\/wiki\/Classical_mechanics \"Classical mechanics\") [Old quantum theory](https:\/\/en.wikipedia.org\/wiki\/Old_quantum_theory \"Old quantum theory\") [Glossary](https:\/\/en.wikipedia.org\/wiki\/Glossary_of_elementary_quantum_mechanics \"Glossary of elementary quantum mechanics\") |\n| Fundamentals | [Born rule](https:\/\/en.wikipedia.org\/wiki\/Born_rule \"Born rule\") [Bra–ket notation](https:\/\/en.wikipedia.org\/wiki\/Bra%E2%80%93ket_notation \"Bra–ket notation\") [Complementarity](https:\/\/en.wikipedia.org\/wiki\/Complementarity_\\(physics\\) \"Complementarity (physics)\") [Density matrix](https:\/\/en.wikipedia.org\/wiki\/Density_matrix \"Density matrix\") [Energy level](https:\/\/en.wikipedia.org\/wiki\/Energy_level \"Energy level\") [Ground state](https:\/\/en.wikipedia.org\/wiki\/Ground_state \"Ground state\") [Excited state](https:\/\/en.wikipedia.org\/wiki\/Excited_state \"Excited state\") [Degenerate levels](https:\/\/en.wikipedia.org\/wiki\/Degenerate_energy_levels \"Degenerate energy levels\") [Zero-point energy](https:\/\/en.wikipedia.org\/wiki\/Zero-point_energy \"Zero-point energy\") [Entanglement](https:\/\/en.wikipedia.org\/wiki\/Quantum_entanglement \"Quantum entanglement\") [Hamiltonian](https:\/\/en.wikipedia.org\/wiki\/Hamiltonian_\\(quantum_mechanics\\) \"Hamiltonian (quantum mechanics)\") [Interference](https:\/\/en.wikipedia.org\/wiki\/Wave_interference \"Wave interference\") [Decoherence](https:\/\/en.wikipedia.org\/wiki\/Quantum_decoherence \"Quantum decoherence\") [Measurement](https:\/\/en.wikipedia.org\/wiki\/Measurement_in_quantum_mechanics \"Measurement in quantum mechanics\") [Nonlocality](https:\/\/en.wikipedia.org\/wiki\/Quantum_nonlocality \"Quantum nonlocality\") [Quantum state](https:\/\/en.wikipedia.org\/wiki\/Quantum_state \"Quantum state\") [quantum jump](https:\/\/en.wikipedia.org\/wiki\/Quantum_jump \"Quantum jump\") [Superposition](https:\/\/en.wikipedia.org\/wiki\/Quantum_superposition \"Quantum superposition\") [Tunnelling](https:\/\/en.wikipedia.org\/wiki\/Quantum_tunnelling \"Quantum tunnelling\") [Scattering theory](https:\/\/en.wikipedia.org\/wiki\/Scattering#Theory \"Scattering\") [Symmetry in quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Symmetry_in_quantum_mechanics \"Symmetry in quantum mechanics\") [Uncertainty](https:\/\/en.wikipedia.org\/wiki\/Uncertainty_principle \"Uncertainty principle\") [Wave function](https:\/\/en.wikipedia.org\/wiki\/Wave_function \"Wave function\") [Collapse](https:\/\/en.wikipedia.org\/wiki\/Wave_function_collapse \"Wave function collapse\") [Wave–particle duality](https:\/\/en.wikipedia.org\/wiki\/Wave%E2%80%93particle_duality \"Wave–particle duality\") |\n| Formulations | [Formulations](https:\/\/en.wikipedia.org\/wiki\/Mathematical_formulation_of_quantum_mechanics \"Mathematical formulation of quantum mechanics\") [Heisenberg](https:\/\/en.wikipedia.org\/wiki\/Heisenberg_picture \"Heisenberg picture\") [Interaction](https:\/\/en.wikipedia.org\/wiki\/Interaction_picture \"Interaction picture\") [Matrix mechanics](https:\/\/en.wikipedia.org\/wiki\/Matrix_mechanics \"Matrix mechanics\") [Schrödinger](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger_picture \"Schrödinger picture\") [Path integral formulation](https:\/\/en.wikipedia.org\/wiki\/Path_integral_formulation \"Path integral formulation\") [Phase space](https:\/\/en.wikipedia.org\/wiki\/Phase-space_formulation \"Phase-space formulation\") |\n| Equations | [Klein–Gordon](https:\/\/en.wikipedia.org\/wiki\/Klein%E2%80%93Gordon_equation \"Klein–Gordon equation\") [Dirac](https:\/\/en.wikipedia.org\/wiki\/Dirac_equation \"Dirac equation\") [Weyl](https:\/\/en.wikipedia.org\/wiki\/Weyl_equation \"Weyl equation\") [Majorana](https:\/\/en.wikipedia.org\/wiki\/Majorana_equation \"Majorana equation\") [Rarita–Schwinger](https:\/\/en.wikipedia.org\/wiki\/Rarita%E2%80%93Schwinger_equation \"Rarita–Schwinger equation\") [Pauli](https:\/\/en.wikipedia.org\/wiki\/Pauli_equation \"Pauli equation\") [Rydberg](https:\/\/en.wikipedia.org\/wiki\/Rydberg_formula \"Rydberg formula\") [Schrödinger](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger_equation \"Schrödinger equation\") |\n| [Interpretations](https:\/\/en.wikipedia.org\/wiki\/Interpretations_of_quantum_mechanics \"Interpretations of quantum mechanics\") | [Bayesian](https:\/\/en.wikipedia.org\/wiki\/Quantum_Bayesianism \"Quantum Bayesianism\") [Consciousness causes collapse](https:\/\/en.wikipedia.org\/wiki\/Consciousness_causes_collapse \"Consciousness causes collapse\") [Consistent histories](https:\/\/en.wikipedia.org\/wiki\/Consistent_histories \"Consistent histories\") [Copenhagen](https:\/\/en.wikipedia.org\/wiki\/Copenhagen_interpretation \"Copenhagen interpretation\") [de Broglie–Bohm](https:\/\/en.wikipedia.org\/wiki\/De_Broglie%E2%80%93Bohm_theory \"De Broglie–Bohm theory\") [Ensemble](https:\/\/en.wikipedia.org\/wiki\/Ensemble_interpretation \"Ensemble interpretation\") [Hidden-variable](https:\/\/en.wikipedia.org\/wiki\/Hidden-variable_theory \"Hidden-variable theory\") [Local](https:\/\/en.wikipedia.org\/wiki\/Local_hidden-variable_theory \"Local hidden-variable theory\") [Superdeterminism](https:\/\/en.wikipedia.org\/wiki\/Superdeterminism \"Superdeterminism\") [Many-worlds](https:\/\/en.wikipedia.org\/wiki\/Many-worlds_interpretation \"Many-worlds interpretation\") [Objective collapse](https:\/\/en.wikipedia.org\/wiki\/Objective-collapse_theory \"Objective-collapse theory\") [Quantum logic](https:\/\/en.wikipedia.org\/wiki\/Quantum_logic \"Quantum logic\") [Relational](https:\/\/en.wikipedia.org\/wiki\/Relational_quantum_mechanics \"Relational quantum mechanics\") [Transactional](https:\/\/en.wikipedia.org\/wiki\/Transactional_interpretation \"Transactional interpretation\") |\n| Experiments | [Bell test](https:\/\/en.wikipedia.org\/wiki\/Bell_test \"Bell test\") [Davisson–Germer](https:\/\/en.wikipedia.org\/wiki\/Davisson%E2%80%93Germer_experiment \"Davisson–Germer experiment\") [Delayed-choice quantum eraser](https:\/\/en.wikipedia.org\/wiki\/Delayed-choice_quantum_eraser \"Delayed-choice quantum eraser\") [Double-slit](https:\/\/en.wikipedia.org\/wiki\/Double-slit_experiment \"Double-slit experiment\") [Franck–Hertz](https:\/\/en.wikipedia.org\/wiki\/Franck%E2%80%93Hertz_experiment \"Franck–Hertz experiment\") [Mach–Zehnder interferometer](https:\/\/en.wikipedia.org\/wiki\/Mach%E2%80%93Zehnder_interferometer \"Mach–Zehnder interferometer\") [Elitzur–Vaidman](https:\/\/en.wikipedia.org\/wiki\/Elitzur%E2%80%93Vaidman_bomb_tester \"Elitzur–Vaidman bomb tester\") [Popper](https:\/\/en.wikipedia.org\/wiki\/Popper%27s_experiment \"Popper's experiment\") [Quantum eraser](https:\/\/en.wikipedia.org\/wiki\/Quantum_eraser_experiment \"Quantum eraser experiment\") [Stern–Gerlach](https:\/\/en.wikipedia.org\/wiki\/Stern%E2%80%93Gerlach_experiment \"Stern–Gerlach experiment\") [Wheeler's delayed choice](https:\/\/en.wikipedia.org\/wiki\/Wheeler%27s_delayed-choice_experiment \"Wheeler's delayed-choice experiment\") |\n| [Science](https:\/\/en.wikipedia.org\/wiki\/Nanotechnology \"Nanotechnology\") | [Quantum biology](https:\/\/en.wikipedia.org\/wiki\/Quantum_biology \"Quantum biology\") [Quantum chemistry](https:\/\/en.wikipedia.org\/wiki\/Quantum_chemistry \"Quantum chemistry\") [Quantum chaos](https:\/\/en.wikipedia.org\/wiki\/Quantum_chaos \"Quantum chaos\") [Quantum cosmology](https:\/\/en.wikipedia.org\/wiki\/Quantum_cosmology \"Quantum cosmology\") [Quantum differential calculus](https:\/\/en.wikipedia.org\/wiki\/Quantum_differential_calculus \"Quantum differential calculus\") [Quantum dynamics](https:\/\/en.wikipedia.org\/wiki\/Quantum_dynamics \"Quantum dynamics\") [Quantum geometry](https:\/\/en.wikipedia.org\/wiki\/Quantum_geometry \"Quantum geometry\") [Quantum measurement problem](https:\/\/en.wikipedia.org\/wiki\/Measurement_problem \"Measurement problem\") [Quantum mind](https:\/\/en.wikipedia.org\/wiki\/Quantum_mind \"Quantum mind\") [Quantum stochastic calculus](https:\/\/en.wikipedia.org\/wiki\/Quantum_stochastic_calculus \"Quantum stochastic calculus\") [Quantum spacetime](https:\/\/en.wikipedia.org\/wiki\/Quantum_spacetime \"Quantum spacetime\") |\n| [Technology](https:\/\/en.wikipedia.org\/wiki\/Quantum_engineering \"Quantum engineering\") | [Quantum algorithms](https:\/\/en.wikipedia.org\/wiki\/Quantum_algorithm \"Quantum algorithm\") [Quantum amplifier](https:\/\/en.wikipedia.org\/wiki\/Quantum_amplifier \"Quantum amplifier\") [Quantum bus](https:\/\/en.wikipedia.org\/wiki\/Quantum_bus \"Quantum bus\") [Quantum cellular automata](https:\/\/en.wikipedia.org\/wiki\/Quantum_cellular_automaton \"Quantum cellular automaton\") [Quantum finite automata](https:\/\/en.wikipedia.org\/wiki\/Quantum_finite_automaton \"Quantum finite automaton\") [Quantum channel](https:\/\/en.wikipedia.org\/wiki\/Quantum_channel \"Quantum channel\") [Quantum circuit](https:\/\/en.wikipedia.org\/wiki\/Quantum_circuit \"Quantum circuit\") [Quantum complexity theory](https:\/\/en.wikipedia.org\/wiki\/Quantum_complexity_theory \"Quantum complexity theory\") [Quantum computing](https:\/\/en.wikipedia.org\/wiki\/Quantum_computing \"Quantum computing\") [Timeline](https:\/\/en.wikipedia.org\/wiki\/Timeline_of_quantum_computing_and_communication \"Timeline of quantum computing and communication\") [Quantum cryptography](https:\/\/en.wikipedia.org\/wiki\/Quantum_cryptography \"Quantum cryptography\") [Quantum electronics](https:\/\/en.wikipedia.org\/wiki\/Quantum_optics#Quantum_electronics \"Quantum optics\") [Quantum error correction](https:\/\/en.wikipedia.org\/wiki\/Quantum_error_correction \"Quantum error correction\") [Quantum imaging](https:\/\/en.wikipedia.org\/wiki\/Quantum_imaging \"Quantum imaging\") [Quantum image processing](https:\/\/en.wikipedia.org\/wiki\/Quantum_image_processing \"Quantum image processing\") [Quantum information](https:\/\/en.wikipedia.org\/wiki\/Quantum_information \"Quantum information\") [Quantum key distribution](https:\/\/en.wikipedia.org\/wiki\/Quantum_key_distribution \"Quantum key distribution\") [Quantum logic](https:\/\/en.wikipedia.org\/wiki\/Quantum_logic \"Quantum logic\") [Quantum logic gates](https:\/\/en.wikipedia.org\/wiki\/Quantum_logic_gate \"Quantum logic gate\") [Quantum machine](https:\/\/en.wikipedia.org\/wiki\/Quantum_machine \"Quantum machine\") [Quantum machine learning](https:\/\/en.wikipedia.org\/wiki\/Quantum_machine_learning \"Quantum machine learning\") [Quantum metamaterial](https:\/\/en.wikipedia.org\/wiki\/Quantum_metamaterial \"Quantum metamaterial\") [Quantum metrology](https:\/\/en.wikipedia.org\/wiki\/Quantum_metrology \"Quantum metrology\") [Quantum network](https:\/\/en.wikipedia.org\/wiki\/Quantum_network \"Quantum network\") [Quantum neural network](https:\/\/en.wikipedia.org\/wiki\/Quantum_neural_network \"Quantum neural network\") [Quantum optics](https:\/\/en.wikipedia.org\/wiki\/Quantum_optics \"Quantum optics\") [Quantum programming](https:\/\/en.wikipedia.org\/wiki\/Quantum_programming \"Quantum programming\") [Quantum sensing](https:\/\/en.wikipedia.org\/wiki\/Quantum_sensor \"Quantum sensor\") [Quantum simulator](https:\/\/en.wikipedia.org\/wiki\/Quantum_simulator \"Quantum simulator\") [Quantum teleportation](https:\/\/en.wikipedia.org\/wiki\/Quantum_teleportation \"Quantum teleportation\") |\n| Extensions | [Quantum fluctuation](https:\/\/en.wikipedia.org\/wiki\/Quantum_fluctuation \"Quantum fluctuation\") [Casimir effect](https:\/\/en.wikipedia.org\/wiki\/Casimir_effect \"Casimir effect\") [Quantum statistical mechanics](https:\/\/en.wikipedia.org\/wiki\/Quantum_statistical_mechanics \"Quantum statistical mechanics\") [Quantum field theory](https:\/\/en.wikipedia.org\/wiki\/Quantum_field_theory \"Quantum field theory\") [History](https:\/\/en.wikipedia.org\/wiki\/History_of_quantum_field_theory \"History of quantum field theory\") [Quantum gravity](https:\/\/en.wikipedia.org\/wiki\/Quantum_gravity \"Quantum gravity\") [Relativistic quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Relativistic_quantum_mechanics \"Relativistic quantum mechanics\") |\n| Related | [Schrödinger's cat]() [in popular culture](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat_in_popular_culture \"Schrödinger's cat in popular culture\") [Wigner's friend](https:\/\/en.wikipedia.org\/wiki\/Wigner%27s_friend \"Wigner's friend\") [EPR paradox](https:\/\/en.wikipedia.org\/wiki\/Einstein%E2%80%93Podolsky%E2%80%93Rosen_paradox \"Einstein–Podolsky–Rosen paradox\") [Quantum mysticism](https:\/\/en.wikipedia.org\/wiki\/Quantum_mysticism \"Quantum mysticism\") |\n| ![](https:\/\/upload.wikimedia.org\/wikipedia\/en\/thumb\/9\/96\/Symbol_category_class.svg\/20px-Symbol_category_class.svg.png) [Category](https:\/\/en.wikipedia.org\/wiki\/Category:Quantum_mechanics \"Category:Quantum mechanics\") |   |\n\n|   |   |\n|---|---|\n| [Authority control databases](https:\/\/en.wikipedia.org\/wiki\/Help:Authority_control \"Help:Authority control\"): National [![Edit this at Wikidata](https:\/\/upload.wikimedia.org\/wikipedia\/en\/thumb\/8\/8a\/OOjs_UI_icon_edit-ltr-progressive.svg\/20px-OOjs_UI_icon_edit-ltr-progressive.svg.png)](https:\/\/www.wikidata.org\/wiki\/Q8588#identifiers \"Edit this at Wikidata\") | 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Wikipedia® is a registered trademark of the [Wikimedia Foundation, Inc.](https:\/\/wikimediafoundation.org\/), a non-profit organization.\n\n- [Privacy policy](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Privacy_policy)\n- [About Wikipedia](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:About)\n- [Disclaimers](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:General_disclaimer)\n- [Contact Wikipedia](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Contact_us)\n- [Legal & safety contacts](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Legal:Wikimedia_Foundation_Legal_and_Safety_Contact_Information)\n- [Code of Conduct](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Universal_Code_of_Conduct)\n- [Developers](https:\/\/developer.wikimedia.org\/)\n- [Statistics](https:\/\/stats.wikimedia.org\/#\/en.wikipedia.org)\n- [Cookie statement](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Cookie_statement)\n- [Mobile view](https:\/\/en.wikipedia.org\/w\/index.php?title=Schr%C3%B6dinger%27s_cat&mobileaction=toggle_view_mobile)\n\n- [![Wikimedia Foundation](https:\/\/en.wikipedia.org\/static\/images\/footer\/wikimedia.svg)](https:\/\/www.wikimedia.org\/)\n- [![Powered by MediaWiki](https:\/\/en.wikipedia.org\/w\/resources\/assets\/mediawiki_compact.svg)](https:\/\/www.mediawiki.org\/)\n\nSearch\n\nToggle the table of contents\n\nSchrödinger's cat\n\n79 languages\n\n[Add topic](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat)","attrs_readable_markdown":"[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/9\/91\/Schrodingers_cat.svg\/500px-Schrodingers_cat.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Schrodingers_cat.svg)\n\nSchrödinger's cat: a cat, a flask of poison, and a [radioactive](https:\/\/en.wikipedia.org\/wiki\/Radioactive \"Radioactive\") source connected to a [Geiger counter](https:\/\/en.wikipedia.org\/wiki\/Geiger_counter \"Geiger counter\") are placed in a sealed box. As illustrated, the quantum description uses a superposition of an alive cat and one that has died.\n\nIn [quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Quantum_mechanics \"Quantum mechanics\"), **Schrödinger's cat** is a [thought experiment](https:\/\/en.wikipedia.org\/wiki\/Thought_experiment \"Thought experiment\") concerning [quantum superposition](https:\/\/en.wikipedia.org\/wiki\/Quantum_superposition \"Quantum superposition\"). In the thought experiment, a hypothetical [cat](https:\/\/en.wikipedia.org\/wiki\/Cat \"Cat\") in a closed box may be considered to be simultaneously both alive and dead while it is unobserved, as a result of its fate being linked to a random [subatomic](https:\/\/en.wikipedia.org\/wiki\/Subatomic_particle \"Subatomic particle\") event that may or may not occur. This experiment, viewed this way, is described as a [paradox](https:\/\/en.wikipedia.org\/wiki\/Paradox \"Paradox\"). This thought experiment was devised by physicist [Erwin Schrödinger](https:\/\/en.wikipedia.org\/wiki\/Erwin_Schr%C3%B6dinger \"Erwin Schrödinger\") in 1935,[\\[1\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1) in a discussion with [Albert Einstein](https:\/\/en.wikipedia.org\/wiki\/Albert_Einstein \"Albert Einstein\"),[\\[2\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Fine-2) to illustrate what Schrödinger saw as the problems of [Niels Bohr](https:\/\/en.wikipedia.org\/wiki\/Niels_Bohr \"Niels Bohr\") and [Werner Heisenberg](https:\/\/en.wikipedia.org\/wiki\/Werner_Heisenberg \"Werner Heisenberg\")'s philosophical views on quantum mechanics.\n\nIn Schrödinger's original formulation, a cat, a flask of poison, and a [radioactive](https:\/\/en.wikipedia.org\/wiki\/Radioactive \"Radioactive\") source are placed in a sealed box. If an internal radiation monitor such as a [Geiger counter](https:\/\/en.wikipedia.org\/wiki\/Geiger_counter \"Geiger counter\") detects radioactivity (a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. If no decaying atom triggers the monitor, the cat remains alive. Mathematically, the [wave function](https:\/\/en.wikipedia.org\/wiki\/Wave_function \"Wave function\") that describes the contents of the box is a combination, or [quantum superposition](https:\/\/en.wikipedia.org\/wiki\/Quantum_superposition \"Quantum superposition\"), of these two possibilities. Yet, when one looks in the box, one sees the cat *either* alive *or* dead, not both alive *and* dead. This poses the question of when exactly quantum superposition ends and reality resolves into one possibility or the other.\n\nAlthough originally a critique of Bohr and Heisenberg, Schrödinger's seemingly paradoxical thought experiment became part of the foundation of quantum mechanics. It is often featured in theoretical discussions of the [interpretations of quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Interpretations_of_quantum_mechanics \"Interpretations of quantum mechanics\"), particularly in situations involving the [measurement problem](https:\/\/en.wikipedia.org\/wiki\/Measurement_problem \"Measurement problem\"). As a result, Schrödinger's cat has had enduring [appeal in popular culture](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat_in_popular_culture \"Schrödinger's cat in popular culture\"). The experiment is not intended to be actually performed on a cat, but rather as an easily understandable illustration of the behavior of atoms. Experiments at the atomic scale have been carried out, showing that very small objects may exist as superpositions, but superposing an object as large as a cat would pose considerable technical difficulties.[\\[3\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-3)\n\nFundamentally, the Schrödinger's cat experiment asks how long quantum superpositions last and when (or whether) they collapse. Different [interpretations of the mathematics of quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Interpretations_of_quantum_mechanics \"Interpretations of quantum mechanics\") have been proposed that give different explanations for this process.\n\nOrigin and motivation\n\nUnsolved problem in physics\n\nHow does the quantum description of reality, which includes elements such as the superposition of states and wavefunction collapse or quantum decoherence, give rise to the reality we perceive? Another way of stating this question regards the measurement problem: What constitutes a \"measurement\" that apparently causes the wave function to collapse into a definite state?\n\nSchrödinger intended his thought experiment as a discussion of the [EPR article](https:\/\/en.wikipedia.org\/wiki\/Einstein%E2%80%93Podolsky%E2%80%93Rosen_paradox \"Einstein–Podolsky–Rosen paradox\")—named after its authors [Einstein](https:\/\/en.wikipedia.org\/wiki\/Albert_Einstein \"Albert Einstein\"), [Podolsky](https:\/\/en.wikipedia.org\/wiki\/Boris_Podolsky \"Boris Podolsky\"), and [Rosen](https:\/\/en.wikipedia.org\/wiki\/Nathan_Rosen \"Nathan Rosen\")—in 1935.[\\[4\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-4)[\\[5\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5) The EPR article highlighted the counterintuitive nature of [quantum superpositions](https:\/\/en.wikipedia.org\/wiki\/Quantum_superposition \"Quantum superposition\"), in which a quantum system for two particles does not separate[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 150  even when the particles are detected far from their last point of contact. The EPR paper concludes with a claim that this lack of separability meant that quantum mechanics as a theory of reality was incomplete.\n\nSchrödinger and Einstein exchanged letters about Einstein's EPR article, in the course of which Einstein pointed out that the state of an [unstable](https:\/\/en.wikipedia.org\/wiki\/Unstable \"Unstable\") keg of [gunpowder](https:\/\/en.wikipedia.org\/wiki\/Gunpowder \"Gunpowder\") will, after a while, contain a superposition of both exploded and unexploded states.[\\[5\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5) To further illustrate, Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a closed steel chamber, wherein the cat's life or death depended on the state of a [radioactive](https:\/\/en.wikipedia.org\/wiki\/Radioactive \"Radioactive\") atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the position taken by Bohr and Heisenberg would be that *the cat remains both alive and dead* until the state has been observed. Schrödinger did not wish to promote the idea of dead-and-live cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics,[\\[1\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1) thus employing *[reductio ad absurdum](https:\/\/en.wikipedia.org\/wiki\/Reductio_ad_absurdum \"Reductio ad absurdum\")*.\n\nSince Schrödinger's time, various [interpretations of the mathematics of quantum mechanics](https:\/\/en.wikipedia.org\/wiki\/Interpretations_of_quantum_mechanics \"Interpretations of quantum mechanics\") have been advanced by physicists, some of which regard the \"alive and dead\" cat superposition as quite real, while others do not.[\\[7\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Polkinghorne-7)[\\[8\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Tetlow-8) Intended as a critique of ideas prevalent in 1935, the Schrödinger's cat thought experiment remains a [touchstone](https:\/\/en.wikipedia.org\/wiki\/Touchstone_\\(metaphor\\) \"Touchstone (metaphor)\") for modern interpretations of quantum mechanics and can be used to illustrate and compare their strengths and weaknesses.[\\[9\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-9)\\[*[better source needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Verifiability#Questionable_sources \"Wikipedia:Verifiability\")*\\]\n\nThought experiment\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/5e\/Schroedinger_cat.jpg\/330px-Schroedinger_cat.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Schroedinger_cat.jpg)\n\nA life-size cat figure in the garden of Huttenstrasse 9, Zurich, where [Erwin Schrödinger](https:\/\/en.wikipedia.org\/wiki\/Erwin_Schr%C3%B6dinger \"Erwin Schrödinger\") lived from 1921 to 1926. Depending on the light conditions, the figure appears to be either a live cat or a dead one.\n\nSchrödinger wrote:[\\[1\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1)[\\[10\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-10)\n\n> One can contrive even completely burlesque \\[farcical\\] cases. A cat is put in a steel chamber along with the following infernal device (which must be secured against direct interference by the cat): in a [Geiger counter](https:\/\/en.wikipedia.org\/wiki\/Geiger_counter \"Geiger counter\"), there is a tiny amount of radioactive substance, so tiny that in the course of an hour one of the atoms will perhaps decay, but also, with equal probability, that none of them will; if it does happen, the counter tube will discharge and through a relay release a hammer that will shatter a small flask of [hydrocyanic acid](https:\/\/en.wikipedia.org\/wiki\/Hydrocyanic_acid \"Hydrocyanic acid\"). If one has left this entire system to itself for an hour, one would tell oneself that the cat is still alive if no atom has [decayed](https:\/\/en.wikipedia.org\/wiki\/Radioactive_decay \"Radioactive decay\") in the meantime. Even a single atomic decay would have poisoned it. The [psi-function](https:\/\/en.wikipedia.org\/wiki\/Wave_function \"Wave function\") of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or spread out in equal parts.\n> \n> It is typical of these cases that an indeterminacy originally restricted to the atomic domain turns into a sensually observable \\[macroscopic\\] indeterminacy, which can then be resolved by direct observation. This prevents us from so naïvely accepting a \"blurred model\" as representative of reality. Per se, it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks.\n\nSchrödinger developed his famous [thought experiment](https:\/\/en.wikipedia.org\/wiki\/Thought_experiment \"Thought experiment\") in correspondence with Einstein. He suggested this 'quite ridiculous case' to illustrate his conclusion that the wave function cannot represent reality.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 153  The wave function description of the complete cat system implies that the reality of the cat mixes the living and dead cat.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 154  Einstein was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote:[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 157\n\n> You are the only contemporary physicist, besides [Laue](https:\/\/en.wikipedia.org\/wiki\/Max_von_Laue \"Max von Laue\"), who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gun powder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation.[\\[11\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-11)\n\nNote that the charge of gunpowder is not mentioned in Schrödinger's setup, which uses a Geiger counter as an amplifier and hydrocyanic poison instead of gunpowder. The gunpowder had been mentioned in Einstein's original suggestion to Schrödinger 15 years before, and Einstein carried it forward to the present discussion.[\\[5\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5)\n\nAnalysis\n\nIn modern terms Schrödinger's hypothetical cat experiment describes the [measurement problem](https:\/\/en.wikipedia.org\/wiki\/Measurement_problem \"Measurement problem\"): quantum theory describes the cat system as a combination of two possible outcomes but only one outcome is ever observed.[\\[12\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-PeresCat-12): 57 [\\[13\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-SchlosshauerDecoherenceReview-13): 1269  The experiment poses the question, \"*when* does a quantum system stop existing as a superposition of states and become one or the other?\" (More technically, when does the actual quantum state stop being a non-trivial [linear combination](https:\/\/en.wikipedia.org\/wiki\/Linear_combination \"Linear combination\") of states, each of which resembles different classical states, and instead begin to have a unique classical description?) Standard microscopic quantum mechanics describes multiple possible outcomes of experiments but only one outcome is observed. The thought experiment illustrates this apparent paradox. Our intuition says that the cat cannot be in more than one state simultaneously—yet the quantum mechanical description of the thought experiment requires such a condition.\n\nInterpretations\n\nSince Schrödinger's time, other interpretations of quantum mechanics have been proposed that give different answers to the questions posed by Schrödinger's cat of how long superpositions last and when (or *whether*) they collapse.\n\nCopenhagen interpretation\n\nA commonly held interpretation of quantum mechanics is the Copenhagen interpretation.[\\[14\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Wimmel1992-14) In the Copenhagen interpretation, a measurement results in only one state of a superposition. This thought experiment makes apparent the fact that this interpretation simply provides no explanation for the state of the cat while the box is closed. The wavefunction description of the system consists of a superposition of the states \"decayed nucleus\/dead cat\" and \"undecayed nucleus\/living cat\". Only when the box is opened and observed can we make a statement about the cat.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 157\n\nRole of consciousness\n\nIn 1932, [John von Neumann](https:\/\/en.wikipedia.org\/wiki\/John_von_Neumann \"John von Neumann\") described in his book *[Mathematical Foundations of Quantum Mechanics](https:\/\/en.wikipedia.org\/wiki\/Mathematical_Foundations_of_Quantum_Mechanics \"Mathematical Foundations of Quantum Mechanics\")* a pattern where the radioactive source is observed by a device, which itself is observed by another device and so on. It makes no difference in the predictions of quantum theory where along this chain of causal effects the superposition collapses.[\\[15\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Tales_of_the_Quantum-15) This potentially infinite chain could be broken if the last device is replaced by a conscious observer. This solved the problem because it was claimed that an individual's consciousness cannot be multiple.[\\[16\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-16) Eugene Wigner asserted that an observer is necessary for a collapse to one or the other (e.g., either a live cat or a dead cat) of the terms on the right-hand side of a [wave function](https:\/\/en.wikipedia.org\/wiki\/Wave_function \"Wave function\"). Wigner discussed the interpretation in a thought experiment known as [Wigner's friend](https:\/\/en.wikipedia.org\/wiki\/Wigner%27s_friend \"Wigner's friend\").[\\[17\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Surfing_the_Quantum_World-17) Wigner supposed that a friend opened the box and observed the cat without telling anyone. From Wigner's conscious perspective, the friend is now part of the wave function and has seen a live cat and seen a dead cat. To a third person's conscious perspective, Wigner himself becomes part of the wave function once Wigner learns the outcome from the friend. This could be extended indefinitely.[\\[17\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Surfing_the_Quantum_World-17)\n\nA resolution of the paradox is that the triggering of the Geiger counter counts as a measurement of the state of the radioactive substance. Because a measurement has already occurred deciding the state of the cat, the subsequent observation by a human records only what has already occurred.[\\[18\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-18) Analysis of an actual experiment by [Roger Carpenter](https:\/\/en.wikipedia.org\/wiki\/Roger_Carpenter \"Roger Carpenter\") and A. J. Anderson found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before any human knows of the result.[\\[19\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Carpenter2006-19) The apparatus indicates one of two colors depending on the outcome. The human observer sees which color is indicated, but does not consciously know which outcome the color represents. A second human, the one who set up the apparatus, is told of the color and becomes conscious of the outcome, and the box is opened to check if the outcome matches.[\\[15\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Tales_of_the_Quantum-15) However, it is disputed whether merely observing the color counts as a conscious observation of the outcome.[\\[20\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Okon2006-20)\n\nBohr's interpretation\n\nAnalysis of the work of [Niels Bohr](https:\/\/en.wikipedia.org\/wiki\/Niels_Bohr \"Niels Bohr\"), one of the main scientists associated with the Copenhagen interpretation, suggests he viewed the state of the cat before the box is opened as indeterminate. The superposition itself had no physical meaning to Bohr: Schrödinger's cat would be either dead or alive long before the box is opened but the cat and box form an inseparable combination.[\\[21\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Faye2008-21) Bohr saw no role for a human observer.[\\[22\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-22): 35  Bohr emphasized the classical nature of measurement results. An \"irreversible\" or effectively irreversible process imparts the classical behavior of \"observation\" or \"measurement\".[\\[23\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-23)[\\[24\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-24)[\\[25\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-25)\n\nMany-worlds interpretation\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/c\/c8\/Schroedingers_cat_film.svg\/250px-Schroedingers_cat_film.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Schroedingers_cat_film.svg)\n\nThe quantum-mechanical \"Schrödinger's cat\" paradox according to the many-worlds interpretation. In this interpretation, every event is a branch point. The cat is both alive and dead—regardless of whether the box is opened—but the \"alive\" and \"dead\" cats are in different branches of the universe that are equally real but cannot interact with each other.\n\nIn 1957, [Hugh Everett](https:\/\/en.wikipedia.org\/wiki\/Hugh_Everett \"Hugh Everett\") formulated the many-worlds interpretation of quantum mechanics, which does not single out observation as a special process. In the many-worlds interpretation, both alive and dead states of the cat persist after the box is opened, but are [decoherent](https:\/\/en.wikipedia.org\/wiki\/Quantum_decoherence \"Quantum decoherence\") from each other. In other words, when the box is opened, the observer and the possibly-dead cat split into an observer looking at a box with a dead cat and an observer looking at a box with a live cat. But since the dead and alive states are decoherent, there is no communication or interaction between them.\n\nWhen opening the box, the observer becomes entangled with the cat, so \"observer states\" corresponding to the cat's being alive and dead are formed; each observer state is [entangled](https:\/\/en.wikipedia.org\/wiki\/Quantum_entanglement \"Quantum entanglement\"), or linked, with the cat so that the observation of the cat's state and the cat's state correspond with each other. Quantum decoherence ensures that the different outcomes have no interaction with each other. Decoherence is generally considered to prevent simultaneous observation of multiple states.[\\[26\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-zurek03-26)[\\[27\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-zurek91-27)\n\nA variant of the Schrödinger's cat experiment, known as the [quantum suicide](https:\/\/en.wikipedia.org\/wiki\/Quantum_suicide_and_immortality \"Quantum suicide and immortality\") machine, has been proposed by cosmologist [Max Tegmark](https:\/\/en.wikipedia.org\/wiki\/Max_Tegmark \"Max Tegmark\"). It examines the Schrödinger's cat experiment from the point of view of the cat, and argues that by using this approach, one may be able to distinguish between the Copenhagen interpretation and many-worlds.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nEnsemble interpretation\n\nIn [Ensemble interpretations](https:\/\/en.wikipedia.org\/wiki\/Ensemble_interpretation \"Ensemble interpretation\"), superpositions are sub-ensembles of a larger statistical ensemble. The state vector would not apply to individual cat experiments, but only to the statistics of many similarly prepared cat experiments. Proponents of these interpretations argue that this makes the Schrödinger's cat paradox a trivial matter, or a non-issue. When the physicist opens the box, they simply discover which subensemble that specific cat belonged to.[\\[28\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-28)\n\nRelational interpretation\n\nThe [relational interpretation](https:\/\/en.wikipedia.org\/wiki\/Relational_quantum_mechanics \"Relational quantum mechanics\") makes no fundamental distinction between the human experimenter, the cat, and the apparatus or between animate and inanimate systems; all are quantum systems governed by the same rules of wavefunction [evolution](https:\/\/en.wikipedia.org\/wiki\/Time_evolution \"Time evolution\"), and all may be considered \"observers\". But the relational interpretation allows that different observers can give different accounts of the same series of events, depending on the information they have about the system.[\\[29\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-29)\\[*[non-primary source needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources \"Wikipedia:No original research\")*\\] The cat can be considered an observer of the apparatus; meanwhile, the experimenter can be considered another observer of the system in the box (the cat plus the apparatus). Before the box is opened, the cat, by nature of its being alive or dead, has information about the state of the apparatus (the atom has either decayed or not decayed); but the experimenter does not have information about the state of the box contents. In this way, the two observers simultaneously have different accounts of the situation: To the cat, the wavefunction of the apparatus has appeared to \"collapse\"; to the experimenter, the contents of the box appear to be in superposition. Not until the box is opened, and both observers have the same information about what happened, do both system states appear to \"collapse\" into the same definite result, a cat that is either alive or dead.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nTransactional interpretation\n\nIn the [transactional interpretation](https:\/\/en.wikipedia.org\/wiki\/Transactional_interpretation \"Transactional interpretation\") the apparatus emits an advanced wave backward in time, which combined with the wave that the source emits forward in time, forms a standing wave. The waves are seen as physically real, and the apparatus is considered an \"observer\". In the transactional interpretation, the collapse of the wavefunction is \"atemporal\" and occurs along the whole transaction between the source and the apparatus. The cat is never in superposition. Rather the cat is only in one state at any particular time, regardless of when the human experimenter looks in the box. The transactional interpretation resolves this quantum paradox.[\\[30\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-30)\\[*[non-primary source needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources \"Wikipedia:No original research\")*\\]\n\nObjective collapse theories\n\nAccording to [objective collapse theories](https:\/\/en.wikipedia.org\/wiki\/Objective-collapse_theory \"Objective-collapse theory\"), superpositions are destroyed spontaneously (irrespective of external observation) when some objective physical threshold (of time, mass, temperature, [irreversibility](https:\/\/en.wikipedia.org\/wiki\/Irreversibility \"Irreversibility\"), etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is opened. This could loosely be phrased as \"the cat observes itself\" or \"the environment observes the cat\".\n\nObjective collapse theories require a modification of standard quantum mechanics to allow superpositions to be destroyed by the process of time evolution.[\\[31\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-31) These theories could ideally be tested by creating mesoscopic superposition states in the experiment. For instance, energy cat states have been proposed as a precise detector of the quantum gravity related energy decoherence models.[\\[32\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-32)\n\nApplications and tests\n\nSchrödinger's cat quantum superposition of states and effect of the environment through decoherence\n\nThe experiment as described is a purely theoretical one, and the machine proposed is not known to have been constructed. However, successful experiments involving similar principles, e.g. superpositions of [relatively large](https:\/\/en.wikipedia.org\/wiki\/Mesoscopic \"Mesoscopic\") (by the standards of quantum physics) objects have been performed.[\\[33\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-33)\\[*[better source needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Verifiability#Questionable_sources \"Wikipedia:Verifiability\")*\\] These experiments do not show that a cat-sized object can be superposed, but the known upper limit on \"[cat states](https:\/\/en.wikipedia.org\/wiki\/Cat_state \"Cat state\")\" has been pushed upwards by them. In many cases the state is short-lived, even when cooled to near [absolute zero](https:\/\/en.wikipedia.org\/wiki\/Absolute_zero \"Absolute zero\").\n\n- A \"cat state\" has been achieved with photons.[\\[34\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-34)[\\[35\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-35)\n- A beryllium ion has been trapped in a superposed state.[\\[36\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-36)\n- An experiment involving a [superconducting quantum interference device](https:\/\/en.wikipedia.org\/wiki\/Superconducting_quantum_interference_device \"Superconducting quantum interference device\") (\"SQUID\") has been linked to the theme of the thought experiment: \"The superposition state does not correspond to a billion electrons flowing one way and a billion others flowing the other way. Superconducting electrons move en masse. All the superconducting electrons in the SQUID flow both ways around the loop at once when they are in the Schrödinger's cat state.\"[\\[37\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-37)\n- A [piezoelectric](https:\/\/en.wikipedia.org\/wiki\/Piezoelectric \"Piezoelectric\") \"tuning fork\" has been constructed, which can be placed into a superposition of vibrating and non vibrating states. The resonator comprises about 10 trillion atoms.[\\[38\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-38)\n- An experiment involving a flu virus has been proposed.[\\[39\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-39)\n- An experiment involving a bacterium and an electromechanical oscillator has been proposed.[\\[40\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-40)\n\nIn [quantum computing](https:\/\/en.wikipedia.org\/wiki\/Quantum_computing \"Quantum computing\") the phrase \"cat state\" sometimes refers to the [GHZ state](https:\/\/en.wikipedia.org\/wiki\/Greenberger%E2%80%93Horne%E2%80%93Zeilinger_state \"Greenberger–Horne–Zeilinger state\"), wherein several qubits are in an equal superposition of all being 0 and all being 1; e.g.,\n\n![{\\\\displaystyle \\|\\\\psi \\\\rangle ={\\\\frac {1}{\\\\sqrt {2}}}{\\\\bigg (}\\|00\\\\ldots 0\\\\rangle +\\|11\\\\ldots 1\\\\rangle {\\\\bigg )}.}](https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/26aac0fa72a1f19180f6d2914259cadd8f07be74)\n\nAccording to at least one proposal, it may be possible to determine the state of the cat *before* observing it.[\\[41\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-LS-20191107-41)[\\[42\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-NJP-20191001-42)\n\nIn popular culture\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/e\/ed\/SchroCat.jpg\/250px-SchroCat.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:SchroCat.jpg)\n\nThis drawing by [F. Gwynplaine MacIntyre](https:\/\/en.wikipedia.org\/wiki\/F._Gwynplaine_MacIntyre \"F. Gwynplaine MacIntyre\"), originally published in *[Analog](https:\/\/en.wikipedia.org\/wiki\/Analog_Science_Fiction_and_Fact \"Analog Science Fiction and Fact\")* magazine, illustrates MacIntyre's science-fiction story \"Schrödinger's Cat-Sitter\". The cat is depicted simultaneously in front of and behind the [impossible trident](https:\/\/en.wikipedia.org\/wiki\/Impossible_trident \"Impossible trident\") in an [optical illusion](https:\/\/en.wikipedia.org\/wiki\/Optical_illusion \"Optical illusion\").\n\nAccording to historian of science [Robert P. Crease](https:\/\/en.wikipedia.org\/wiki\/Robert_P._Crease \"Robert P. Crease\"), Schrödinger's thought experiment did not become widely known until the 1970s. In 1972 [Ursula K. Le Guin](https:\/\/en.wikipedia.org\/wiki\/Ursula_K._Le_Guin \"Ursula K. Le Guin\") learned about it while researching quantum mechanics for her novel *[The Dispossessed](https:\/\/en.wikipedia.org\/wiki\/The_Dispossessed \"The Dispossessed\")*; Crease credits her 1974 short story \"Schrödinger's Cat\" with bringing the concept into popular culture.[\\[43\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-43) Other [science-fiction](https:\/\/en.wikipedia.org\/wiki\/Science_fiction \"Science fiction\") writers soon picked it up, often using it in a humorous vein.[\\[44\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-100CCC-44) Works of fiction have employed Schrödinger's thought experiment as plot device and as [metaphor](https:\/\/en.wikipedia.org\/wiki\/Metaphor \"Metaphor\"), in genres from [apocalyptic science fiction](https:\/\/en.wikipedia.org\/wiki\/Apocalyptic_science_fiction \"Apocalyptic science fiction\") to young-adult drama, making the cat more prominent in popular culture than in physics itself.[\\[45\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Crease-45)[\\[46\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-46)[\\[47\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-47)[\\[48\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-48)\n\nSchrödinger's cat has been a motive in many science fiction works, and used as a title of a number of them, including [Greg Bear](https:\/\/en.wikipedia.org\/wiki\/Greg_Bear \"Greg Bear\")'s \"Schrödinger's Plague\" (*[Analog](https:\/\/en.wikipedia.org\/wiki\/Analog_Science_Fiction_and_Fact \"Analog Science Fiction and Fact\")*, 29 March 1982), [George Alec Effinger](https:\/\/en.wikipedia.org\/wiki\/George_Alec_Effinger \"George Alec Effinger\")'s \"[Schrödinger's Kitten](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_Kitten \"Schrödinger's Kitten\")\" (*[Omni](https:\/\/en.wikipedia.org\/wiki\/Omni_\\(magazine\\) \"Omni (magazine)\")*, September 1988), [F. Gwynplaine MacIntyre](https:\/\/en.wikipedia.org\/wiki\/F._Gwynplaine_MacIntyre \"F. Gwynplaine MacIntyre\")'s \"Schrödinger's Cat-Sitter\" (*Analog*, July\/August 2001), [Rudy Rucker](https:\/\/en.wikipedia.org\/wiki\/Rudy_Rucker \"Rudy Rucker\")'s \"Schrödinger's Cat\" (*Analog*, 30 March 1981), and [Robert Anton Wilson](https:\/\/en.wikipedia.org\/wiki\/Robert_Anton_Wilson \"Robert Anton Wilson\")'s *[Schrödinger's Cat Trilogy](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_Cat_Trilogy \"Schrödinger's Cat Trilogy\")* (1988), illustrating various [interpretations of quantum physics](https:\/\/en.wikipedia.org\/wiki\/Interpretations_of_quantum_mechanics \"Interpretations of quantum mechanics\").[\\[49\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-49)[\\[50\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-50) In addition to novels and short stories, Schrödinger's cat has appeared in film,[\\[51\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-51)[\\[52\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-52)[\\[53\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-53)[\\[54\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-54) poetry,[\\[55\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-55)[\\[56\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-56) theatre,[\\[57\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger's_Girlfriend-57)[\\[58\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Schrodingers_Girlfriend_SFG-58) live-action television,[\\[59\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-59) cartoons,[\\[60\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-The_Age-60)[\\[61\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-61)[\\[62\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-62) music,[\\[63\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-63) and webcomics.[\\[45\\]](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_note-Crease-45)\n\nSee also\n\n- [Basis function](https:\/\/en.wikipedia.org\/wiki\/Basis_function \"Basis function\")\n- [Cat state](https:\/\/en.wikipedia.org\/wiki\/Cat_state \"Cat state\")\n- [Complementarity (physics)](https:\/\/en.wikipedia.org\/wiki\/Complementarity_\\(physics\\) \"Complementarity (physics)\")\n- [Double-slit experiment](https:\/\/en.wikipedia.org\/wiki\/Double-slit_experiment \"Double-slit experiment\")\n- [Elitzur–Vaidman bomb tester](https:\/\/en.wikipedia.org\/wiki\/Elitzur%E2%80%93Vaidman_bomb_tester \"Elitzur–Vaidman bomb tester\")\n- [Heisenberg cut](https:\/\/en.wikipedia.org\/wiki\/Heisenberg_cut \"Heisenberg cut\")\n- [Modal realism](https:\/\/en.wikipedia.org\/wiki\/Modal_realism \"Modal realism\")\n- [Observer effect (physics)](https:\/\/en.wikipedia.org\/wiki\/Observer_effect_\\(physics\\) \"Observer effect (physics)\")\n- [Ray cat](https:\/\/en.wikipedia.org\/wiki\/Ray_cat \"Ray cat\")\n- [Schroedinbug](https:\/\/en.wikipedia.org\/wiki\/Schroedinbug \"Schroedinbug\")\n\nReferences\n\n1. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-1) [***c***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-2)\n   [Schrödinger, Erwin](https:\/\/en.wikipedia.org\/wiki\/Erwin_Schr%C3%B6dinger \"Erwin Schrödinger\") (November 1935). \"Die gegenwärtige Situation in der Quantenmechanik (The Present Situation in Quantum Mechanics)\". *[Naturwissenschaften](https:\/\/en.wikipedia.org\/wiki\/Naturwissenschaften \"Naturwissenschaften\")*. **23** (48): 807–812\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1935NW.....23..807S](https:\/\/ui.adsabs.harvard.edu\/abs\/1935NW.....23..807S). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1007\/BF01491891](https:\/\/doi.org\/10.1007%2FBF01491891). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [206795705](https:\/\/api.semanticscholar.org\/CorpusID:206795705). \"Man kann auch ganz burleske Fälle konstruieren. Eine Katze wird in eine Stahlkammer gesperrt, zusammen mit folgender Höllenmaschine (die man gegen den direkten Zugriff der Katze sichern muß): in einem Geigerschen Zählrohr befindet sich eine winzige Menge radioaktiver Substanz, so wenig, daß im Laufe einer Stunde vielleicht eines von den Atomen zerfällt, ebenso wahrscheinlich aber auch keines; geschieht es, so spricht das Zählrohr an und betätigt über ein Relais ein Hämmerchen, das ein Kölbchen mit Blausäure zertrümmert. Hat man dieses ganze System eine Stunde lang sich selbst überlassen, so wird man sich sagen, daß die Katze noch lebt, wenn inzwischen kein Atom zerfallen ist. Der erste Atomzerfall würde sie vergiftet haben. Die Psi-Funktion des ganzen Systems würde das so zum Ausdruck bringen, daß in ihr die lebende und die tote Katze (s.v.v.) \\[sit venia verbo\\] zu gleichen Teilen gemischt oder verschmiert sind. Das Typische an solchen Fällen ist, daß eine ursprünglich auf den Atombereich beschränkte Unbestimmtheit sich in grobsinnliche Unbestimmtheit umsetzt, die sich dann durch direkte Beobachtung entscheiden läßt. Das hindert uns, in so naiver Weise ein \"verwaschenes Modell\" als Abbild der Wirklichkeit gelten zu lassen. An sich enthielte es nichts Unklares oder Widerspruchsvolles. Es ist ein Unterschied zwischen einer verwackelten oder unscharf eingestellten Photographie und einer Aufnahme von Wolken und Nebelschwaden.\"\n2. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Fine_2-0)**\n   [Fine, Arthur](https:\/\/en.wikipedia.org\/wiki\/Arthur_Fine \"Arthur Fine\"). [\"The Einstein-Podolsky-Rosen Argument in Quantum Theory\"](https:\/\/plato.stanford.edu\/entries\/qt-epr\/). *Stanford Encyclopedia of Philosophy*. Retrieved June 11, 2020.\n3. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-3)**\n   [Ball, Philip](https:\/\/en.wikipedia.org\/wiki\/Philip_Ball \"Philip Ball\") (June 25, 2018). [\"Real-Life Schrödinger's Cats Probe the Boundary of the Quantum World\"](https:\/\/web.archive.org\/web\/20250228155932\/https:\/\/www.quantamagazine.org\/real-life-schrodingers-cats-probe-the-boundary-of-the-quantum-world-20180625\/). *Quanta Magazine*. Archived from [the original](https:\/\/www.quantamagazine.org\/real-life-schrodingers-cats-probe-the-boundary-of-the-quantum-world-20180625\/) on February 28, 2025. Retrieved February 24, 2025.\n4. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-4)**\n   Einstein, A.; Podolsky, B.; Rosen, N. (May 15, 1935). \"Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?\". *Physical Review*. **47** (10): 777–780\\. [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/PhysRev.47.777](https:\/\/doi.org\/10.1103%2FPhysRev.47.777). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0031-899X](https:\/\/search.worldcat.org\/issn\/0031-899X).\n5. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-1) [***c***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-2)\n   Fine, Arthur (2017). [\"The Einstein-Podolsky-Rosen Argument in Quantum Theory\"](https:\/\/plato.stanford.edu\/entries\/qt-epr\/). *Stanford Encyclopedia of Philosophy*. Stanford University. Retrieved April 11, 2021.\n6. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-1) [***c***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-2) [***d***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-3) [***e***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-4)\n   Baggott, J. E. (2013). *The quantum story: a history in 40 moments* (Impression: 3 ed.). Oxford: Oxford Univ. Press. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n   \n   [978-0-19-965597-7](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-0-19-965597-7 \"Special:BookSources\/978-0-19-965597-7\")\n   \n   .\n7. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Polkinghorne_7-0)**\n   Polkinghorne, J. C. (1985). [*The Quantum World*](https:\/\/books.google.com\/books?id=lp4JPYnLrtEC&q=%22schrodinger%27s+cat%22+%22alive+dead&pg=PA67). [Princeton University Press](https:\/\/en.wikipedia.org\/wiki\/Princeton_University_Press \"Princeton University Press\"). p. 67. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n   \n   [0-691-02388-3](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/0-691-02388-3 \"Special:BookSources\/0-691-02388-3\")\n   \n   . [Archived](https:\/\/web.archive.org\/web\/20150519001623\/https:\/\/books.google.com\/books?id=lp4JPYnLrtEC&pg=PA67&dq=%22schrodinger%27s+cat%22+%22alive+dead) from the original on May 19, 2015. Retrieved November 20, 2020.\n8. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Tetlow_8-0)**\n   Tetlow, Philip (2012). [*Understanding Information and Computation: From Einstein to Web Science*](https:\/\/books.google.com\/books?id=Rk7O3EG0Xn4C&q=%22alive+and+dead%22&pg=PA321). Gower Publishing, Ltd. p. 321. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n   \n   [978-1-4094-4040-6](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-4094-4040-6 \"Special:BookSources\/978-1-4094-4040-6\")\n   \n   . [Archived](https:\/\/web.archive.org\/web\/20150519001741\/https:\/\/books.google.com\/books?id=Rk7O3EG0Xn4C&pg=PA321&dq=%22alive+and+dead%22) from the original on May 19, 2015.\n9. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-9)**\n   Lazarou, Dimitris (2007). \"Interpretation of quantum theory - An overview\". [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[0712\\.3466](https:\/\/arxiv.org\/abs\/0712.3466) \\[[quant-ph](https:\/\/arxiv.org\/archive\/quant-ph)\\].\n10. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-10)**\n    Trimmer, John D. (1980). \"The Present Situation in Quantum Mechanics: A Translation of Schrödinger's \"Cat Paradox\" Paper\". *Proceedings of the American Philosophical Society*. **124** (5): 323–338\\. [JSTOR](https:\/\/en.wikipedia.org\/wiki\/JSTOR_\\(identifier\\) \"JSTOR (identifier)\") [986572](https:\/\/www.jstor.org\/stable\/986572).\n    \n    The English translation here is based on the German original, not on the inaccurate version in this source's translation of the entire article: [Schrödinger: \"The Present Situation in Quantum Mechanics.\" 5. Are the Variables Really Blurred?](http:\/\/web.archive.org\/web\/20161020061333\/https:\/\/www.tuhh.de\/rzt\/rzt\/it\/QM\/cat.html)\n11. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-11)**\n    Maxwell, Nicholas (January 1, 1993). \"Induction and Scientific Realism: Einstein versus van Fraassen Part Three: Einstein, Aim-Oriented Empiricism and the Discovery of Special and General Relativity\". *The British Journal for the Philosophy of Science*. **44** (2): 275–305\\. [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1093\/bjps\/44.2.275](https:\/\/doi.org\/10.1093%2Fbjps%2F44.2.275). [JSTOR](https:\/\/en.wikipedia.org\/wiki\/JSTOR_\\(identifier\\) \"JSTOR (identifier)\") [687649](https:\/\/www.jstor.org\/stable\/687649).\n12. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-PeresCat_12-0)**\n    [Peres, Asher](https:\/\/en.wikipedia.org\/wiki\/Asher_Peres \"Asher Peres\") (January 1988). [\"Schrödinger's immortal cat\"](http:\/\/link.springer.com\/10.1007\/BF01882873). *Foundations of Physics*. **18** (1): 57–76\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1988FoPh...18...57P](https:\/\/ui.adsabs.harvard.edu\/abs\/1988FoPh...18...57P). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1007\/BF01882873](https:\/\/doi.org\/10.1007%2FBF01882873). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0015-9018](https:\/\/search.worldcat.org\/issn\/0015-9018).\n13. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-SchlosshauerDecoherenceReview_13-0)**\n    Schlosshauer, Maximilian (February 23, 2005). [\"Decoherence, the measurement problem, and interpretations of quantum mechanics\"](https:\/\/link.aps.org\/doi\/10.1103\/RevModPhys.76.1267). *Reviews of Modern Physics*. **76** (4): 1267–1305\\. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[quant-ph\/0312059](https:\/\/arxiv.org\/abs\/quant-ph\/0312059). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2004RvMP...76.1267S](https:\/\/ui.adsabs.harvard.edu\/abs\/2004RvMP...76.1267S). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/RevModPhys.76.1267](https:\/\/doi.org\/10.1103%2FRevModPhys.76.1267).\n14. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Wimmel1992_14-0)**\n    Wimmel, Hermann (1992). [*Quantum physics & observed reality: a critical interpretation of quantum mechanics*](https:\/\/books.google.com\/books?id=-4sJ_fgyZJEC&pg=PA2). World Scientific. p. 2. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-981-02-1010-6](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-981-02-1010-6 \"Special:BookSources\/978-981-02-1010-6\")\n    \n    . [Archived](https:\/\/web.archive.org\/web\/20130520185205\/http:\/\/books.google.com\/books?id=-4sJ_fgyZJEC&pg=PA2) from the original on May 20, 2013. Retrieved May 9, 2011.\n15. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Tales_of_the_Quantum_15-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Tales_of_the_Quantum_15-1)\n    Hobson, Art (2017). [*Tales of the Quantum: Understanding Physics' Most Fundamental Theory*](https:\/\/books.google.com\/books?id=mGduDQAAQBAJ). New York, NY: Oxford University Press. pp. 200–202\\. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-0-19-067963-7](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-0-19-067963-7 \"Special:BookSources\/978-0-19-067963-7\")\n    \n    . Retrieved April 8, 2022.\n16. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-16)**\n    [Omnès, Roland](https:\/\/en.wikipedia.org\/wiki\/Roland_Omn%C3%A8s \"Roland Omnès\") (1999). [*Understanding Quantum Mechanics*](https:\/\/books.google.com\/books?id=XET_DwAAQBAJ). Princeton, New Jersey: Princeton University Press. pp. 60–62\\. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [0-691-00435-8](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/0-691-00435-8 \"Special:BookSources\/0-691-00435-8\")\n    \n    . Retrieved April 8, 2022.\n17. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Surfing_the_Quantum_World_17-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Surfing_the_Quantum_World_17-1)\n    Levin, Frank S. (2017). [*Surfing the Quantum World*](https:\/\/books.google.com\/books?id=Y1w-DwAAQBAJ). New York, NY: Oxford University Press. pp. 229–232\\. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-0-19-880827-5](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-0-19-880827-5 \"Special:BookSources\/978-0-19-880827-5\")\n    \n    . Retrieved April 8, 2022.\n18. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-18)**\n    Puri, Ravinder R. (2017). [*Non-Relativistic Quantum Mechanics*](https:\/\/books.google.com\/books?id=qDbSDgAAQBAJ). Cambridge, United Kingdom: Cambridge University Press. p. 146. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-1-107-16436-9](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-107-16436-9 \"Special:BookSources\/978-1-107-16436-9\")\n    \n    . Retrieved April 8, 2022.\n19. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Carpenter2006_19-0)**\n    Carpenter RHS; Anderson AJ (2006). [\"The death of Schrödinger's cat and of consciousness-based wave-function collapse\"](https:\/\/web.archive.org\/web\/20061130173850\/http:\/\/www.ensmp.fr\/aflb\/AFLB-311\/aflb311m387.pdf) (PDF). *[Annales de la Fondation Louis de Broglie](https:\/\/en.wikipedia.org\/wiki\/Annales_de_la_Fondation_Louis_de_Broglie \"Annales de la Fondation Louis de Broglie\")*. **31** (1): 45–52\\. Archived from [the original](http:\/\/www.ensmp.fr\/aflb\/AFLB-311\/aflb311m387.pdf) (PDF) on November 30, 2006. Retrieved September 10, 2010.\n20. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Okon2006_20-0)**\n    Okón E, Sebastián MA (2016). \"How to Back up or Refute Quantum Theories of Consciousness\". *Mind and Matter*. **14** (1): 25–49\\.\n21. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Faye2008_21-0)**\n    [Faye, J](https:\/\/en.wikipedia.org\/wiki\/Jan_Faye \"Jan Faye\") (January 24, 2008). [\"Copenhagen Interpretation of Quantum Mechanics\"](http:\/\/plato.stanford.edu\/entries\/qm-copenhagen\/). *[Stanford Encyclopedia of Philosophy](https:\/\/en.wikipedia.org\/wiki\/Stanford_Encyclopedia_of_Philosophy \"Stanford Encyclopedia of Philosophy\")*. The Metaphysics Research Lab Center for the Study of Language and Information, [Stanford University](https:\/\/en.wikipedia.org\/wiki\/Stanford_University \"Stanford University\"). Retrieved September 19, 2010.\n22. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-22)**\n    [John Bell](https:\/\/en.wikipedia.org\/wiki\/John_Stewart_Bell \"John Stewart Bell\") (1990). \"Against 'measurement'\". *Physics World*. **3** (8): 33–41\\. [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1088\/2058-7058\/3\/8\/26](https:\/\/doi.org\/10.1088%2F2058-7058%2F3%2F8%2F26).\n23. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-23)**\n    [Niels Bohr](https:\/\/en.wikipedia.org\/wiki\/Niels_Bohr \"Niels Bohr\") (1985) \\[May 16, 1947\\]. Jørgen Kalckar (ed.). [*Foundations of Quantum Physics I (1926-1932)*](https:\/\/www.nbarchive.dk\/publications\/bcw\/). Niels Bohr: Collected Works. Vol. 6. pp. 451–454\\.\n24. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-24)**\n    Stig Stenholm (1983). \"To fathom space and time\". In [Pierre Meystre](https:\/\/en.wikipedia.org\/w\/index.php?title=Pierre_Meystre&action=edit&redlink=1 \"Pierre Meystre (page does not exist)\") (ed.). *Quantum Optics, Experimental Gravitation, and Measurement Theory*. Plenum Press. p. 121. \"The role of irreversibility in the theory of measurement has been emphasized by many. Only this way can a permanent record be obtained. The fact that separate pointer positions must be of the asymptotic nature usually associated with irreversibility has been utilized in the measurement theory of Daneri, Loinger and Prosperi (1962). It has been accepted as a formal representation of Bohr's ideas by Rosenfeld (1966).\"\n25. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-25)**\n    Haake, Fritz (April 1, 1993). \"Classical motion of meter variables in the quantum theory of measurement\". *[Physical Review A](https:\/\/en.wikipedia.org\/wiki\/Physical_Review_A \"Physical Review A\")*. **47** (4): 2506–2517\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1993PhRvA..47.2506H](https:\/\/ui.adsabs.harvard.edu\/abs\/1993PhRvA..47.2506H). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/PhysRevA.47.2506](https:\/\/doi.org\/10.1103%2FPhysRevA.47.2506). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [9909217](https:\/\/pubmed.ncbi.nlm.nih.gov\/9909217).\n26. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-zurek03_26-0)**\n    [Zurek, Wojciech H.](https:\/\/en.wikipedia.org\/wiki\/Wojciech_H._Zurek \"Wojciech H. Zurek\") (2003). \"Decoherence, einselection, and the quantum origins of the classical\". *Reviews of Modern Physics*. **75** (3): 715. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[quant-ph\/0105127](https:\/\/arxiv.org\/abs\/quant-ph\/0105127). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2003RvMP...75..715Z](https:\/\/ui.adsabs.harvard.edu\/abs\/2003RvMP...75..715Z). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/revmodphys.75.715](https:\/\/doi.org\/10.1103%2Frevmodphys.75.715). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [14759237](https:\/\/api.semanticscholar.org\/CorpusID:14759237).\n27. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-zurek91_27-0)** [Wojciech H. Zurek](https:\/\/en.wikipedia.org\/wiki\/Wojciech_H._Zurek \"Wojciech H. Zurek\"), \"Decoherence and the transition from quantum to classical\", *Physics Today*, 44, pp. 36–44 (1991)\n28. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-28)**\n    Home, D.; Whitaker, M. A. B. (1992). \"Ensemble Interpretations of Quantum Mechanics: A Modern Perspective\". *Physics Reports*. **210** (4): 223–317\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1992PhR...210..223H](https:\/\/ui.adsabs.harvard.edu\/abs\/1992PhR...210..223H). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1016\/0370-1573(92)90088-H](https:\/\/doi.org\/10.1016%2F0370-1573%2892%2990088-H).\n29. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-29)**\n    [Rovelli, Carlo](https:\/\/en.wikipedia.org\/wiki\/Carlo_Rovelli \"Carlo Rovelli\") (1996). \"Relational Quantum Mechanics\". *International Journal of Theoretical Physics*. **35** (8): 1637–1678\\. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[quant-ph\/9609002](https:\/\/arxiv.org\/abs\/quant-ph\/9609002). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1996IJTP...35.1637R](https:\/\/ui.adsabs.harvard.edu\/abs\/1996IJTP...35.1637R). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1007\/BF02302261](https:\/\/doi.org\/10.1007%2FBF02302261). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [16325959](https:\/\/api.semanticscholar.org\/CorpusID:16325959).\n30. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-30)**\n    Cramer, John G. (July 1986). [\"The transactional interpretation of quantum mechanics\"](https:\/\/www.researchgate.net\/publication\/280926546). *Reviews of Modern Physics*. **58** (3): 647–685\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1986RvMP...58..647C](https:\/\/ui.adsabs.harvard.edu\/abs\/1986RvMP...58..647C). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/RevModPhys.58.647](https:\/\/doi.org\/10.1103%2FRevModPhys.58.647).\n31. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-31)**\n    Okon, Elias; Sudarsky, Daniel (February 1, 2014). \"Benefits of Objective Collapse Models for Cosmology and Quantum Gravity\". *Foundations of Physics*. **44** (2): 114–143\\. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[1309\\.1730](https:\/\/arxiv.org\/abs\/1309.1730). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2014FoPh...44..114O](https:\/\/ui.adsabs.harvard.edu\/abs\/2014FoPh...44..114O). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1007\/s10701-014-9772-6](https:\/\/doi.org\/10.1007%2Fs10701-014-9772-6). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [1572-9516](https:\/\/search.worldcat.org\/issn\/1572-9516). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [67831520](https:\/\/api.semanticscholar.org\/CorpusID:67831520).\n32. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-32)**\n    Khazali, Mohammadsadegh; Lau, Hon Wai; Humeniuk, Adam; Simon, Christoph (August 11, 2016). \"Large energy superpositions via Rydberg dressing\". *Physical Review A*. **94** (2) 023408. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[1509\\.01303](https:\/\/arxiv.org\/abs\/1509.01303). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2016PhRvA..94b3408K](https:\/\/ui.adsabs.harvard.edu\/abs\/2016PhRvA..94b3408K). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/physreva.94.023408](https:\/\/doi.org\/10.1103%2Fphysreva.94.023408). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [2469-9926](https:\/\/search.worldcat.org\/issn\/2469-9926). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [118364289](https:\/\/api.semanticscholar.org\/CorpusID:118364289).\n33. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-33)**\n    [\"What is the world's biggest Schrodinger cat?\"](http:\/\/physics.stackexchange.com\/questions\/3309\/what-is-the-worlds-biggest-schrodinger-cat). *stackexchange.com*. [Archived](https:\/\/web.archive.org\/web\/20120108000629\/http:\/\/physics.stackexchange.com\/questions\/3309\/what-is-the-worlds-biggest-schrodinger-cat) from the original on January 8, 2012.\n34. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-34)**\n    [\"NIST Researchers Create 'Quantum Cats' Made of Light\"](https:\/\/web.archive.org\/web\/20170507224218\/https:\/\/www.nist.gov\/news-events\/news\/2010\/08\/nist-researchers-create-quantum-cats-made-light). *NIST*. August 31, 2010. Archived from [the original](https:\/\/www.nist.gov\/news-events\/news\/2010\/08\/nist-researchers-create-quantum-cats-made-light) on May 7, 2017.\n35. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-35)**\n    Sychev, Demid V.; Ulanov, Alexander E.; Pushkina, Anastasia A.; Richards, Matthew W.; Fedorov, Ilya A.; Lvovsky, Alexander I. (June 2017). [\"Enlargement of optical Schrödinger's cat states\"](https:\/\/www.nature.com\/articles\/nphoton.2017.57). *Nature Photonics*. **11** (6): 379–382\\. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[1609\\.08425](https:\/\/arxiv.org\/abs\/1609.08425). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2017NaPho..11..379S](https:\/\/ui.adsabs.harvard.edu\/abs\/2017NaPho..11..379S). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1038\/nphoton.2017.57](https:\/\/doi.org\/10.1038%2Fnphoton.2017.57). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [1749-4885](https:\/\/search.worldcat.org\/issn\/1749-4885).\n36. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-36)**\n    Monroe, C.; Meekhof, D. M.; King, B. E.; Wineland, D. J. (May 24, 1996). \"A \"Schrödinger's cat\" Superposition State of an Atom\". *Science*. **272** (5265): 1131–1136\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1996Sci...272.1131M](https:\/\/ui.adsabs.harvard.edu\/abs\/1996Sci...272.1131M). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1126\/science.272.5265.1131](https:\/\/doi.org\/10.1126%2Fscience.272.5265.1131). [PMID](https:\/\/en.wikipedia.org\/wiki\/PMID_\\(identifier\\) \"PMID (identifier)\") [8662445](https:\/\/pubmed.ncbi.nlm.nih.gov\/8662445). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [2311821](https:\/\/api.semanticscholar.org\/CorpusID:2311821).\n37. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-37)**\n    [\"Physics World: *Schrödinger's cat comes into view*\"](https:\/\/physicsworld.com\/a\/schrodingers-cat-comes-into-view\/). July 5, 2000.\n38. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-38)**\n    Castelvecchi, Davide. [\"Macro-Weirdness: \"Quantum Microphone\" Puts Naked-Eye Object in 2 Places at Once\"](https:\/\/web.archive.org\/web\/20120319021316\/http:\/\/www.scientificamerican.com\/article.cfm?id=quantum-microphone). *Scientific American*. Archived from [the original](https:\/\/www.scientificamerican.com\/article\/quantum-microphone\/) on March 19, 2012.\n39. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-39)**\n    Romero-Isart, O.; Juan, M. L.; Quidant, R.; Cirac, J. I. (2010). \"Toward Quantum Superposition of Living Organisms\". *New Journal of Physics*. **12** (3) 033015. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[0909\\.1469](https:\/\/arxiv.org\/abs\/0909.1469). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2010NJPh...12c3015R](https:\/\/ui.adsabs.harvard.edu\/abs\/2010NJPh...12c3015R). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1088\/1367-2630\/12\/3\/033015](https:\/\/doi.org\/10.1088%2F1367-2630%2F12%2F3%2F033015). [S2CID](https:\/\/en.wikipedia.org\/wiki\/S2CID_\\(identifier\\) \"S2CID (identifier)\") [59151724](https:\/\/api.semanticscholar.org\/CorpusID:59151724).\n40. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-40)**\n    [\"Could 'Schrödinger's bacterium' be placed in a quantum superposition?\"](http:\/\/physicsworld.com\/cws\/article\/news\/2015\/sep\/21\/could-schrodingers-bacterium-be-placed-in-a-quantum-superposition). *physicsworld.com*. [Archived](https:\/\/web.archive.org\/web\/20160730174613\/http:\/\/physicsworld.com\/cws\/article\/news\/2015\/sep\/21\/could-schrodingers-bacterium-be-placed-in-a-quantum-superposition) from the original on July 30, 2016.\n41. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-LS-20191107_41-0)**\n    Najjar, Dana (November 7, 2019). [\"Physicists Can Finally Peek at Schrödinger's Cat Without Killing It Forever\"](https:\/\/www.livescience.com\/schrodingers-cat-can-be-peeked-at.html). *[Live Science](https:\/\/en.wikipedia.org\/wiki\/Live_Science \"Live Science\")*. Retrieved November 7, 2019.\n42. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-NJP-20191001_42-0)**\n    Patekar, Kartik; Hofmann, Holger F. (2019). [\"The role of system–meter entanglement in controlling the resolution and decoherence of quantum measurements\"](https:\/\/doi.org\/10.1088%2F1367-2630%2Fab4451). *[New Journal of Physics](https:\/\/en.wikipedia.org\/wiki\/New_Journal_of_Physics \"New Journal of Physics\")*. **21** (10): 103006. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[1905\\.09978](https:\/\/arxiv.org\/abs\/1905.09978). [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2019NJPh...21j3006P](https:\/\/ui.adsabs.harvard.edu\/abs\/2019NJPh...21j3006P). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1088\/1367-2630\/ab4451](https:\/\/doi.org\/10.1088%2F1367-2630%2Fab4451).\n43. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-43)**\n    Crease, Robert P. (May 27, 2024). [\"Ursula Le Guin: the pioneering author we should thank for popularizing Schrödinger's cat\"](https:\/\/physicsworld.com\/a\/ursula-le-guin-the-pioneering-author-we-should-thank-for-popularizing-schrodingers-cat\/). *Physics World*. Retrieved October 27, 2024.\n44. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-100CCC_44-0)**\n    Sam Stall (May 1, 2007). [*100 Cats Who Changed Civilization*](https:\/\/books.google.com\/books?id=coXIF8WbEKEC). Quirk Books. p. 34. [ISBN](https:\/\/en.wikipedia.org\/wiki\/ISBN_\\(identifier\\) \"ISBN (identifier)\")\n    \n    [978-1-59474-163-0](https:\/\/en.wikipedia.org\/wiki\/Special:BookSources\/978-1-59474-163-0 \"Special:BookSources\/978-1-59474-163-0\")\n    \n    .\n45. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Crease_45-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Crease_45-1)\n    Crease, Robert P. (2012). [\"The cat that never dies\"](https:\/\/doi.org\/10.1088%2F2058-7058%2F25%2F04%2F27). *Physics World*. **25** (4): 18–19\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2012PhyW...25d..18C](https:\/\/ui.adsabs.harvard.edu\/abs\/2012PhyW...25d..18C). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1088\/2058-7058\/25\/04\/27](https:\/\/doi.org\/10.1088%2F2058-7058%2F25%2F04%2F27).\n46. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-46)**\n    Ryan, Marie-Laure (2011). [\"Narrative\/Science Entanglements: On the Thousand and One Literary Lives of Schrödinger's Cat\"](https:\/\/www.jstor.org\/stable\/41289295). *Narrative*. **19** (2): 171–186\\. [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [1063-3685](https:\/\/search.worldcat.org\/issn\/1063-3685). [JSTOR](https:\/\/en.wikipedia.org\/wiki\/JSTOR_\\(identifier\\) \"JSTOR (identifier)\") [41289295](https:\/\/www.jstor.org\/stable\/41289295).\n47. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-47)**\n    Kravitz, Bennett (2013). [\"Thoughts on the Anti-Detective in Paul Auster's \"New York Trilogy\", Adam Ross's \"Mister Peanut\", and Martha Grimes' \"The Old Wine Shades\"\"](https:\/\/www.jstor.org\/stable\/23610151). *Studies in Popular Culture*. **36** (1): 45–61\\. [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0888-5753](https:\/\/search.worldcat.org\/issn\/0888-5753). [JSTOR](https:\/\/en.wikipedia.org\/wiki\/JSTOR_\\(identifier\\) \"JSTOR (identifier)\") [23610151](https:\/\/www.jstor.org\/stable\/23610151).\n48. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-48)**\n    Branzburg, Judith V. (October 31, 2000). [\"Dead cats and live bodies\"](https:\/\/www.proquest.com\/openview\/a751e740ad411cd002452117c93b4322). *The Lesbian Review of Books*. **7** (1): 3.\n49. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-49)**\n    [\"SFE: Wilson, Robert Anton\"](https:\/\/sf-encyclopedia.com\/entry\/wilson_robert_anton). *sf-encyclopedia.com*. Retrieved December 3, 2022.\n50. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-50)**\n    [\"SFE: Thought Experiment\"](https:\/\/sf-encyclopedia.com\/entry\/thought_experiment). *sf-encyclopedia.com*. Retrieved December 3, 2022.\n51. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-51)**\n    Goldberg, Matt (April 17, 2020). [\"A Serious Man Ending Explained: The Crucible of American Judaism\"](https:\/\/collider.com\/a-serious-man-ending-explained-american-judaism\/). *Collider*. Retrieved December 3, 2022.\n52. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-52)**\n    Orr, Christopher (September 25, 2014). [\"30 Years of Coens: A Serious Man\"](https:\/\/web.archive.org\/web\/20221203220152\/https:\/\/www.theatlantic.com\/entertainment\/archive\/2014\/09\/30-years-of-coens-a-serious-man\/380732\/). *[The Atlantic](https:\/\/en.wikipedia.org\/wiki\/The_Atlantic \"The Atlantic\")*. Archived from [the original](https:\/\/www.theatlantic.com\/entertainment\/archive\/2014\/09\/30-years-of-coens-a-serious-man\/380732\/) on December 3, 2022. Retrieved December 3, 2022.\n53. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-53)**\n    [Ebert, Roger](https:\/\/en.wikipedia.org\/wiki\/Roger_Ebert \"Roger Ebert\") (March 4, 2013). [\"The Coen Brothers and Serious Quantum Theory\"](https:\/\/web.archive.org\/web\/20201029024134\/https:\/\/www.rogerebert.com\/roger-ebert\/the-coen-brothers-and-serious-quantum-theory). *[Chicago Sun Times](https:\/\/en.wikipedia.org\/wiki\/Chicago_Sun_Times \"Chicago Sun Times\")*. Archived from [the original](https:\/\/www.rogerebert.com\/roger-ebert\/the-coen-brothers-and-serious-quantum-theory) on October 29, 2020.\n54. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-54)**\n    Collis, Clark (June 20, 2014). [\"Coherence\"](https:\/\/web.archive.org\/web\/20221203220151\/https:\/\/ew.com\/article\/2014\/06\/20\/coherence\/). *Entertainment Weekly*. Archived from [the original](https:\/\/ew.com\/article\/2014\/06\/20\/coherence\/) on December 3, 2022. Retrieved December 3, 2022.\n55. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-55)**\n    Landsman, Peggy (April 1, 2022). [\"\"Schrodinger's Cat\"\"](https:\/\/web.archive.org\/web\/20220529020959\/https:\/\/www.scientificamerican.com\/article\/poem-schroedingers-cat\/). *Scientific American*. Archived from [the original](https:\/\/www.scientificamerican.com\/article\/poem-schroedingers-cat\/) on May 29, 2022. Retrieved February 22, 2023.\n56. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-56)**\n    Robbins, Hollis. [\"\"His Paws Upon The Dish\"\"](http:\/\/www.percontra.net\/issues\/34\/poetry\/his-paws-upon-the\/). *Per Contra Journal*. Per Contra. Retrieved February 22, 2023.\n57. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger's_Girlfriend_57-0)**\n    Ehren, Christine (November 18, 2001). [\"World Premiere Schrodinger's Girlfriend Closes Nov. 18 at San Fran's Magic\"](https:\/\/web.archive.org\/web\/20100517085507\/http:\/\/www.playbill.com\/news\/article\/63363-World-Premiere-Schrodingers-Girlfriend-Closes-Nov-18-at-San-Frans-Magic). *Schrodingers Girlfriend*. Playbill Review. Archived from [the original](http:\/\/www.playbill.com\/news\/article\/63363-World-Premiere-Schrodingers-Girlfriend-Closes-Nov-18-at-San-Frans-Magic) on May 17, 2010. Retrieved January 6, 2015.\n58. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodingers_Girlfriend_SFG_58-0)**\n    Hurwitt, Robert (November 5, 2001). [\"'Girlfriend' runs out of inspiration \/ Ideas bog down physics comedy\"](https:\/\/web.archive.org\/web\/20151126043542\/http:\/\/www.sfgate.com\/entertainment\/article\/Girlfriend-runs-out-of-inspiration-Ideas-bog-2862061.php). *SFGate Review*. Archived from [the original](http:\/\/www.sfgate.com\/entertainment\/article\/Girlfriend-runs-out-of-inspiration-Ideas-bog-2862061.php) on November 26, 2015. Retrieved December 5, 2015.\n59. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-59)**\n    Mohan, Geoffrey (August 12, 2013). [\"Google doodle honors physicist Erwin Schrodinger and his cat\"](https:\/\/web.archive.org\/web\/20221202232119\/https:\/\/www.baltimoresun.com\/la-sci-sn-schrodinger-cat-20130812-story.html). *Baltimore Sun*. Archived from [the original](https:\/\/www.baltimoresun.com\/la-sci-sn-schrodinger-cat-20130812-story.html) on December 2, 2022. Retrieved December 2, 2022.\n60. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-The_Age_60-0)**\n    Farrer, Gordon (January 6, 2006). [\"Sum thing to do with maths genius\"](https:\/\/web.archive.org\/web\/20080115093824\/http:\/\/www.theage.com.au\/news\/tv--radio\/sum-thing-to-do-with-maths-genius\/2006\/01\/05\/1136387564868.html). *The Age*. Melbourne. Archived from [the original](http:\/\/www.theage.com.au\/news\/tv--radio\/sum-thing-to-do-with-maths-genius\/2006\/01\/05\/1136387564868.html) on January 15, 2008. Retrieved August 28, 2007.\n61. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-61)**\n    [Singh, Simon](https:\/\/en.wikipedia.org\/wiki\/Simon_Singh \"Simon Singh\") (October 2014). [\"Theories of quantum levity\"](https:\/\/iopscience.iop.org\/article\/10.1088\/2058-7058\/27\/10\/41). *Physics World*. **27** (10): 80. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[2014PhyW...27j..80S](https:\/\/ui.adsabs.harvard.edu\/abs\/2014PhyW...27j..80S). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1088\/2058-7058\/27\/10\/41](https:\/\/doi.org\/10.1088%2F2058-7058%2F27%2F10%2F41). [ISSN](https:\/\/en.wikipedia.org\/wiki\/ISSN_\\(identifier\\) \"ISSN (identifier)\") [0953-8585](https:\/\/search.worldcat.org\/issn\/0953-8585).\n62. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-62)**\n    [\"The Famous Schrodinger's Cat Thought Experiment Gets Brought to Life in an Off-Kilter Animation\"](https:\/\/web.archive.org\/web\/20221202230558\/https:\/\/www.openculture.com\/2017\/03\/the-famous-schrodingers-cat-thought-experiment-gets-brought-to-life-in-an-off-kilter-animation.html). *Open Culture*. March 24, 2017. Archived from [the original](https:\/\/www.openculture.com\/2017\/03\/the-famous-schrodingers-cat-thought-experiment-gets-brought-to-life-in-an-off-kilter-animation.html) on December 2, 2022. Retrieved December 2, 2022.\n63. **[^](https:\/\/en.wikipedia.org\/wiki\/Schr%C3%B6dinger%27s_cat#cite_ref-63)**\n    [\"NIGHTMARE シュレーディンガーナイフ 歌詞 – 歌詞探索【歌詞リリ】\"](https:\/\/web.archive.org\/web\/20230528210243\/https:\/\/www.lyrical-nonsense.com\/lyrics\/nightmare\/shrodinger-knife\/). *Lyrical Nonsense*. Archived from [the original](https:\/\/www.lyrical-nonsense.com\/lyrics\/nightmare\/shrodinger-knife\/) on May 28, 2023. Retrieved May 28, 2023.\n\nFurther reading\n\n- [Einstein, Albert](https:\/\/en.wikipedia.org\/wiki\/Albert_Einstein \"Albert Einstein\"); [Podolsky, Boris](https:\/\/en.wikipedia.org\/wiki\/Boris_Podolsky \"Boris Podolsky\"); [Rosen, Nathan](https:\/\/en.wikipedia.org\/wiki\/Nathan_Rosen \"Nathan Rosen\") (May 15, 1935). [\"Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?\"](https:\/\/doi.org\/10.1103%2FPhysRev.47.777). *Physical Review*. **47** (10): 777–780\\. [Bibcode](https:\/\/en.wikipedia.org\/wiki\/Bibcode_\\(identifier\\) \"Bibcode (identifier)\"):[1935PhRv...47..777E](https:\/\/ui.adsabs.harvard.edu\/abs\/1935PhRv...47..777E). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1103\/PhysRev.47.777](https:\/\/doi.org\/10.1103%2FPhysRev.47.777).\n- Leggett, Tony (August 2000). [\"New Life for Schrödinger's Cat\"](https:\/\/jrfriedman.people.amherst.edu\/Leggett%20Physics%20World%20article\/PW%20article.pdf) (PDF). Physics World. pp. 23–24. Retrieved February 28, 2020.\n  An article on experiments with \"cat state\" superpositions in superconducting rings, in which the electrons go around the ring in two directions simultaneously.\n- Trimmer, John D. (1980). \"The Present Situation in Quantum Mechanics: A Translation of Schrödinger's \"Cat Paradox\" Paper\". *[Proceedings of the American Philosophical Society](https:\/\/en.wikipedia.org\/wiki\/Proceedings_of_the_American_Philosophical_Society \"Proceedings of the American Philosophical Society\")*. **124** (5): 323–338\\. [JSTOR](https:\/\/en.wikipedia.org\/wiki\/JSTOR_\\(identifier\\) \"JSTOR (identifier)\") [986572](https:\/\/www.jstor.org\/stable\/986572).\n  ([registration required](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Verifiability#Access_to_sources \"Wikipedia:Verifiability\"))\n- Yam, Phillip (October 9, 2012). [\"Bringing Schrödinger's Cat to Life\"](https:\/\/www.scientificamerican.com\/article\/bringing-schrodingers-quantum-cat-to-life\/). *Scientific American*. Retrieved February 28, 2020.\n  A description of investigations of quantum \"cat states\" and wave function collapse by [Serge Haroche](https:\/\/en.wikipedia.org\/wiki\/Serge_Haroche \"Serge Haroche\") and [David J. Wineland](https:\/\/en.wikipedia.org\/wiki\/David_J._Wineland \"David J. Wineland\"), for which they won the 2012 [Nobel Prize in Physics](https:\/\/en.wikipedia.org\/wiki\/List_of_Nobel_laureates_in_Physics \"List of Nobel laureates in Physics\").\n- Violaris, M. (2023). *A Physics Lab Inside Your Head: Quantum Thought Experiments as an Educational Tool*. 2023 IEEE International Conference on Quantum Computing and Engineering (QCE). Bellevue, WA, USA. pp. 58–67\\. [arXiv](https:\/\/en.wikipedia.org\/wiki\/ArXiv_\\(identifier\\) \"ArXiv (identifier)\"):[2312\\.07840](https:\/\/arxiv.org\/abs\/2312.07840). [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.1109\/QCE57702.2023.20325](https:\/\/doi.org\/10.1109%2FQCE57702.2023.20325).\n  Reduction of the Schrödinger's cat to a simple [quantum circuit](https:\/\/en.wikipedia.org\/wiki\/Quantum_circuit \"Quantum circuit\").\n\nExternal links\n\n- [A spoken word version](https:\/\/en.wikipedia.org\/wiki\/File:Schrodingers-cat.ogg \"File:Schrodingers-cat.ogg\") of this article (created from a revision of the article dated 2013-08-12).\n- *[Schrödinger's Cat](http:\/\/www.informationphilosopher.com\/solutions\/experiments\/schrodingerscat\/)* from the Information Philosopher.\n- [Schrödinger's Cat - Sixty Symbols](http:\/\/www.sixtysymbols.com\/videos\/schrodinger.htm) - a video published by the [University of Nottingham](https:\/\/en.wikipedia.org\/wiki\/University_of_Nottingham \"University of Nottingham\").\n- [Schrödinger's Cat](https:\/\/soundcloud.com\/siftpodcast\/schr-dingers-cat) - a podcast produced by Sift.","meta_canonical":null}

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Boilerpipe Text	Schrödinger's cat: a cat, a flask of poison, and a radioactive source connected to a Geiger counter are placed in a sealed box. As illustrated, the quantum description uses a superposition of an alive cat and one that has died. In quantum mechanics , Schrödinger's cat is a thought experiment concerning quantum superposition . In the thought experiment, a hypothetical cat in a closed box may be considered to be simultaneously both alive and dead while it is unobserved, as a result of its fate being linked to a random subatomic event that may or may not occur. This experiment, viewed this way, is described as a paradox . This thought experiment was devised by physicist Erwin Schrödinger in 1935, [ 1 ] in a discussion with Albert Einstein , [ 2 ] to illustrate what Schrödinger saw as the problems of Niels Bohr and Werner Heisenberg 's philosophical views on quantum mechanics. In Schrödinger's original formulation, a cat, a flask of poison, and a radioactive source are placed in a sealed box. If an internal radiation monitor such as a Geiger counter detects radioactivity (a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. If no decaying atom triggers the monitor, the cat remains alive. Mathematically, the wave function that describes the contents of the box is a combination, or quantum superposition , of these two possibilities. Yet, when one looks in the box, one sees the cat either alive or dead, not both alive and dead. This poses the question of when exactly quantum superposition ends and reality resolves into one possibility or the other. Although originally a critique of Bohr and Heisenberg, Schrödinger's seemingly paradoxical thought experiment became part of the foundation of quantum mechanics. It is often featured in theoretical discussions of the interpretations of quantum mechanics , particularly in situations involving the measurement problem . As a result, Schrödinger's cat has had enduring appeal in popular culture . The experiment is not intended to be actually performed on a cat, but rather as an easily understandable illustration of the behavior of atoms. Experiments at the atomic scale have been carried out, showing that very small objects may exist as superpositions, but superposing an object as large as a cat would pose considerable technical difficulties. [ 3 ] Fundamentally, the Schrödinger's cat experiment asks how long quantum superpositions last and when (or whether) they collapse. Different interpretations of the mathematics of quantum mechanics have been proposed that give different explanations for this process. Origin and motivation Unsolved problem in physics How does the quantum description of reality, which includes elements such as the superposition of states and wavefunction collapse or quantum decoherence, give rise to the reality we perceive? Another way of stating this question regards the measurement problem: What constitutes a "measurement" that apparently causes the wave function to collapse into a definite state? Schrödinger intended his thought experiment as a discussion of the EPR article —named after its authors Einstein , Podolsky , and Rosen —in 1935. [ 4 ] [ 5 ] The EPR article highlighted the counterintuitive nature of quantum superpositions , in which a quantum system for two particles does not separate [ 6 ] : 150 even when the particles are detected far from their last point of contact. The EPR paper concludes with a claim that this lack of separability meant that quantum mechanics as a theory of reality was incomplete. Schrödinger and Einstein exchanged letters about Einstein's EPR article, in the course of which Einstein pointed out that the state of an unstable keg of gunpowder will, after a while, contain a superposition of both exploded and unexploded states. [ 5 ] To further illustrate, Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a closed steel chamber, wherein the cat's life or death depended on the state of a radioactive atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the position taken by Bohr and Heisenberg would be that the cat remains both alive and dead until the state has been observed. Schrödinger did not wish to promote the idea of dead-and-live cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics, [ 1 ] thus employing reductio ad absurdum . Since Schrödinger's time, various interpretations of the mathematics of quantum mechanics have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real, while others do not. [ 7 ] [ 8 ] Intended as a critique of ideas prevalent in 1935, the Schrödinger's cat thought experiment remains a touchstone for modern interpretations of quantum mechanics and can be used to illustrate and compare their strengths and weaknesses. [ 9 ] [ better source needed ] Thought experiment A life-size cat figure in the garden of Huttenstrasse 9, Zurich, where Erwin Schrödinger lived from 1921 to 1926. Depending on the light conditions, the figure appears to be either a live cat or a dead one. Schrödinger wrote: [ 1 ] [ 10 ] One can contrive even completely burlesque [farcical] cases. A cat is put in a steel chamber along with the following infernal device (which must be secured against direct interference by the cat): in a Geiger counter , there is a tiny amount of radioactive substance, so tiny that in the course of an hour one of the atoms will perhaps decay, but also, with equal probability, that none of them will; if it does happen, the counter tube will discharge and through a relay release a hammer that will shatter a small flask of hydrocyanic acid . If one has left this entire system to itself for an hour, one would tell oneself that the cat is still alive if no atom has decayed in the meantime. Even a single atomic decay would have poisoned it. The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or spread out in equal parts. It is typical of these cases that an indeterminacy originally restricted to the atomic domain turns into a sensually observable [macroscopic] indeterminacy, which can then be resolved by direct observation. This prevents us from so naïvely accepting a "blurred model" as representative of reality. Per se, it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks. Schrödinger developed his famous thought experiment in correspondence with Einstein. He suggested this 'quite ridiculous case' to illustrate his conclusion that the wave function cannot represent reality. [ 6 ] : 153 The wave function description of the complete cat system implies that the reality of the cat mixes the living and dead cat. [ 6 ] : 154 Einstein was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote: [ 6 ] : 157 You are the only contemporary physicist, besides Laue , who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gun powder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation. [ 11 ] Note that the charge of gunpowder is not mentioned in Schrödinger's setup, which uses a Geiger counter as an amplifier and hydrocyanic poison instead of gunpowder. The gunpowder had been mentioned in Einstein's original suggestion to Schrödinger 15 years before, and Einstein carried it forward to the present discussion. [ 5 ] Analysis In modern terms Schrödinger's hypothetical cat experiment describes the measurement problem : quantum theory describes the cat system as a combination of two possible outcomes but only one outcome is ever observed. [ 12 ] : 57 [ 13 ] : 1269 The experiment poses the question, " when does a quantum system stop existing as a superposition of states and become one or the other?" (More technically, when does the actual quantum state stop being a non-trivial linear combination of states, each of which resembles different classical states, and instead begin to have a unique classical description?) Standard microscopic quantum mechanics describes multiple possible outcomes of experiments but only one outcome is observed. The thought experiment illustrates this apparent paradox. Our intuition says that the cat cannot be in more than one state simultaneously—yet the quantum mechanical description of the thought experiment requires such a condition. Interpretations Since Schrödinger's time, other interpretations of quantum mechanics have been proposed that give different answers to the questions posed by Schrödinger's cat of how long superpositions last and when (or whether ) they collapse. Copenhagen interpretation A commonly held interpretation of quantum mechanics is the Copenhagen interpretation. [ 14 ] In the Copenhagen interpretation, a measurement results in only one state of a superposition. This thought experiment makes apparent the fact that this interpretation simply provides no explanation for the state of the cat while the box is closed. The wavefunction description of the system consists of a superposition of the states "decayed nucleus/dead cat" and "undecayed nucleus/living cat". Only when the box is opened and observed can we make a statement about the cat. [ 6 ] : 157 Role of consciousness In 1932, John von Neumann described in his book Mathematical Foundations of Quantum Mechanics a pattern where the radioactive source is observed by a device, which itself is observed by another device and so on. It makes no difference in the predictions of quantum theory where along this chain of causal effects the superposition collapses. [ 15 ] This potentially infinite chain could be broken if the last device is replaced by a conscious observer. This solved the problem because it was claimed that an individual's consciousness cannot be multiple. [ 16 ] Eugene Wigner asserted that an observer is necessary for a collapse to one or the other (e.g., either a live cat or a dead cat) of the terms on the right-hand side of a wave function . Wigner discussed the interpretation in a thought experiment known as Wigner's friend . [ 17 ] Wigner supposed that a friend opened the box and observed the cat without telling anyone. From Wigner's conscious perspective, the friend is now part of the wave function and has seen a live cat and seen a dead cat. To a third person's conscious perspective, Wigner himself becomes part of the wave function once Wigner learns the outcome from the friend. This could be extended indefinitely. [ 17 ] A resolution of the paradox is that the triggering of the Geiger counter counts as a measurement of the state of the radioactive substance. Because a measurement has already occurred deciding the state of the cat, the subsequent observation by a human records only what has already occurred. [ 18 ] Analysis of an actual experiment by Roger Carpenter and A. J. Anderson found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before any human knows of the result. [ 19 ] The apparatus indicates one of two colors depending on the outcome. The human observer sees which color is indicated, but does not consciously know which outcome the color represents. A second human, the one who set up the apparatus, is told of the color and becomes conscious of the outcome, and the box is opened to check if the outcome matches. [ 15 ] However, it is disputed whether merely observing the color counts as a conscious observation of the outcome. [ 20 ] Bohr's interpretation Analysis of the work of Niels Bohr , one of the main scientists associated with the Copenhagen interpretation, suggests he viewed the state of the cat before the box is opened as indeterminate. The superposition itself had no physical meaning to Bohr: Schrödinger's cat would be either dead or alive long before the box is opened but the cat and box form an inseparable combination. [ 21 ] Bohr saw no role for a human observer. [ 22 ] : 35 Bohr emphasized the classical nature of measurement results. An "irreversible" or effectively irreversible process imparts the classical behavior of "observation" or "measurement". [ 23 ] [ 24 ] [ 25 ] Many-worlds interpretation The quantum-mechanical "Schrödinger's cat" paradox according to the many-worlds interpretation. In this interpretation, every event is a branch point. The cat is both alive and dead—regardless of whether the box is opened—but the "alive" and "dead" cats are in different branches of the universe that are equally real but cannot interact with each other. In 1957, Hugh Everett formulated the many-worlds interpretation of quantum mechanics, which does not single out observation as a special process. In the many-worlds interpretation, both alive and dead states of the cat persist after the box is opened, but are decoherent from each other. In other words, when the box is opened, the observer and the possibly-dead cat split into an observer looking at a box with a dead cat and an observer looking at a box with a live cat. But since the dead and alive states are decoherent, there is no communication or interaction between them. When opening the box, the observer becomes entangled with the cat, so "observer states" corresponding to the cat's being alive and dead are formed; each observer state is entangled , or linked, with the cat so that the observation of the cat's state and the cat's state correspond with each other. Quantum decoherence ensures that the different outcomes have no interaction with each other. Decoherence is generally considered to prevent simultaneous observation of multiple states. [ 26 ] [ 27 ] A variant of the Schrödinger's cat experiment, known as the quantum suicide machine, has been proposed by cosmologist Max Tegmark . It examines the Schrödinger's cat experiment from the point of view of the cat, and argues that by using this approach, one may be able to distinguish between the Copenhagen interpretation and many-worlds. [ citation needed ] Ensemble interpretation In Ensemble interpretations , superpositions are sub-ensembles of a larger statistical ensemble. The state vector would not apply to individual cat experiments, but only to the statistics of many similarly prepared cat experiments. Proponents of these interpretations argue that this makes the Schrödinger's cat paradox a trivial matter, or a non-issue. When the physicist opens the box, they simply discover which subensemble that specific cat belonged to. [ 28 ] Relational interpretation The relational interpretation makes no fundamental distinction between the human experimenter, the cat, and the apparatus or between animate and inanimate systems; all are quantum systems governed by the same rules of wavefunction evolution , and all may be considered "observers". But the relational interpretation allows that different observers can give different accounts of the same series of events, depending on the information they have about the system. [ 29 ] [ non-primary source needed ] The cat can be considered an observer of the apparatus; meanwhile, the experimenter can be considered another observer of the system in the box (the cat plus the apparatus). Before the box is opened, the cat, by nature of its being alive or dead, has information about the state of the apparatus (the atom has either decayed or not decayed); but the experimenter does not have information about the state of the box contents. In this way, the two observers simultaneously have different accounts of the situation: To the cat, the wavefunction of the apparatus has appeared to "collapse"; to the experimenter, the contents of the box appear to be in superposition. Not until the box is opened, and both observers have the same information about what happened, do both system states appear to "collapse" into the same definite result, a cat that is either alive or dead. [ citation needed ] Transactional interpretation In the transactional interpretation the apparatus emits an advanced wave backward in time, which combined with the wave that the source emits forward in time, forms a standing wave. The waves are seen as physically real, and the apparatus is considered an "observer". In the transactional interpretation, the collapse of the wavefunction is "atemporal" and occurs along the whole transaction between the source and the apparatus. The cat is never in superposition. Rather the cat is only in one state at any particular time, regardless of when the human experimenter looks in the box. The transactional interpretation resolves this quantum paradox. [ 30 ] [ non-primary source needed ] Objective collapse theories According to objective collapse theories , superpositions are destroyed spontaneously (irrespective of external observation) when some objective physical threshold (of time, mass, temperature, irreversibility , etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is opened. This could loosely be phrased as "the cat observes itself" or "the environment observes the cat". Objective collapse theories require a modification of standard quantum mechanics to allow superpositions to be destroyed by the process of time evolution. [ 31 ] These theories could ideally be tested by creating mesoscopic superposition states in the experiment. For instance, energy cat states have been proposed as a precise detector of the quantum gravity related energy decoherence models. [ 32 ] Applications and tests Schrödinger's cat quantum superposition of states and effect of the environment through decoherence The experiment as described is a purely theoretical one, and the machine proposed is not known to have been constructed. However, successful experiments involving similar principles, e.g. superpositions of relatively large (by the standards of quantum physics) objects have been performed. [ 33 ] [ better source needed ] These experiments do not show that a cat-sized object can be superposed, but the known upper limit on " cat states " has been pushed upwards by them. In many cases the state is short-lived, even when cooled to near absolute zero . A "cat state" has been achieved with photons. [ 34 ] [ 35 ] A beryllium ion has been trapped in a superposed state. [ 36 ] An experiment involving a superconducting quantum interference device ("SQUID") has been linked to the theme of the thought experiment: "The superposition state does not correspond to a billion electrons flowing one way and a billion others flowing the other way. Superconducting electrons move en masse. All the superconducting electrons in the SQUID flow both ways around the loop at once when they are in the Schrödinger's cat state." [ 37 ] A piezoelectric "tuning fork" has been constructed, which can be placed into a superposition of vibrating and non vibrating states. The resonator comprises about 10 trillion atoms. [ 38 ] An experiment involving a flu virus has been proposed. [ 39 ] An experiment involving a bacterium and an electromechanical oscillator has been proposed. [ 40 ] In quantum computing the phrase "cat state" sometimes refers to the GHZ state , wherein several qubits are in an equal superposition of all being 0 and all being 1; e.g., According to at least one proposal, it may be possible to determine the state of the cat before observing it. [ 41 ] [ 42 ] In popular culture This drawing by F. Gwynplaine MacIntyre , originally published in Analog magazine, illustrates MacIntyre's science-fiction story "Schrödinger's Cat-Sitter". The cat is depicted simultaneously in front of and behind the impossible trident in an optical illusion . According to historian of science Robert P. Crease , Schrödinger's thought experiment did not become widely known until the 1970s. In 1972 Ursula K. Le Guin learned about it while researching quantum mechanics for her novel The Dispossessed ; Crease credits her 1974 short story "Schrödinger's Cat" with bringing the concept into popular culture. [ 43 ] Other science-fiction writers soon picked it up, often using it in a humorous vein. [ 44 ] Works of fiction have employed Schrödinger's thought experiment as plot device and as metaphor , in genres from apocalyptic science fiction to young-adult drama, making the cat more prominent in popular culture than in physics itself. [ 45 ] [ 46 ] [ 47 ] [ 48 ] Schrödinger's cat has been a motive in many science fiction works, and used as a title of a number of them, including Greg Bear 's "Schrödinger's Plague" ( Analog , 29 March 1982), George Alec Effinger 's " Schrödinger's Kitten " ( Omni , September 1988), F. Gwynplaine MacIntyre 's "Schrödinger's Cat-Sitter" ( Analog , July/August 2001), Rudy Rucker 's "Schrödinger's Cat" ( Analog , 30 March 1981), and Robert Anton Wilson 's Schrödinger's Cat Trilogy (1988), illustrating various interpretations of quantum physics . [ 49 ] [ 50 ] In addition to novels and short stories, Schrödinger's cat has appeared in film, [ 51 ] [ 52 ] [ 53 ] [ 54 ] poetry, [ 55 ] [ 56 ] theatre, [ 57 ] [ 58 ] live-action television, [ 59 ] cartoons, [ 60 ] [ 61 ] [ 62 ] music, [ 63 ] and webcomics. [ 45 ] See also Basis function Cat state Complementarity (physics) Double-slit experiment Elitzur–Vaidman bomb tester Heisenberg cut Modal realism Observer effect (physics) Ray cat Schroedinbug References ^ a b c Schrödinger, Erwin (November 1935). "Die gegenwärtige Situation in der Quantenmechanik (The Present Situation in Quantum Mechanics)". Naturwissenschaften . 23 (48): 807– 812. Bibcode : 1935NW.....23..807S . doi : 10.1007/BF01491891 . S2CID 206795705 . Man kann auch ganz burleske Fälle konstruieren. Eine Katze wird in eine Stahlkammer gesperrt, zusammen mit folgender Höllenmaschine (die man gegen den direkten Zugriff der Katze sichern muß): in einem Geigerschen Zählrohr befindet sich eine winzige Menge radioaktiver Substanz, so wenig, daß im Laufe einer Stunde vielleicht eines von den Atomen zerfällt, ebenso wahrscheinlich aber auch keines; geschieht es, so spricht das Zählrohr an und betätigt über ein Relais ein Hämmerchen, das ein Kölbchen mit Blausäure zertrümmert. Hat man dieses ganze System eine Stunde lang sich selbst überlassen, so wird man sich sagen, daß die Katze noch lebt, wenn inzwischen kein Atom zerfallen ist. Der erste Atomzerfall würde sie vergiftet haben. Die Psi-Funktion des ganzen Systems würde das so zum Ausdruck bringen, daß in ihr die lebende und die tote Katze (s.v.v.) [sit venia verbo] zu gleichen Teilen gemischt oder verschmiert sind. Das Typische an solchen Fällen ist, daß eine ursprünglich auf den Atombereich beschränkte Unbestimmtheit sich in grobsinnliche Unbestimmtheit umsetzt, die sich dann durch direkte Beobachtung entscheiden läßt. Das hindert uns, in so naiver Weise ein "verwaschenes Modell" als Abbild der Wirklichkeit gelten zu lassen. An sich enthielte es nichts Unklares oder Widerspruchsvolles. Es ist ein Unterschied zwischen einer verwackelten oder unscharf eingestellten Photographie und einer Aufnahme von Wolken und Nebelschwaden. ^ Fine, Arthur . "The Einstein-Podolsky-Rosen Argument in Quantum Theory" . Stanford Encyclopedia of Philosophy . Retrieved June 11, 2020 . ^ Ball, Philip (June 25, 2018). "Real-Life Schrödinger's Cats Probe the Boundary of the Quantum World" . Quanta Magazine . Archived from the original on February 28, 2025 . Retrieved February 24, 2025 . ^ Einstein, A.; Podolsky, B.; Rosen, N. (May 15, 1935). "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?". Physical Review . 47 (10): 777– 780. doi : 10.1103/PhysRev.47.777 . ISSN 0031-899X . ^ a b c Fine, Arthur (2017). "The Einstein-Podolsky-Rosen Argument in Quantum Theory" . Stanford Encyclopedia of Philosophy . Stanford University . Retrieved April 11, 2021 . ^ a b c d e Baggott, J. E. (2013). The quantum story: a history in 40 moments (Impression: 3 ed.). Oxford: Oxford Univ. Press. ISBN 978-0-19-965597-7 . ^ Polkinghorne, J. C. (1985). The Quantum World . Princeton University Press . p. 67. ISBN 0-691-02388-3 . Archived from the original on May 19, 2015 . Retrieved November 20, 2020 . ^ Tetlow, Philip (2012). Understanding Information and Computation: From Einstein to Web Science . Gower Publishing, Ltd. p. 321. ISBN 978-1-4094-4040-6 . Archived from the original on May 19, 2015. ^ Lazarou, Dimitris (2007). "Interpretation of quantum theory - An overview". arXiv : 0712.3466 [ quant-ph ]. ^ Trimmer, John D. (1980). "The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper". Proceedings of the American Philosophical Society . 124 (5): 323– 338. JSTOR 986572 . The English translation here is based on the German original, not on the inaccurate version in this source's translation of the entire article: Schrödinger: "The Present Situation in Quantum Mechanics." 5. Are the Variables Really Blurred? ^ Maxwell, Nicholas (January 1, 1993). "Induction and Scientific Realism: Einstein versus van Fraassen Part Three: Einstein, Aim-Oriented Empiricism and the Discovery of Special and General Relativity". The British Journal for the Philosophy of Science . 44 (2): 275– 305. doi : 10.1093/bjps/44.2.275 . JSTOR 687649 . ^ Peres, Asher (January 1988). "Schrödinger's immortal cat" . Foundations of Physics . 18 (1): 57– 76. Bibcode : 1988FoPh...18...57P . doi : 10.1007/BF01882873 . ISSN 0015-9018 . ^ Schlosshauer, Maximilian (February 23, 2005). "Decoherence, the measurement problem, and interpretations of quantum mechanics" . Reviews of Modern Physics . 76 (4): 1267– 1305. arXiv : quant-ph/0312059 . Bibcode : 2004RvMP...76.1267S . doi : 10.1103/RevModPhys.76.1267 . ^ Wimmel, Hermann (1992). Quantum physics & observed reality: a critical interpretation of quantum mechanics . World Scientific. p. 2. ISBN 978-981-02-1010-6 . Archived from the original on May 20, 2013 . Retrieved May 9, 2011 . ^ a b Hobson, Art (2017). Tales of the Quantum: Understanding Physics' Most Fundamental Theory . New York, NY: Oxford University Press. pp. 200– 202. ISBN 978-0-19-067963-7 . Retrieved April 8, 2022 . ^ Omnès, Roland (1999). Understanding Quantum Mechanics . Princeton, New Jersey: Princeton University Press. pp. 60– 62. ISBN 0-691-00435-8 . Retrieved April 8, 2022 . ^ a b Levin, Frank S. (2017). Surfing the Quantum World . New York, NY: Oxford University Press. pp. 229– 232. ISBN 978-0-19-880827-5 . Retrieved April 8, 2022 . ^ Puri, Ravinder R. (2017). Non-Relativistic Quantum Mechanics . Cambridge, United Kingdom: Cambridge University Press. p. 146. ISBN 978-1-107-16436-9 . Retrieved April 8, 2022 . ^ Carpenter RHS; Anderson AJ (2006). "The death of Schrödinger's cat and of consciousness-based wave-function collapse" (PDF) . Annales de la Fondation Louis de Broglie . 31 (1): 45– 52. Archived from the original (PDF) on November 30, 2006 . Retrieved September 10, 2010 . ^ Okón E, Sebastián MA (2016). "How to Back up or Refute Quantum Theories of Consciousness". Mind and Matter . 14 (1): 25– 49. ^ Faye, J (January 24, 2008). "Copenhagen Interpretation of Quantum Mechanics" . Stanford Encyclopedia of Philosophy . The Metaphysics Research Lab Center for the Study of Language and Information, Stanford University . Retrieved September 19, 2010 . ^ John Bell (1990). "Against 'measurement' ". Physics World . 3 (8): 33– 41. doi : 10.1088/2058-7058/3/8/26 . ^ Niels Bohr (1985) [May 16, 1947]. Jørgen Kalckar (ed.). Foundations of Quantum Physics I (1926-1932) . Niels Bohr: Collected Works. Vol. 6. pp. 451– 454. ^ Stig Stenholm (1983). "To fathom space and time". In Pierre Meystre (ed.). Quantum Optics, Experimental Gravitation, and Measurement Theory . Plenum Press. p. 121. The role of irreversibility in the theory of measurement has been emphasized by many. Only this way can a permanent record be obtained. The fact that separate pointer positions must be of the asymptotic nature usually associated with irreversibility has been utilized in the measurement theory of Daneri, Loinger and Prosperi (1962). It has been accepted as a formal representation of Bohr's ideas by Rosenfeld (1966). ^ Haake, Fritz (April 1, 1993). "Classical motion of meter variables in the quantum theory of measurement". Physical Review A . 47 (4): 2506– 2517. Bibcode : 1993PhRvA..47.2506H . doi : 10.1103/PhysRevA.47.2506 . PMID 9909217 . ^ Zurek, Wojciech H. (2003). "Decoherence, einselection, and the quantum origins of the classical". Reviews of Modern Physics . 75 (3): 715. arXiv : quant-ph/0105127 . Bibcode : 2003RvMP...75..715Z . doi : 10.1103/revmodphys.75.715 . S2CID 14759237 . ^ Wojciech H. Zurek , "Decoherence and the transition from quantum to classical", Physics Today , 44, pp. 36–44 (1991) ^ Home, D.; Whitaker, M. A. B. (1992). "Ensemble Interpretations of Quantum Mechanics: A Modern Perspective". Physics Reports . 210 (4): 223– 317. Bibcode : 1992PhR...210..223H . doi : 10.1016/0370-1573(92)90088-H . ^ Rovelli, Carlo (1996). "Relational Quantum Mechanics". International Journal of Theoretical Physics . 35 (8): 1637– 1678. arXiv : quant-ph/9609002 . Bibcode : 1996IJTP...35.1637R . doi : 10.1007/BF02302261 . S2CID 16325959 . ^ Cramer, John G. (July 1986). "The transactional interpretation of quantum mechanics" . Reviews of Modern Physics . 58 (3): 647– 685. Bibcode : 1986RvMP...58..647C . doi : 10.1103/RevModPhys.58.647 . ^ Okon, Elias; Sudarsky, Daniel (February 1, 2014). "Benefits of Objective Collapse Models for Cosmology and Quantum Gravity". Foundations of Physics . 44 (2): 114– 143. arXiv : 1309.1730 . Bibcode : 2014FoPh...44..114O . doi : 10.1007/s10701-014-9772-6 . ISSN 1572-9516 . S2CID 67831520 . ^ Khazali, Mohammadsadegh; Lau, Hon Wai; Humeniuk, Adam; Simon, Christoph (August 11, 2016). "Large energy superpositions via Rydberg dressing". Physical Review A . 94 (2) 023408. arXiv : 1509.01303 . Bibcode : 2016PhRvA..94b3408K . doi : 10.1103/physreva.94.023408 . ISSN 2469-9926 . S2CID 118364289 . ^ "What is the world's biggest Schrodinger cat?" . stackexchange.com . Archived from the original on January 8, 2012. ^ "NIST Researchers Create 'Quantum Cats' Made of Light" . NIST . August 31, 2010. Archived from the original on May 7, 2017. ^ Sychev, Demid V.; Ulanov, Alexander E.; Pushkina, Anastasia A.; Richards, Matthew W.; Fedorov, Ilya A.; Lvovsky, Alexander I. (June 2017). "Enlargement of optical Schrödinger's cat states" . Nature Photonics . 11 (6): 379– 382. arXiv : 1609.08425 . Bibcode : 2017NaPho..11..379S . doi : 10.1038/nphoton.2017.57 . ISSN 1749-4885 . ^ Monroe, C.; Meekhof, D. M.; King, B. E.; Wineland, D. J. (May 24, 1996). "A "Schrödinger's cat" Superposition State of an Atom". Science . 272 (5265): 1131– 1136. Bibcode : 1996Sci...272.1131M . doi : 10.1126/science.272.5265.1131 . PMID 8662445 . S2CID 2311821 . ^ "Physics World: Schrödinger's cat comes into view " . July 5, 2000. ^ Castelvecchi, Davide. "Macro-Weirdness: "Quantum Microphone" Puts Naked-Eye Object in 2 Places at Once" . Scientific American . Archived from the original on March 19, 2012. ^ Romero-Isart, O.; Juan, M. L.; Quidant, R.; Cirac, J. I. (2010). "Toward Quantum Superposition of Living Organisms". New Journal of Physics . 12 (3) 033015. arXiv : 0909.1469 . Bibcode : 2010NJPh...12c3015R . doi : 10.1088/1367-2630/12/3/033015 . S2CID 59151724 . ^ "Could 'Schrödinger's bacterium' be placed in a quantum superposition?" . physicsworld.com . Archived from the original on July 30, 2016. ^ Najjar, Dana (November 7, 2019). "Physicists Can Finally Peek at Schrödinger's Cat Without Killing It Forever" . Live Science . Retrieved November 7, 2019 . ^ Patekar, Kartik; Hofmann, Holger F. (2019). "The role of system–meter entanglement in controlling the resolution and decoherence of quantum measurements" . New Journal of Physics . 21 (10): 103006. arXiv : 1905.09978 . Bibcode : 2019NJPh...21j3006P . doi : 10.1088/1367-2630/ab4451 . ^ Crease, Robert P. (May 27, 2024). "Ursula Le Guin: the pioneering author we should thank for popularizing Schrödinger's cat" . Physics World . Retrieved October 27, 2024 . ^ Sam Stall (May 1, 2007). 100 Cats Who Changed Civilization . Quirk Books. p. 34. ISBN 978-1-59474-163-0 . ^ a b Crease, Robert P. (2012). "The cat that never dies" . Physics World . 25 (4): 18– 19. Bibcode : 2012PhyW...25d..18C . doi : 10.1088/2058-7058/25/04/27 . ^ Ryan, Marie-Laure (2011). "Narrative/Science Entanglements: On the Thousand and One Literary Lives of Schrödinger's Cat" . Narrative . 19 (2): 171– 186. ISSN 1063-3685 . JSTOR 41289295 . ^ Kravitz, Bennett (2013). "Thoughts on the Anti-Detective in Paul Auster's "New York Trilogy", Adam Ross's "Mister Peanut", and Martha Grimes' "The Old Wine Shades" " . Studies in Popular Culture . 36 (1): 45– 61. ISSN 0888-5753 . JSTOR 23610151 . ^ Branzburg, Judith V. (October 31, 2000). "Dead cats and live bodies" . The Lesbian Review of Books . 7 (1): 3. ^ "SFE: Wilson, Robert Anton" . sf-encyclopedia.com . Retrieved December 3, 2022 . ^ "SFE: Thought Experiment" . sf-encyclopedia.com . Retrieved December 3, 2022 . ^ Goldberg, Matt (April 17, 2020). "A Serious Man Ending Explained: The Crucible of American Judaism" . Collider . Retrieved December 3, 2022 . ^ Orr, Christopher (September 25, 2014). "30 Years of Coens: A Serious Man" . The Atlantic . Archived from the original on December 3, 2022 . Retrieved December 3, 2022 . ^ Ebert, Roger (March 4, 2013). "The Coen Brothers and Serious Quantum Theory" . Chicago Sun Times . Archived from the original on October 29, 2020. ^ Collis, Clark (June 20, 2014). "Coherence" . Entertainment Weekly . Archived from the original on December 3, 2022 . Retrieved December 3, 2022 . ^ Landsman, Peggy (April 1, 2022). " "Schrodinger's Cat" " . Scientific American . Archived from the original on May 29, 2022 . Retrieved February 22, 2023 . ^ Robbins, Hollis. " "His Paws Upon The Dish" " . Per Contra Journal . Per Contra . Retrieved February 22, 2023 . ^ Ehren, Christine (November 18, 2001). "World Premiere Schrodinger's Girlfriend Closes Nov. 18 at San Fran's Magic" . Schrodingers Girlfriend . Playbill Review. Archived from the original on May 17, 2010 . Retrieved January 6, 2015 . ^ Hurwitt, Robert (November 5, 2001). " 'Girlfriend' runs out of inspiration / Ideas bog down physics comedy" . SFGate Review . Archived from the original on November 26, 2015 . Retrieved December 5, 2015 . ^ Mohan, Geoffrey (August 12, 2013). "Google doodle honors physicist Erwin Schrodinger and his cat" . Baltimore Sun . Archived from the original on December 2, 2022 . Retrieved December 2, 2022 . ^ Farrer, Gordon (January 6, 2006). "Sum thing to do with maths genius" . The Age . Melbourne. Archived from the original on January 15, 2008 . Retrieved August 28, 2007 . ^ Singh, Simon (October 2014). "Theories of quantum levity" . Physics World . 27 (10): 80. Bibcode : 2014PhyW...27j..80S . doi : 10.1088/2058-7058/27/10/41 . ISSN 0953-8585 . ^ "The Famous Schrodinger's Cat Thought Experiment Gets Brought to Life in an Off-Kilter Animation" . Open Culture . March 24, 2017. Archived from the original on December 2, 2022 . Retrieved December 2, 2022 . ^ "NIGHTMARE シュレーディンガーナイフ歌詞 – 歌詞探索【歌詞リリ】" . Lyrical Nonsense . Archived from the original on May 28, 2023 . Retrieved May 28, 2023 . Further reading Einstein, Albert ; Podolsky, Boris ; Rosen, Nathan (May 15, 1935). "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?" . Physical Review . 47 (10): 777– 780. Bibcode : 1935PhRv...47..777E . doi : 10.1103/PhysRev.47.777 . Leggett, Tony (August 2000). "New Life for Schrödinger's Cat" (PDF) . Physics World. pp. 23– 24 . Retrieved February 28, 2020 . An article on experiments with "cat state" superpositions in superconducting rings, in which the electrons go around the ring in two directions simultaneously. Trimmer, John D. (1980). "The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper". Proceedings of the American Philosophical Society . 124 (5): 323– 338. JSTOR 986572 . ( registration required ) Yam, Phillip (October 9, 2012). "Bringing Schrödinger's Cat to Life" . Scientific American . Retrieved February 28, 2020 . A description of investigations of quantum "cat states" and wave function collapse by Serge Haroche and David J. Wineland , for which they won the 2012 Nobel Prize in Physics . Violaris, M. (2023). A Physics Lab Inside Your Head: Quantum Thought Experiments as an Educational Tool . 2023 IEEE International Conference on Quantum Computing and Engineering (QCE). Bellevue, WA, USA. pp. 58– 67. arXiv : 2312.07840 . doi : 10.1109/QCE57702.2023.20325 . Reduction of the Schrödinger's cat to a simple quantum circuit . External links A spoken word version of this article (created from a revision of the article dated 2013-08-12). Schrödinger's Cat from the Information Philosopher. Schrödinger's Cat - Sixty Symbols - a video published by the University of Nottingham . Schrödinger's Cat - a podcast produced by Sift.
Markdown	[Jump to content](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#bodyContent) Main menu Main menu move to sidebar hide Navigation - [Main page](https://en.wikipedia.org/wiki/Main_Page "Visit the main page [z]") - [Contents](https://en.wikipedia.org/wiki/Wikipedia:Contents "Guides to browsing Wikipedia") - [Current events](https://en.wikipedia.org/wiki/Portal:Current_events "Articles related to current events") - [Random article](https://en.wikipedia.org/wiki/Special:Random "Visit a randomly selected article [x]") - [About Wikipedia](https://en.wikipedia.org/wiki/Wikipedia:About "Learn about Wikipedia and how it works") - [Contact us](https://en.wikipedia.org/wiki/Wikipedia:Contact_us "How to contact Wikipedia") Contribute - [Help](https://en.wikipedia.org/wiki/Help:Contents "Guidance on how to use and edit Wikipedia") - [Learn to edit](https://en.wikipedia.org/wiki/Help:Introduction "Learn how to edit Wikipedia") - [Community portal](https://en.wikipedia.org/wiki/Wikipedia:Community_portal "The hub for editors") - [Recent changes](https://en.wikipedia.org/wiki/Special:RecentChanges "A list of recent changes to Wikipedia [r]") - [Upload file](https://en.wikipedia.org/wiki/Wikipedia:File_upload_wizard "Add images or other media for use on Wikipedia") - [Special pages](https://en.wikipedia.org/wiki/Special:SpecialPages "A list of all special pages [q]") [![](https://en.wikipedia.org/static/images/icons/enwiki-25.svg) ![Wikipedia](https://en.wikipedia.org/static/images/mobile/copyright/wikipedia-wordmark-en-25.svg) ![The Free Encyclopedia](https://en.wikipedia.org/static/images/mobile/copyright/wikipedia-tagline-en-25.svg)](https://en.wikipedia.org/wiki/Main_Page) [Search](https://en.wikipedia.org/wiki/Special:Search "Search Wikipedia [f]") Appearance - [Donate](https://donate.wikimedia.org/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en) - [Create account](https://en.wikipedia.org/w/index.php?title=Special:CreateAccount&returnto=Schr%C3%B6dinger%27s+cat "You are encouraged to create an account and log in; however, it is not mandatory") - [Log in](https://en.wikipedia.org/w/index.php?title=Special:UserLogin&returnto=Schr%C3%B6dinger%27s+cat "You're encouraged to log in; however, it's not mandatory. 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[o]") ## Contents move to sidebar hide - [(Top)](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat) - [1 Origin and motivation](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Origin_and_motivation) - [2 Thought experiment](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Thought_experiment) - [3 Analysis](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Analysis) - [4 Interpretations](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Interpretations) Toggle Interpretations subsection - [4\.1 Copenhagen interpretation](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Copenhagen_interpretation) - [4\.2 Role of consciousness](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Role_of_consciousness) - [4\.3 Bohr's interpretation](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Bohr's_interpretation) - [4\.4 Many-worlds interpretation](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Many-worlds_interpretation) - [4\.5 Ensemble interpretation](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Ensemble_interpretation) - [4\.6 Relational interpretation](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Relational_interpretation) - [4\.7 Transactional interpretation](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Transactional_interpretation) - [4\.8 Objective collapse theories](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Objective_collapse_theories) - [5 Applications and tests](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Applications_and_tests) - [6 In popular culture](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#In_popular_culture) - [7 See also](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#See_also) - [8 References](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#References) - [9 Further reading](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Further_reading) - [10 External links](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#External_links) Toggle the table of contents # Schrödinger's cat 79 languages - [Afrikaans](https://af.wikipedia.org/wiki/Schr%C3%B6dinger_se_kat "Schrödinger se kat – Afrikaans") - [العربية](https://ar.wikipedia.org/wiki/%D9%82%D8%B7%D8%A9_%D8%B4%D8%B1%D9%88%D8%AF%D9%86%D8%BA%D8%B1 "قطة شرودنغر – Arabic") - [Asturianu](https://ast.wikipedia.org/wiki/Gatu_de_Schr%C3%B6dinger "Gatu de Schrödinger – Asturian") - [Azərbaycanca](https://az.wikipedia.org/wiki/%C5%9Eredingerin_pi%C5%9Fiyi "Şredingerin pişiyi – Azerbaijani") - [تۆرکجه](https://azb.wikipedia.org/wiki/%D8%B4%D8%B1%D9%88%D8%AF%DB%8C%D9%86%D9%82%D8%B1%DB%8C%D9%86_%D9%BE%DB%8C%D8%B4%DB%8C%DA%AF%DB%8C "شرودینقرین پیشیگی – South Azerbaijani") - [Беларуская](https://be.wikipedia.org/wiki/%D0%9A%D0%BE%D1%82_%D0%A8%D1%80%D0%BE%D0%B4%D0%B7%D1%96%D0%BD%D0%B3%D0%B5%D1%80%D0%B0 "Кот Шродзінгера – Belarusian") - [Български](https://bg.wikipedia.org/wiki/%D0%9A%D0%BE%D1%82%D0%BA%D0%B0_%D0%BD%D0%B0_%D0%A8%D1%80%D1%8C%D0%BE%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80 "Котка на Шрьодингер – Bulgarian") - [বাংলা](https://bn.wikipedia.org/wiki/%E0%A6%B6%E0%A7%8D%E0%A6%B0%E0%A7%8B%E0%A6%A1%E0%A6%BF%E0%A6%99%E0%A7%8D%E0%A6%97%E0%A6%BE%E0%A6%B0%E0%A7%87%E0%A6%B0_%E0%A6%AC%E0%A6%BF%E0%A6%A1%E0%A6%BC%E0%A6%BE%E0%A6%B2 "শ্রোডিঙ্গারের বিড়াল – Bangla") - [বিষ্ণুপ্রিয়া মণিপুরী](https://bpy.wikipedia.org/wiki/%E0%A6%B6%E0%A7%8D%E0%A6%B0%E0%A7%8B%E0%A6%A1%E0%A6%BF%E0%A6%99%E0%A7%8D%E0%A6%97%E0%A6%BE%E0%A6%B0%E0%A6%B0_%E0%A6%AE%E0%A7%87%E0%A6%95%E0%A7%81%E0%A6%B0 "শ্রোডিঙ্গারর মেকুর – Bishnupriya") - [Català](https://ca.wikipedia.org/wiki/Gat_de_Schr%C3%B6dinger "Gat de Schrödinger – Catalan") - [Čeština](https://cs.wikipedia.org/wiki/Schr%C3%B6dingerova_ko%C4%8Dka "Schrödingerova kočka – Czech") - [Чӑвашла](https://cv.wikipedia.org/wiki/%D0%A8%D1%80%D1%91%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80_%D0%BA%D1%83%D1%88%D0%B0%D0%BA%C4%95 "Шрёдингер кушакĕ – Chuvash") - [Dansk](https://da.wikipedia.org/wiki/Schr%C3%B6dingers_kat "Schrödingers kat – Danish") - [Deutsch](https://de.wikipedia.org/wiki/Schr%C3%B6dingers_Katze "Schrödingers Katze – German") - [Zazaki](https://diq.wikipedia.org/wiki/P%C4%B1s%C4%B1nga_Schr%C3%B6dingeri "Pısınga Schrödingeri – Dimli") - [Ελληνικά](https://el.wikipedia.org/wiki/%CE%93%CE%AC%CF%84%CE%B1_%CF%84%CE%BF%CF%85_%CE%A3%CF%81%CE%AD%CE%BD%CF%84%CE%B9%CE%BD%CE%B3%CE%BA%CE%B5%CF%81 "Γάτα του Σρέντινγκερ – Greek") - [Esperanto](https://eo.wikipedia.org/wiki/Kato_de_Schr%C3%B6dinger "Kato de Schrödinger – Esperanto") - [Español](https://es.wikipedia.org/wiki/Gato_de_Schr%C3%B6dinger "Gato de Schrödinger – Spanish") - [Eesti](https://et.wikipedia.org/wiki/Schr%C3%B6dingeri_kass "Schrödingeri kass – Estonian") - [Euskara](https://eu.wikipedia.org/wiki/Schr%C3%B6dingerren_katua "Schrödingerren katua – Basque") - [فارسی](https://fa.wikipedia.org/wiki/%DA%AF%D8%B1%D8%A8%D9%87_%D8%B4%D8%B1%D9%88%D8%AF%DB%8C%D9%86%DA%AF%D8%B1 "گربه شرودینگر – Persian") - [Suomi](https://fi.wikipedia.org/wiki/Schr%C3%B6dingerin_kissa "Schrödingerin kissa – Finnish") - [Français](https://fr.wikipedia.org/wiki/Chat_de_Schr%C3%B6dinger "Chat de Schrödinger – French") - [Gaeilge](https://ga.wikipedia.org/wiki/Cat_Schr%C3%B6dinger "Cat Schrödinger – Irish") - [Galego](https://gl.wikipedia.org/wiki/Gato_de_Schr%C3%B6dinger "Gato de Schrödinger – Galician") - [עברית](https://he.wikipedia.org/wiki/%D7%94%D7%97%D7%AA%D7%95%D7%9C_%D7%A9%D7%9C_%D7%A9%D7%A8%D7%93%D7%99%D7%A0%D7%92%D7%A8 "החתול של שרדינגר – Hebrew") - [हिन्दी](https://hi.wikipedia.org/wiki/%E0%A4%B6%E0%A5%8D%E0%A4%B0%E0%A5%8B%E0%A4%A1%E0%A4%BF%E0%A4%82%E0%A4%97%E0%A4%B0_%E0%A4%95%E0%A5%80_%E0%A4%AC%E0%A4%BF%E0%A4%B2%E0%A5%8D%E0%A4%B2%E0%A5%80 "श्रोडिंगर की बिल्ली – Hindi") - [Hrvatski](https://hr.wikipedia.org/wiki/Schr%C3%B6dingerova_ma%C4%8Dka "Schrödingerova mačka – Croatian") - [Magyar](https://hu.wikipedia.org/wiki/Schr%C3%B6dinger_macsk%C3%A1ja "Schrödinger macskája – Hungarian") - [Հայերեն](https://hy.wikipedia.org/wiki/%D5%87%D6%80%D5%B5%D5%B8%D5%A4%D5%AB%D5%B6%D5%A3%D5%A5%D6%80%D5%AB_%D5%AF%D5%A1%D5%BF%D5%B8%D6%82 "Շրյոդինգերի կատու – Armenian") - [Interlingua](https://ia.wikipedia.org/wiki/Catto_de_Schr%C3%B6dinger "Catto de Schrödinger – Interlingua") - [Bahasa Indonesia](https://id.wikipedia.org/wiki/Kucing_Schr%C3%B6dinger "Kucing Schrödinger – Indonesian") - [Italiano](https://it.wikipedia.org/wiki/Paradosso_del_gatto_di_Schr%C3%B6dinger "Paradosso del gatto di Schrödinger – Italian") - [日本語](https://ja.wikipedia.org/wiki/%E3%82%B7%E3%83%A5%E3%83%AC%E3%83%BC%E3%83%87%E3%82%A3%E3%83%B3%E3%82%AC%E3%83%BC%E3%81%AE%E7%8C%AB "シュレーディンガーの猫 – Japanese") - [ქართული](https://ka.wikipedia.org/wiki/%E1%83%A8%E1%83%A0%E1%83%94%E1%83%93%E1%83%98%E1%83%9C%E1%83%92%E1%83%94%E1%83%A0%E1%83%98%E1%83%A1_%E1%83%99%E1%83%90%E1%83%A2%E1%83%90 "შრედინგერის კატა – Georgian") - [한국어](https://ko.wikipedia.org/wiki/%EC%8A%88%EB%A2%B0%EB%94%A9%EA%B1%B0%EC%9D%98_%EA%B3%A0%EC%96%91%EC%9D%B4 "슈뢰딩거의 고양이 – Korean") - [Kurdî](https://ku.wikipedia.org/wiki/Pis%C3%AEka_Schrodinger "Pisîka Schrodinger – Kurdish") - [Lietuvių](https://lt.wikipedia.org/wiki/%C5%A0riodingerio_kat%C4%97 "Šriodingerio katė – Lithuanian") - [Latviešu](https://lv.wikipedia.org/wiki/%C5%A0r%C4%93dingera_ka%C4%B7is "Šrēdingera kaķis – Latvian") - [Македонски](https://mk.wikipedia.org/wiki/%D0%A8%D1%80%D0%B5%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80%D0%BE%D0%B2%D0%B0_%D0%BC%D0%B0%D1%87%D0%BA%D0%B0 "Шредингерова мачка – Macedonian") - [മലയാളം](https://ml.wikipedia.org/wiki/%E0%B4%B7%E0%B5%8D%E0%B4%B0%E0%B5%8B%E0%B4%A1%E0%B4%BF%E0%B4%99%E0%B5%8D%E0%B4%99%E0%B4%B1%E0%B5%81%E0%B4%9F%E0%B5%86_%E0%B4%AA%E0%B5%82%E0%B4%9A%E0%B5%8D%E0%B4%9A "ഷ്രോഡിങ്ങറുടെ പൂച്ച – Malayalam") - [मराठी](https://mr.wikipedia.org/wiki/%E0%A4%B6%E0%A5%8D%E0%A4%B0%E0%A5%8D%E0%A4%AF%E0%A5%89%E0%A4%A1%E0%A4%BF%E0%A4%82%E0%A4%97%E0%A4%B0%E0%A4%9A%E0%A5%87_%E0%A4%AE%E0%A4%BE%E0%A4%82%E0%A4%9C%E0%A4%B0 "श्र्यॉडिंगरचे मांजर – Marathi") - [Bahasa Melayu](https://ms.wikipedia.org/wiki/Kucing_Schr%C3%B6dinger "Kucing Schrödinger – Malay") - [مازِرونی](https://mzn.wikipedia.org/wiki/%D8%B4%D8%B1%D9%88%D8%AF%DB%8C%D9%86%DA%AF%D8%B1_%D8%A8%D8%A7%D9%85%D8%B4%DB%8C "شرودینگر بامشی – Mazanderani") - [Nederlands](https://nl.wikipedia.org/wiki/Schr%C3%B6dingers_kat "Schrödingers kat – Dutch") - [Norsk nynorsk](https://nn.wikipedia.org/wiki/Schr%C3%B6dingers_katt "Schrödingers katt – Norwegian Nynorsk") - [Norsk bokmål](https://no.wikipedia.org/wiki/Schr%C3%B6dingers_katt "Schrödingers katt – Norwegian Bokmål") - [Occitan](https://oc.wikipedia.org/wiki/Gat_de_Schr%C3%B6dinger "Gat de Schrödinger – Occitan") - [ଓଡ଼ିଆ](https://or.wikipedia.org/wiki/%E0%AC%B8%E0%AD%8D%E0%AC%95%E0%AD%8D%E0%AC%B0%E0%AD%8B%E0%AC%A1%E0%AC%BF%E0%AC%99%E0%AD%8D%E0%AC%97%E0%AC%B0%E0%AC%99%E0%AD%8D%E0%AC%95_%E0%AC%AC%E0%AC%BF%E0%AC%B0%E0%AC%BE%E0%AC%A1%E0%AC%BC%E0%AC%BF "ସ୍କ୍ରୋଡିଙ୍ଗରଙ୍କ ବିରାଡ଼ି – Odia") - [ਪੰਜਾਬੀ](https://pa.wikipedia.org/wiki/%E0%A8%B8%E0%A8%BC%E0%A8%B0%E0%A9%8B%E0%A8%A1%E0%A8%BF%E0%A9%B0%E0%A8%97%E0%A8%B0_%E0%A8%A6%E0%A9%80_%E0%A8%AC%E0%A8%BF%E0%A9%B1%E0%A8%B2%E0%A9%80 "ਸ਼ਰੋਡਿੰਗਰ ਦੀ ਬਿੱਲੀ – Punjabi") - [Polski](https://pl.wikipedia.org/wiki/Kot_Schr%C3%B6dingera "Kot Schrödingera – Polish") - [پنجابی](https://pnb.wikipedia.org/wiki/%D8%B4%D8%B1%D9%88%DA%88%D9%86%DA%AF%D8%B1_%D8%AF%DB%8C_%D8%A8%D9%84%DB%8C "شروڈنگر دی بلی – Western Punjabi") - [Português](https://pt.wikipedia.org/wiki/Gato_de_Schr%C3%B6dinger "Gato de Schrödinger – Portuguese") - [Română](https://ro.wikipedia.org/wiki/Pisica_lui_Schr%C3%B6dinger "Pisica lui Schrödinger – Romanian") - [Русский](https://ru.wikipedia.org/wiki/%D0%9A%D0%BE%D1%82_%D0%A8%D1%80%D1%91%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80%D0%B0 "Кот Шрёдингера – Russian") - [Саха тыла](https://sah.wikipedia.org/wiki/%D0%A8%D1%80%D1%91%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80_%D0%BA%D1%83%D0%BE%D1%81%D0%BA%D0%B0%D1%82%D0%B0 "Шрёдингер куоската – Yakut") - [Sicilianu](https://scn.wikipedia.org/wiki/Jattu_di_Schr%C3%B6dinger "Jattu di Schrödinger – Sicilian") - [Srpskohrvatski / српскохрватски](https://sh.wikipedia.org/wiki/Schr%C3%B6dingerova_ma%C4%8Dka "Schrödingerova mačka – Serbo-Croatian") - [Simple English](https://simple.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat "Schrödinger's cat – Simple English") - [Slovenščina](https://sl.wikipedia.org/wiki/Schr%C3%B6dingerjeva_ma%C4%8Dka "Schrödingerjeva mačka – Slovenian") - [Српски / srpski](https://sr.wikipedia.org/wiki/%D0%A8%D1%80%D0%B5%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80%D0%BE%D0%B2%D0%B0_%D0%BC%D0%B0%D1%87%D0%BA%D0%B0 "Шредингерова мачка – Serbian") - [Svenska](https://sv.wikipedia.org/wiki/Schr%C3%B6dingers_katt "Schrödingers katt – Swedish") - [Ślůnski](https://szl.wikipedia.org/wiki/Kot_%C3%B4d_Schr%C3%B6dingera "Kot ôd Schrödingera – Silesian") - [தமிழ்](https://ta.wikipedia.org/wiki/%E0%AE%9A%E0%AF%81%E0%AE%B0%E0%AF%8B%E0%AE%9F%E0%AE%BF%E0%AE%99%E0%AF%8D%E0%AE%95%E0%AE%B0%E0%AE%BF%E0%AE%A9%E0%AF%8D_%E0%AE%AA%E0%AF%82%E0%AE%A9%E0%AF%88 "சுரோடிங்கரின் பூனை – Tamil") - [తెలుగు](https://te.wikipedia.org/wiki/%E0%B0%B7%E0%B1%8D%E0%B0%B0%E0%B1%8B%E0%B0%A1%E0%B0%BF%E0%B0%82%E0%B0%97%E0%B0%B0%E0%B1%8D_%E0%B0%AA%E0%B0%BF%E0%B0%B2%E0%B1%8D%E0%B0%B2%E0%B0%BF "ష్రోడింగర్ పిల్లి – Telugu") - [ไทย](https://th.wikipedia.org/wiki/%E0%B9%81%E0%B8%A1%E0%B8%A7%E0%B8%82%E0%B8%AD%E0%B8%87%E0%B8%8A%E0%B9%80%E0%B8%A3%E0%B8%AD%E0%B8%94%E0%B8%B4%E0%B8%87%E0%B9%80%E0%B8%87%E0%B8%AD%E0%B8%A3%E0%B9%8C "แมวของชเรอดิงเงอร์ – Thai") - [Türkmençe](https://tk.wikipedia.org/wiki/%C5%9Er%C3%BDodingeri%C5%88_pi%C5%9Figi "Şrýodingeriň pişigi – Turkmen") - [Tagalog](https://tl.wikipedia.org/wiki/Pusa_ni_Schr%C3%B6dinger "Pusa ni Schrödinger – Tagalog") - [Türkçe](https://tr.wikipedia.org/wiki/Schr%C3%B6dinger%27in_kedisi "Schrödinger'in kedisi – Turkish") - [Татарча / tatarça](https://tt.wikipedia.org/wiki/%D0%A8%D1%80%D3%A9%D0%B4%D0%B8%D0%BD%D0%B3%D0%B5%D1%80_%D0%BC%D3%99%D1%87%D0%B5%D1%81%D0%B5 "Шрөдингер мәчесе – Tatar") - [Українська](https://uk.wikipedia.org/wiki/%D0%9A%D1%96%D1%82_%D0%A8%D1%80%D0%B5%D0%B4%D1%96%D0%BD%D0%B3%D0%B5%D1%80%D0%B0 "Кіт Шредінгера – Ukrainian") - [Oʻzbekcha / ўзбекча](https://uz.wikipedia.org/wiki/Schr%C3%B6dinger_mushugi "Schrödinger mushugi – Uzbek") - [Vèneto](https://vec.wikipedia.org/wiki/Paradoso_del_gato_de_Schr%C3%B6dinger "Paradoso del gato de Schrödinger – Venetian") - [Tiếng Việt](https://vi.wikipedia.org/wiki/Con_m%C3%A8o_c%E1%BB%A7a_Schr%C3%B6dinger "Con mèo của Schrödinger – Vietnamese") - [Winaray](https://war.wikipedia.org/wiki/Misay_nga_Schr%C3%B6ndinger "Misay nga Schröndinger – Waray") - [吴语](https://wuu.wikipedia.org/wiki/%E8%96%9B%E5%AE%9A%E8%B0%94%E7%8C%AB "薛定谔猫 – Wu") - [文言](https://zh-classical.wikipedia.org/wiki/%E8%96%9B%E5%AE%9A%E8%AB%A4%E4%B9%8B%E8%B2%93 "薛定諤之貓 – Literary Chinese") - [粵語](https://zh-yue.wikipedia.org/wiki/%E8%96%9B%E5%AE%9A%E8%AB%A4%E8%B2%93 "薛定諤貓 – Cantonese") - [中文](https://zh.wikipedia.org/wiki/%E8%96%9B%E5%AE%9A%E8%B0%94%E7%8C%AB "薛定谔猫 – Chinese") [Edit links](https://www.wikidata.org/wiki/Special:EntityPage/Q8588#sitelinks-wikipedia "Edit interlanguage links") - [Article](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat "View the content page [c]") - 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From Wikipedia, the free encyclopedia Thought experiment in quantum mechanics For other uses, see [Schrödinger's cat (disambiguation)](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat_\(disambiguation\) "Schrödinger's cat (disambiguation)"). [![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/91/Schrodingers_cat.svg/500px-Schrodingers_cat.svg.png)](https://en.wikipedia.org/wiki/File:Schrodingers_cat.svg) Schrödinger's cat: a cat, a flask of poison, and a [radioactive](https://en.wikipedia.org/wiki/Radioactive "Radioactive") source connected to a [Geiger counter](https://en.wikipedia.org/wiki/Geiger_counter "Geiger counter") are placed in a sealed box. As illustrated, the quantum description uses a superposition of an alive cat and one that has died. In [quantum mechanics](https://en.wikipedia.org/wiki/Quantum_mechanics "Quantum mechanics"), Schrödinger's cat is a [thought experiment](https://en.wikipedia.org/wiki/Thought_experiment "Thought experiment") concerning [quantum superposition](https://en.wikipedia.org/wiki/Quantum_superposition "Quantum superposition"). In the thought experiment, a hypothetical [cat](https://en.wikipedia.org/wiki/Cat "Cat") in a closed box may be considered to be simultaneously both alive and dead while it is unobserved, as a result of its fate being linked to a random [subatomic](https://en.wikipedia.org/wiki/Subatomic_particle "Subatomic particle") event that may or may not occur. This experiment, viewed this way, is described as a [paradox](https://en.wikipedia.org/wiki/Paradox "Paradox"). This thought experiment was devised by physicist [Erwin Schrödinger](https://en.wikipedia.org/wiki/Erwin_Schr%C3%B6dinger "Erwin Schrödinger") in 1935,[\[1\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1) in a discussion with [Albert Einstein](https://en.wikipedia.org/wiki/Albert_Einstein "Albert Einstein"),[\[2\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Fine-2) to illustrate what Schrödinger saw as the problems of [Niels Bohr](https://en.wikipedia.org/wiki/Niels_Bohr "Niels Bohr") and [Werner Heisenberg](https://en.wikipedia.org/wiki/Werner_Heisenberg "Werner Heisenberg")'s philosophical views on quantum mechanics. In Schrödinger's original formulation, a cat, a flask of poison, and a [radioactive](https://en.wikipedia.org/wiki/Radioactive "Radioactive") source are placed in a sealed box. If an internal radiation monitor such as a [Geiger counter](https://en.wikipedia.org/wiki/Geiger_counter "Geiger counter") detects radioactivity (a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. If no decaying atom triggers the monitor, the cat remains alive. Mathematically, the [wave function](https://en.wikipedia.org/wiki/Wave_function "Wave function") that describes the contents of the box is a combination, or [quantum superposition](https://en.wikipedia.org/wiki/Quantum_superposition "Quantum superposition"), of these two possibilities. Yet, when one looks in the box, one sees the cat either alive or dead, not both alive and dead. This poses the question of when exactly quantum superposition ends and reality resolves into one possibility or the other. Although originally a critique of Bohr and Heisenberg, Schrödinger's seemingly paradoxical thought experiment became part of the foundation of quantum mechanics. It is often featured in theoretical discussions of the [interpretations of quantum mechanics](https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics "Interpretations of quantum mechanics"), particularly in situations involving the [measurement problem](https://en.wikipedia.org/wiki/Measurement_problem "Measurement problem"). As a result, Schrödinger's cat has had enduring [appeal in popular culture](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat_in_popular_culture "Schrödinger's cat in popular culture"). The experiment is not intended to be actually performed on a cat, but rather as an easily understandable illustration of the behavior of atoms. Experiments at the atomic scale have been carried out, showing that very small objects may exist as superpositions, but superposing an object as large as a cat would pose considerable technical difficulties.[\[3\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-3) Fundamentally, the Schrödinger's cat experiment asks how long quantum superpositions last and when (or whether) they collapse. Different [interpretations of the mathematics of quantum mechanics](https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics "Interpretations of quantum mechanics") have been proposed that give different explanations for this process. ## Origin and motivation Unsolved problem in physics How does the quantum description of reality, which includes elements such as the superposition of states and wavefunction collapse or quantum decoherence, give rise to the reality we perceive? Another way of stating this question regards the measurement problem: What constitutes a "measurement" that apparently causes the wave function to collapse into a definite state? [More unsolved problems in physics](https://en.wikipedia.org/wiki/List_of_unsolved_problems_in_physics "List of unsolved problems in physics") Schrödinger intended his thought experiment as a discussion of the [EPR article](https://en.wikipedia.org/wiki/Einstein%E2%80%93Podolsky%E2%80%93Rosen_paradox "Einstein–Podolsky–Rosen paradox")—named after its authors [Einstein](https://en.wikipedia.org/wiki/Albert_Einstein "Albert Einstein"), [Podolsky](https://en.wikipedia.org/wiki/Boris_Podolsky "Boris Podolsky"), and [Rosen](https://en.wikipedia.org/wiki/Nathan_Rosen "Nathan Rosen")—in 1935.[\[4\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-4)[\[5\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5) The EPR article highlighted the counterintuitive nature of [quantum superpositions](https://en.wikipedia.org/wiki/Quantum_superposition "Quantum superposition"), in which a quantum system for two particles does not separate[\[6\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 150 even when the particles are detected far from their last point of contact. The EPR paper concludes with a claim that this lack of separability meant that quantum mechanics as a theory of reality was incomplete. Schrödinger and Einstein exchanged letters about Einstein's EPR article, in the course of which Einstein pointed out that the state of an [unstable](https://en.wikipedia.org/wiki/Unstable "Unstable") keg of [gunpowder](https://en.wikipedia.org/wiki/Gunpowder "Gunpowder") will, after a while, contain a superposition of both exploded and unexploded states.[\[5\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5) To further illustrate, Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a closed steel chamber, wherein the cat's life or death depended on the state of a [radioactive](https://en.wikipedia.org/wiki/Radioactive "Radioactive") atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the position taken by Bohr and Heisenberg would be that the cat remains both alive and dead until the state has been observed. Schrödinger did not wish to promote the idea of dead-and-live cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics,[\[1\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1) thus employing [reductio ad absurdum](https://en.wikipedia.org/wiki/Reductio_ad_absurdum "Reductio ad absurdum"). Since Schrödinger's time, various [interpretations of the mathematics of quantum mechanics](https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics "Interpretations of quantum mechanics") have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real, while others do not.[\[7\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Polkinghorne-7)[\[8\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Tetlow-8) Intended as a critique of ideas prevalent in 1935, the Schrödinger's cat thought experiment remains a [touchstone](https://en.wikipedia.org/wiki/Touchstone_\(metaphor\) "Touchstone (metaphor)") for modern interpretations of quantum mechanics and can be used to illustrate and compare their strengths and weaknesses.[\[9\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-9)\[[better source needed](https://en.wikipedia.org/wiki/Wikipedia:Verifiability#Questionable_sources "Wikipedia:Verifiability")\] ## Thought experiment [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5e/Schroedinger_cat.jpg/330px-Schroedinger_cat.jpg)](https://en.wikipedia.org/wiki/File:Schroedinger_cat.jpg) A life-size cat figure in the garden of Huttenstrasse 9, Zurich, where [Erwin Schrödinger](https://en.wikipedia.org/wiki/Erwin_Schr%C3%B6dinger "Erwin Schrödinger") lived from 1921 to 1926. Depending on the light conditions, the figure appears to be either a live cat or a dead one. Schrödinger wrote:[\[1\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1)[\[10\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-10) > One can contrive even completely burlesque \[farcical\] cases. A cat is put in a steel chamber along with the following infernal device (which must be secured against direct interference by the cat): in a [Geiger counter](https://en.wikipedia.org/wiki/Geiger_counter "Geiger counter"), there is a tiny amount of radioactive substance, so tiny that in the course of an hour one of the atoms will perhaps decay, but also, with equal probability, that none of them will; if it does happen, the counter tube will discharge and through a relay release a hammer that will shatter a small flask of [hydrocyanic acid](https://en.wikipedia.org/wiki/Hydrocyanic_acid "Hydrocyanic acid"). If one has left this entire system to itself for an hour, one would tell oneself that the cat is still alive if no atom has [decayed](https://en.wikipedia.org/wiki/Radioactive_decay "Radioactive decay") in the meantime. Even a single atomic decay would have poisoned it. The [psi-function](https://en.wikipedia.org/wiki/Wave_function "Wave function") of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or spread out in equal parts. > > It is typical of these cases that an indeterminacy originally restricted to the atomic domain turns into a sensually observable \[macroscopic\] indeterminacy, which can then be resolved by direct observation. This prevents us from so naïvely accepting a "blurred model" as representative of reality. Per se, it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks. Schrödinger developed his famous [thought experiment](https://en.wikipedia.org/wiki/Thought_experiment "Thought experiment") in correspondence with Einstein. He suggested this 'quite ridiculous case' to illustrate his conclusion that the wave function cannot represent reality.[\[6\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 153 The wave function description of the complete cat system implies that the reality of the cat mixes the living and dead cat.[\[6\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 154 Einstein was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote:[\[6\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 157 > You are the only contemporary physicist, besides [Laue](https://en.wikipedia.org/wiki/Max_von_Laue "Max von Laue"), who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gun powder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation.[\[11\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-11) Note that the charge of gunpowder is not mentioned in Schrödinger's setup, which uses a Geiger counter as an amplifier and hydrocyanic poison instead of gunpowder. The gunpowder had been mentioned in Einstein's original suggestion to Schrödinger 15 years before, and Einstein carried it forward to the present discussion.[\[5\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5) ## Analysis In modern terms Schrödinger's hypothetical cat experiment describes the [measurement problem](https://en.wikipedia.org/wiki/Measurement_problem "Measurement problem"): quantum theory describes the cat system as a combination of two possible outcomes but only one outcome is ever observed.[\[12\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-PeresCat-12): 57 [\[13\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-SchlosshauerDecoherenceReview-13): 1269 The experiment poses the question, "when does a quantum system stop existing as a superposition of states and become one or the other?" (More technically, when does the actual quantum state stop being a non-trivial [linear combination](https://en.wikipedia.org/wiki/Linear_combination "Linear combination") of states, each of which resembles different classical states, and instead begin to have a unique classical description?) Standard microscopic quantum mechanics describes multiple possible outcomes of experiments but only one outcome is observed. The thought experiment illustrates this apparent paradox. Our intuition says that the cat cannot be in more than one state simultaneously—yet the quantum mechanical description of the thought experiment requires such a condition. ## Interpretations Since Schrödinger's time, other interpretations of quantum mechanics have been proposed that give different answers to the questions posed by Schrödinger's cat of how long superpositions last and when (or whether) they collapse. ### Copenhagen interpretation Main article: [Copenhagen interpretation](https://en.wikipedia.org/wiki/Copenhagen_interpretation "Copenhagen interpretation") A commonly held interpretation of quantum mechanics is the Copenhagen interpretation.[\[14\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Wimmel1992-14) In the Copenhagen interpretation, a measurement results in only one state of a superposition. This thought experiment makes apparent the fact that this interpretation simply provides no explanation for the state of the cat while the box is closed. The wavefunction description of the system consists of a superposition of the states "decayed nucleus/dead cat" and "undecayed nucleus/living cat". Only when the box is opened and observed can we make a statement about the cat.[\[6\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 157 ### Role of consciousness Main article: [Consciousness causes collapse](https://en.wikipedia.org/wiki/Consciousness_causes_collapse "Consciousness causes collapse") In 1932, [John von Neumann](https://en.wikipedia.org/wiki/John_von_Neumann "John von Neumann") described in his book [Mathematical Foundations of Quantum Mechanics](https://en.wikipedia.org/wiki/Mathematical_Foundations_of_Quantum_Mechanics "Mathematical Foundations of Quantum Mechanics") a pattern where the radioactive source is observed by a device, which itself is observed by another device and so on. It makes no difference in the predictions of quantum theory where along this chain of causal effects the superposition collapses.[\[15\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Tales_of_the_Quantum-15) This potentially infinite chain could be broken if the last device is replaced by a conscious observer. This solved the problem because it was claimed that an individual's consciousness cannot be multiple.[\[16\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-16) Eugene Wigner asserted that an observer is necessary for a collapse to one or the other (e.g., either a live cat or a dead cat) of the terms on the right-hand side of a [wave function](https://en.wikipedia.org/wiki/Wave_function "Wave function"). Wigner discussed the interpretation in a thought experiment known as [Wigner's friend](https://en.wikipedia.org/wiki/Wigner%27s_friend "Wigner's friend").[\[17\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Surfing_the_Quantum_World-17) Wigner supposed that a friend opened the box and observed the cat without telling anyone. From Wigner's conscious perspective, the friend is now part of the wave function and has seen a live cat and seen a dead cat. To a third person's conscious perspective, Wigner himself becomes part of the wave function once Wigner learns the outcome from the friend. This could be extended indefinitely.[\[17\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Surfing_the_Quantum_World-17) A resolution of the paradox is that the triggering of the Geiger counter counts as a measurement of the state of the radioactive substance. Because a measurement has already occurred deciding the state of the cat, the subsequent observation by a human records only what has already occurred.[\[18\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-18) Analysis of an actual experiment by [Roger Carpenter](https://en.wikipedia.org/wiki/Roger_Carpenter "Roger Carpenter") and A. J. Anderson found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before any human knows of the result.[\[19\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Carpenter2006-19) The apparatus indicates one of two colors depending on the outcome. The human observer sees which color is indicated, but does not consciously know which outcome the color represents. A second human, the one who set up the apparatus, is told of the color and becomes conscious of the outcome, and the box is opened to check if the outcome matches.[\[15\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Tales_of_the_Quantum-15) However, it is disputed whether merely observing the color counts as a conscious observation of the outcome.[\[20\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Okon2006-20) ### Bohr's interpretation Analysis of the work of [Niels Bohr](https://en.wikipedia.org/wiki/Niels_Bohr "Niels Bohr"), one of the main scientists associated with the Copenhagen interpretation, suggests he viewed the state of the cat before the box is opened as indeterminate. The superposition itself had no physical meaning to Bohr: Schrödinger's cat would be either dead or alive long before the box is opened but the cat and box form an inseparable combination.[\[21\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Faye2008-21) Bohr saw no role for a human observer.[\[22\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-22): 35 Bohr emphasized the classical nature of measurement results. An "irreversible" or effectively irreversible process imparts the classical behavior of "observation" or "measurement".[\[23\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-23)[\[24\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-24)[\[25\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-25) ### Many-worlds interpretation Main article: [Many-worlds interpretation](https://en.wikipedia.org/wiki/Many-worlds_interpretation "Many-worlds interpretation") [![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Schroedingers_cat_film.svg/250px-Schroedingers_cat_film.svg.png)](https://en.wikipedia.org/wiki/File:Schroedingers_cat_film.svg) The quantum-mechanical "Schrödinger's cat" paradox according to the many-worlds interpretation. In this interpretation, every event is a branch point. The cat is both alive and dead—regardless of whether the box is opened—but the "alive" and "dead" cats are in different branches of the universe that are equally real but cannot interact with each other. In 1957, [Hugh Everett](https://en.wikipedia.org/wiki/Hugh_Everett "Hugh Everett") formulated the many-worlds interpretation of quantum mechanics, which does not single out observation as a special process. In the many-worlds interpretation, both alive and dead states of the cat persist after the box is opened, but are [decoherent](https://en.wikipedia.org/wiki/Quantum_decoherence "Quantum decoherence") from each other. In other words, when the box is opened, the observer and the possibly-dead cat split into an observer looking at a box with a dead cat and an observer looking at a box with a live cat. But since the dead and alive states are decoherent, there is no communication or interaction between them. When opening the box, the observer becomes entangled with the cat, so "observer states" corresponding to the cat's being alive and dead are formed; each observer state is [entangled](https://en.wikipedia.org/wiki/Quantum_entanglement "Quantum entanglement"), or linked, with the cat so that the observation of the cat's state and the cat's state correspond with each other. Quantum decoherence ensures that the different outcomes have no interaction with each other. Decoherence is generally considered to prevent simultaneous observation of multiple states.[\[26\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-zurek03-26)[\[27\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-zurek91-27) A variant of the Schrödinger's cat experiment, known as the [quantum suicide](https://en.wikipedia.org/wiki/Quantum_suicide_and_immortality "Quantum suicide and immortality") machine, has been proposed by cosmologist [Max Tegmark](https://en.wikipedia.org/wiki/Max_Tegmark "Max Tegmark"). It examines the Schrödinger's cat experiment from the point of view of the cat, and argues that by using this approach, one may be able to distinguish between the Copenhagen interpretation and many-worlds.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] ### Ensemble interpretation In [Ensemble interpretations](https://en.wikipedia.org/wiki/Ensemble_interpretation "Ensemble interpretation"), superpositions are sub-ensembles of a larger statistical ensemble. The state vector would not apply to individual cat experiments, but only to the statistics of many similarly prepared cat experiments. Proponents of these interpretations argue that this makes the Schrödinger's cat paradox a trivial matter, or a non-issue. When the physicist opens the box, they simply discover which subensemble that specific cat belonged to.[\[28\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-28) ### Relational interpretation Main article: [Relational quantum mechanics](https://en.wikipedia.org/wiki/Relational_quantum_mechanics "Relational quantum mechanics") The [relational interpretation](https://en.wikipedia.org/wiki/Relational_quantum_mechanics "Relational quantum mechanics") makes no fundamental distinction between the human experimenter, the cat, and the apparatus or between animate and inanimate systems; all are quantum systems governed by the same rules of wavefunction [evolution](https://en.wikipedia.org/wiki/Time_evolution "Time evolution"), and all may be considered "observers". But the relational interpretation allows that different observers can give different accounts of the same series of events, depending on the information they have about the system.[\[29\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-29)\[[non-primary source needed](https://en.wikipedia.org/wiki/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources "Wikipedia:No original research")\] The cat can be considered an observer of the apparatus; meanwhile, the experimenter can be considered another observer of the system in the box (the cat plus the apparatus). Before the box is opened, the cat, by nature of its being alive or dead, has information about the state of the apparatus (the atom has either decayed or not decayed); but the experimenter does not have information about the state of the box contents. In this way, the two observers simultaneously have different accounts of the situation: To the cat, the wavefunction of the apparatus has appeared to "collapse"; to the experimenter, the contents of the box appear to be in superposition. Not until the box is opened, and both observers have the same information about what happened, do both system states appear to "collapse" into the same definite result, a cat that is either alive or dead.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] ### Transactional interpretation In the [transactional interpretation](https://en.wikipedia.org/wiki/Transactional_interpretation "Transactional interpretation") the apparatus emits an advanced wave backward in time, which combined with the wave that the source emits forward in time, forms a standing wave. The waves are seen as physically real, and the apparatus is considered an "observer". In the transactional interpretation, the collapse of the wavefunction is "atemporal" and occurs along the whole transaction between the source and the apparatus. The cat is never in superposition. Rather the cat is only in one state at any particular time, regardless of when the human experimenter looks in the box. The transactional interpretation resolves this quantum paradox.[\[30\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-30)\[[non-primary source needed](https://en.wikipedia.org/wiki/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources "Wikipedia:No original research")\] ### Objective collapse theories According to [objective collapse theories](https://en.wikipedia.org/wiki/Objective-collapse_theory "Objective-collapse theory"), superpositions are destroyed spontaneously (irrespective of external observation) when some objective physical threshold (of time, mass, temperature, [irreversibility](https://en.wikipedia.org/wiki/Irreversibility "Irreversibility"), etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is opened. This could loosely be phrased as "the cat observes itself" or "the environment observes the cat". Objective collapse theories require a modification of standard quantum mechanics to allow superpositions to be destroyed by the process of time evolution.[\[31\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-31) These theories could ideally be tested by creating mesoscopic superposition states in the experiment. For instance, energy cat states have been proposed as a precise detector of the quantum gravity related energy decoherence models.[\[32\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-32) ## Applications and tests Schrödinger's cat quantum superposition of states and effect of the environment through decoherence The experiment as described is a purely theoretical one, and the machine proposed is not known to have been constructed. However, successful experiments involving similar principles, e.g. superpositions of [relatively large](https://en.wikipedia.org/wiki/Mesoscopic "Mesoscopic") (by the standards of quantum physics) objects have been performed.[\[33\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-33)\[[better source needed](https://en.wikipedia.org/wiki/Wikipedia:Verifiability#Questionable_sources "Wikipedia:Verifiability")\] These experiments do not show that a cat-sized object can be superposed, but the known upper limit on "[cat states](https://en.wikipedia.org/wiki/Cat_state "Cat state")" has been pushed upwards by them. In many cases the state is short-lived, even when cooled to near [absolute zero](https://en.wikipedia.org/wiki/Absolute_zero "Absolute zero"). - A "cat state" has been achieved with photons.[\[34\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-34)[\[35\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-35) - A beryllium ion has been trapped in a superposed state.[\[36\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-36) - An experiment involving a [superconducting quantum interference device](https://en.wikipedia.org/wiki/Superconducting_quantum_interference_device "Superconducting quantum interference device") ("SQUID") has been linked to the theme of the thought experiment: "The superposition state does not correspond to a billion electrons flowing one way and a billion others flowing the other way. Superconducting electrons move en masse. All the superconducting electrons in the SQUID flow both ways around the loop at once when they are in the Schrödinger's cat state."[\[37\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-37) - A [piezoelectric](https://en.wikipedia.org/wiki/Piezoelectric "Piezoelectric") "tuning fork" has been constructed, which can be placed into a superposition of vibrating and non vibrating states. The resonator comprises about 10 trillion atoms.[\[38\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-38) - An experiment involving a flu virus has been proposed.[\[39\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-39) - An experiment involving a bacterium and an electromechanical oscillator has been proposed.[\[40\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-40) In [quantum computing](https://en.wikipedia.org/wiki/Quantum_computing "Quantum computing") the phrase "cat state" sometimes refers to the [GHZ state](https://en.wikipedia.org/wiki/Greenberger%E2%80%93Horne%E2%80%93Zeilinger_state "Greenberger–Horne–Zeilinger state"), wherein several qubits are in an equal superposition of all being 0 and all being 1; e.g., \\| ψ ⟩ \= 1 2 ( \\| 00 … 0 ⟩ \+ \\| 11 … 1 ⟩ ) . {\\displaystyle \\|\\psi \\rangle ={\\frac {1}{\\sqrt {2}}}{\\bigg (}\\|00\\ldots 0\\rangle +\\|11\\ldots 1\\rangle {\\bigg )}.} ![{\\displaystyle \\|\\psi \\rangle ={\\frac {1}{\\sqrt {2}}}{\\bigg (}\\|00\\ldots 0\\rangle +\\|11\\ldots 1\\rangle {\\bigg )}.}](https://wikimedia.org/api/rest_v1/media/math/render/svg/26aac0fa72a1f19180f6d2914259cadd8f07be74) According to at least one proposal, it may be possible to determine the state of the cat before observing it.[\[41\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-LS-20191107-41)[\[42\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-NJP-20191001-42) ## In popular culture [![](https://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/SchroCat.jpg/250px-SchroCat.jpg)](https://en.wikipedia.org/wiki/File:SchroCat.jpg) This drawing by [F. Gwynplaine MacIntyre](https://en.wikipedia.org/wiki/F._Gwynplaine_MacIntyre "F. Gwynplaine MacIntyre"), originally published in [Analog](https://en.wikipedia.org/wiki/Analog_Science_Fiction_and_Fact "Analog Science Fiction and Fact") magazine, illustrates MacIntyre's science-fiction story "Schrödinger's Cat-Sitter". The cat is depicted simultaneously in front of and behind the [impossible trident](https://en.wikipedia.org/wiki/Impossible_trident "Impossible trident") in an [optical illusion](https://en.wikipedia.org/wiki/Optical_illusion "Optical illusion"). According to historian of science [Robert P. Crease](https://en.wikipedia.org/wiki/Robert_P._Crease "Robert P. Crease"), Schrödinger's thought experiment did not become widely known until the 1970s. In 1972 [Ursula K. Le Guin](https://en.wikipedia.org/wiki/Ursula_K._Le_Guin "Ursula K. Le Guin") learned about it while researching quantum mechanics for her novel [The Dispossessed](https://en.wikipedia.org/wiki/The_Dispossessed "The Dispossessed"); Crease credits her 1974 short story "Schrödinger's Cat" with bringing the concept into popular culture.[\[43\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-43) Other [science-fiction](https://en.wikipedia.org/wiki/Science_fiction "Science fiction") writers soon picked it up, often using it in a humorous vein.[\[44\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-100CCC-44) Works of fiction have employed Schrödinger's thought experiment as plot device and as [metaphor](https://en.wikipedia.org/wiki/Metaphor "Metaphor"), in genres from [apocalyptic science fiction](https://en.wikipedia.org/wiki/Apocalyptic_science_fiction "Apocalyptic science fiction") to young-adult drama, making the cat more prominent in popular culture than in physics itself.[\[45\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Crease-45)[\[46\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-46)[\[47\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-47)[\[48\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-48) Schrödinger's cat has been a motive in many science fiction works, and used as a title of a number of them, including [Greg Bear](https://en.wikipedia.org/wiki/Greg_Bear "Greg Bear")'s "Schrödinger's Plague" ([Analog](https://en.wikipedia.org/wiki/Analog_Science_Fiction_and_Fact "Analog Science Fiction and Fact"), 29 March 1982), [George Alec Effinger](https://en.wikipedia.org/wiki/George_Alec_Effinger "George Alec Effinger")'s "[Schrödinger's Kitten](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_Kitten "Schrödinger's Kitten")" ([Omni](https://en.wikipedia.org/wiki/Omni_\(magazine\) "Omni (magazine)"), September 1988), [F. Gwynplaine MacIntyre](https://en.wikipedia.org/wiki/F._Gwynplaine_MacIntyre "F. Gwynplaine MacIntyre")'s "Schrödinger's Cat-Sitter" (Analog, July/August 2001), [Rudy Rucker](https://en.wikipedia.org/wiki/Rudy_Rucker "Rudy Rucker")'s "Schrödinger's Cat" (Analog, 30 March 1981), and [Robert Anton Wilson](https://en.wikipedia.org/wiki/Robert_Anton_Wilson "Robert Anton Wilson")'s [Schrödinger's Cat Trilogy](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_Cat_Trilogy "Schrödinger's Cat Trilogy") (1988), illustrating various [interpretations of quantum physics](https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics "Interpretations of quantum mechanics").[\[49\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-49)[\[50\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-50) In addition to novels and short stories, Schrödinger's cat has appeared in film,[\[51\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-51)[\[52\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-52)[\[53\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-53)[\[54\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-54) poetry,[\[55\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-55)[\[56\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-56) theatre,[\[57\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger's_Girlfriend-57)[\[58\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Schrodingers_Girlfriend_SFG-58) live-action television,[\[59\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-59) cartoons,[\[60\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-The_Age-60)[\[61\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-61)[\[62\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-62) music,[\[63\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-63) and webcomics.[\[45\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Crease-45) ## See also - [![icon](https://upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Stylised_atom_with_three_Bohr_model_orbits_and_stylised_nucleus.svg/40px-Stylised_atom_with_three_Bohr_model_orbits_and_stylised_nucleus.svg.png)](https://en.wikipedia.org/wiki/File:Stylised_atom_with_three_Bohr_model_orbits_and_stylised_nucleus.svg)[Physics portal](https://en.wikipedia.org/wiki/Portal:Physics "Portal:Physics") - [Basis function](https://en.wikipedia.org/wiki/Basis_function "Basis function") - [Cat state](https://en.wikipedia.org/wiki/Cat_state "Cat state") - [Complementarity (physics)](https://en.wikipedia.org/wiki/Complementarity_\(physics\) "Complementarity (physics)") - [Double-slit experiment](https://en.wikipedia.org/wiki/Double-slit_experiment "Double-slit experiment") - [Elitzur–Vaidman bomb tester](https://en.wikipedia.org/wiki/Elitzur%E2%80%93Vaidman_bomb_tester "Elitzur–Vaidman bomb tester") - [Heisenberg cut](https://en.wikipedia.org/wiki/Heisenberg_cut "Heisenberg cut") - [Modal realism](https://en.wikipedia.org/wiki/Modal_realism "Modal realism") - [Observer effect (physics)](https://en.wikipedia.org/wiki/Observer_effect_\(physics\) "Observer effect (physics)") - [Ray cat](https://en.wikipedia.org/wiki/Ray_cat "Ray cat") - [Schroedinbug](https://en.wikipedia.org/wiki/Schroedinbug "Schroedinbug") ## References 1. ^ [*a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-1) [c](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-2) [Schrödinger, Erwin](https://en.wikipedia.org/wiki/Erwin_Schr%C3%B6dinger "Erwin Schrödinger") (November 1935). "Die gegenwärtige Situation in der Quantenmechanik (The Present Situation in Quantum Mechanics)". [Naturwissenschaften](https://en.wikipedia.org/wiki/Naturwissenschaften "Naturwissenschaften"). 23* (48): 807–812\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1935NW.....23..807S](https://ui.adsabs.harvard.edu/abs/1935NW.....23..807S). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1007/BF01491891](https://doi.org/10.1007%2FBF01491891). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [206795705](https://api.semanticscholar.org/CorpusID:206795705). "Man kann auch ganz burleske Fälle konstruieren. Eine Katze wird in eine Stahlkammer gesperrt, zusammen mit folgender Höllenmaschine (die man gegen den direkten Zugriff der Katze sichern muß): in einem Geigerschen Zählrohr befindet sich eine winzige Menge radioaktiver Substanz, so wenig, daß im Laufe einer Stunde vielleicht eines von den Atomen zerfällt, ebenso wahrscheinlich aber auch keines; geschieht es, so spricht das Zählrohr an und betätigt über ein Relais ein Hämmerchen, das ein Kölbchen mit Blausäure zertrümmert. Hat man dieses ganze System eine Stunde lang sich selbst überlassen, so wird man sich sagen, daß die Katze noch lebt, wenn inzwischen kein Atom zerfallen ist. Der erste Atomzerfall würde sie vergiftet haben. Die Psi-Funktion des ganzen Systems würde das so zum Ausdruck bringen, daß in ihr die lebende und die tote Katze (s.v.v.) \[sit venia verbo\] zu gleichen Teilen gemischt oder verschmiert sind. Das Typische an solchen Fällen ist, daß eine ursprünglich auf den Atombereich beschränkte Unbestimmtheit sich in grobsinnliche Unbestimmtheit umsetzt, die sich dann durch direkte Beobachtung entscheiden läßt. Das hindert uns, in so naiver Weise ein "verwaschenes Modell" als Abbild der Wirklichkeit gelten zu lassen. An sich enthielte es nichts Unklares oder Widerspruchsvolles. Es ist ein Unterschied zwischen einer verwackelten oder unscharf eingestellten Photographie und einer Aufnahme von Wolken und Nebelschwaden." 2. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Fine_2-0) [Fine, Arthur](https://en.wikipedia.org/wiki/Arthur_Fine "Arthur Fine"). ["The Einstein-Podolsky-Rosen Argument in Quantum Theory"](https://plato.stanford.edu/entries/qt-epr/). Stanford Encyclopedia of Philosophy. Retrieved June 11, 2020. 3. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-3) [Ball, Philip](https://en.wikipedia.org/wiki/Philip_Ball "Philip Ball") (June 25, 2018). ["Real-Life Schrödinger's Cats Probe the Boundary of the Quantum World"](https://web.archive.org/web/20250228155932/https://www.quantamagazine.org/real-life-schrodingers-cats-probe-the-boundary-of-the-quantum-world-20180625/). Quanta Magazine. Archived from [the original](https://www.quantamagazine.org/real-life-schrodingers-cats-probe-the-boundary-of-the-quantum-world-20180625/) on February 28, 2025. Retrieved February 24, 2025. 4. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-4) Einstein, A.; Podolsky, B.; Rosen, N. (May 15, 1935). "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?". Physical Review. 47 (10): 777–780\. [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/PhysRev.47.777](https://doi.org/10.1103%2FPhysRev.47.777). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0031-899X](https://search.worldcat.org/issn/0031-899X). 5. ^ [*a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-1) [c](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-2) Fine, Arthur (2017). ["The Einstein-Podolsky-Rosen Argument in Quantum Theory"](https://plato.stanford.edu/entries/qt-epr/). Stanford Encyclopedia of Philosophy. Stanford University. Retrieved April 11, 2021. 6. ^ [a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-1) [c](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-2) [d](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-3) [e](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-4) Baggott, J. E. (2013). The quantum story: a history in 40 moments* (Impression: 3 ed.). Oxford: Oxford Univ. Press. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-0-19-965597-7](https://en.wikipedia.org/wiki/Special:BookSources/978-0-19-965597-7 "Special:BookSources/978-0-19-965597-7") . 7. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Polkinghorne_7-0) Polkinghorne, J. C. (1985). [The Quantum World](https://books.google.com/books?id=lp4JPYnLrtEC&q=%22schrodinger%27s+cat%22+%22alive+dead&pg=PA67). [Princeton University Press](https://en.wikipedia.org/wiki/Princeton_University_Press "Princeton University Press"). p. 67. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [0-691-02388-3](https://en.wikipedia.org/wiki/Special:BookSources/0-691-02388-3 "Special:BookSources/0-691-02388-3") . [Archived](https://web.archive.org/web/20150519001623/https://books.google.com/books?id=lp4JPYnLrtEC&pg=PA67&dq=%22schrodinger%27s+cat%22+%22alive+dead) from the original on May 19, 2015. Retrieved November 20, 2020. 8. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Tetlow_8-0) Tetlow, Philip (2012). [Understanding Information and Computation: From Einstein to Web Science](https://books.google.com/books?id=Rk7O3EG0Xn4C&q=%22alive+and+dead%22&pg=PA321). Gower Publishing, Ltd. p. 321. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-4094-4040-6](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4094-4040-6 "Special:BookSources/978-1-4094-4040-6") . [Archived](https://web.archive.org/web/20150519001741/https://books.google.com/books?id=Rk7O3EG0Xn4C&pg=PA321&dq=%22alive+and+dead%22) from the original on May 19, 2015. 9. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-9) Lazarou, Dimitris (2007). "Interpretation of quantum theory - An overview". [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[0712\.3466](https://arxiv.org/abs/0712.3466) \[[quant-ph](https://arxiv.org/archive/quant-ph)\]. 10. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-10) Trimmer, John D. (1980). "The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper". Proceedings of the American Philosophical Society. 124 (5): 323–338\. [JSTOR](https://en.wikipedia.org/wiki/JSTOR_\(identifier\) "JSTOR (identifier)") [986572](https://www.jstor.org/stable/986572). The English translation here is based on the German original, not on the inaccurate version in this source's translation of the entire article: [Schrödinger: "The Present Situation in Quantum Mechanics." 5. Are the Variables Really Blurred?](http://web.archive.org/web/20161020061333/https://www.tuhh.de/rzt/rzt/it/QM/cat.html) 11. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-11) Maxwell, Nicholas (January 1, 1993). "Induction and Scientific Realism: Einstein versus van Fraassen Part Three: Einstein, Aim-Oriented Empiricism and the Discovery of Special and General Relativity". The British Journal for the Philosophy of Science. 44 (2): 275–305\. [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1093/bjps/44.2.275](https://doi.org/10.1093%2Fbjps%2F44.2.275). [JSTOR](https://en.wikipedia.org/wiki/JSTOR_\(identifier\) "JSTOR (identifier)") [687649](https://www.jstor.org/stable/687649). 12. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-PeresCat_12-0) [Peres, Asher](https://en.wikipedia.org/wiki/Asher_Peres "Asher Peres") (January 1988). ["Schrödinger's immortal cat"](http://link.springer.com/10.1007/BF01882873). Foundations of Physics. 18 (1): 57–76\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1988FoPh...18...57P](https://ui.adsabs.harvard.edu/abs/1988FoPh...18...57P). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1007/BF01882873](https://doi.org/10.1007%2FBF01882873). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0015-9018](https://search.worldcat.org/issn/0015-9018). 13. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-SchlosshauerDecoherenceReview_13-0) Schlosshauer, Maximilian (February 23, 2005). ["Decoherence, the measurement problem, and interpretations of quantum mechanics"](https://link.aps.org/doi/10.1103/RevModPhys.76.1267). Reviews of Modern Physics. 76 (4): 1267–1305\. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[quant-ph/0312059](https://arxiv.org/abs/quant-ph/0312059). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2004RvMP...76.1267S](https://ui.adsabs.harvard.edu/abs/2004RvMP...76.1267S). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/RevModPhys.76.1267](https://doi.org/10.1103%2FRevModPhys.76.1267). 14. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Wimmel1992_14-0) Wimmel, Hermann (1992). [Quantum physics & observed reality: a critical interpretation of quantum mechanics](https://books.google.com/books?id=-4sJ_fgyZJEC&pg=PA2). World Scientific. p. 2. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-981-02-1010-6](https://en.wikipedia.org/wiki/Special:BookSources/978-981-02-1010-6 "Special:BookSources/978-981-02-1010-6") . [Archived](https://web.archive.org/web/20130520185205/http://books.google.com/books?id=-4sJ_fgyZJEC&pg=PA2) from the original on May 20, 2013. Retrieved May 9, 2011. 15. ^ [*a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Tales_of_the_Quantum_15-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Tales_of_the_Quantum_15-1) Hobson, Art (2017). [Tales of the Quantum: Understanding Physics' Most Fundamental Theory](https://books.google.com/books?id=mGduDQAAQBAJ). New York, NY: Oxford University Press. pp. 200–202\. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-0-19-067963-7](https://en.wikipedia.org/wiki/Special:BookSources/978-0-19-067963-7 "Special:BookSources/978-0-19-067963-7") . Retrieved April 8, 2022. 16. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-16)* [Omnès, Roland](https://en.wikipedia.org/wiki/Roland_Omn%C3%A8s "Roland Omnès") (1999). [Understanding Quantum Mechanics](https://books.google.com/books?id=XET_DwAAQBAJ). Princeton, New Jersey: Princeton University Press. pp. 60–62\. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [0-691-00435-8](https://en.wikipedia.org/wiki/Special:BookSources/0-691-00435-8 "Special:BookSources/0-691-00435-8") . Retrieved April 8, 2022. 17. ^ [*a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Surfing_the_Quantum_World_17-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Surfing_the_Quantum_World_17-1) Levin, Frank S. (2017). [Surfing the Quantum World](https://books.google.com/books?id=Y1w-DwAAQBAJ). New York, NY: Oxford University Press. pp. 229–232\. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-0-19-880827-5](https://en.wikipedia.org/wiki/Special:BookSources/978-0-19-880827-5 "Special:BookSources/978-0-19-880827-5") . Retrieved April 8, 2022. 18. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-18)* Puri, Ravinder R. (2017). [Non-Relativistic Quantum Mechanics](https://books.google.com/books?id=qDbSDgAAQBAJ). Cambridge, United Kingdom: Cambridge University Press. p. 146. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-107-16436-9](https://en.wikipedia.org/wiki/Special:BookSources/978-1-107-16436-9 "Special:BookSources/978-1-107-16436-9") . Retrieved April 8, 2022. 19. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Carpenter2006_19-0) Carpenter RHS; Anderson AJ (2006). ["The death of Schrödinger's cat and of consciousness-based wave-function collapse"](https://web.archive.org/web/20061130173850/http://www.ensmp.fr/aflb/AFLB-311/aflb311m387.pdf) (PDF). [Annales de la Fondation Louis de Broglie](https://en.wikipedia.org/wiki/Annales_de_la_Fondation_Louis_de_Broglie "Annales de la Fondation Louis de Broglie"). 31 (1): 45–52\. Archived from [the original](http://www.ensmp.fr/aflb/AFLB-311/aflb311m387.pdf) (PDF) on November 30, 2006. Retrieved September 10, 2010. 20. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Okon2006_20-0) Okón E, Sebastián MA (2016). "How to Back up or Refute Quantum Theories of Consciousness". Mind and Matter. 14 (1): 25–49\. 21. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Faye2008_21-0) [Faye, J](https://en.wikipedia.org/wiki/Jan_Faye "Jan Faye") (January 24, 2008). ["Copenhagen Interpretation of Quantum Mechanics"](http://plato.stanford.edu/entries/qm-copenhagen/). [Stanford Encyclopedia of Philosophy](https://en.wikipedia.org/wiki/Stanford_Encyclopedia_of_Philosophy "Stanford Encyclopedia of Philosophy"). The Metaphysics Research Lab Center for the Study of Language and Information, [Stanford University](https://en.wikipedia.org/wiki/Stanford_University "Stanford University"). Retrieved September 19, 2010. 22. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-22) [John Bell](https://en.wikipedia.org/wiki/John_Stewart_Bell "John Stewart Bell") (1990). "Against 'measurement'". Physics World. 3 (8): 33–41\. [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1088/2058-7058/3/8/26](https://doi.org/10.1088%2F2058-7058%2F3%2F8%2F26). 23. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-23) [Niels Bohr](https://en.wikipedia.org/wiki/Niels_Bohr "Niels Bohr") (1985) \[May 16, 1947\]. Jørgen Kalckar (ed.). [Foundations of Quantum Physics I (1926-1932)](https://www.nbarchive.dk/publications/bcw/). Niels Bohr: Collected Works. Vol. 6. pp. 451–454\. 24. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-24) Stig Stenholm (1983). "To fathom space and time". In [Pierre Meystre](https://en.wikipedia.org/w/index.php?title=Pierre_Meystre&action=edit&redlink=1 "Pierre Meystre (page does not exist)") (ed.). Quantum Optics, Experimental Gravitation, and Measurement Theory. Plenum Press. p. 121. "The role of irreversibility in the theory of measurement has been emphasized by many. Only this way can a permanent record be obtained. The fact that separate pointer positions must be of the asymptotic nature usually associated with irreversibility has been utilized in the measurement theory of Daneri, Loinger and Prosperi (1962). It has been accepted as a formal representation of Bohr's ideas by Rosenfeld (1966)." 25. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-25) Haake, Fritz (April 1, 1993). "Classical motion of meter variables in the quantum theory of measurement". [Physical Review A](https://en.wikipedia.org/wiki/Physical_Review_A "Physical Review A"). 47 (4): 2506–2517\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1993PhRvA..47.2506H](https://ui.adsabs.harvard.edu/abs/1993PhRvA..47.2506H). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/PhysRevA.47.2506](https://doi.org/10.1103%2FPhysRevA.47.2506). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [9909217](https://pubmed.ncbi.nlm.nih.gov/9909217). 26. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-zurek03_26-0) [Zurek, Wojciech H.](https://en.wikipedia.org/wiki/Wojciech_H._Zurek "Wojciech H. Zurek") (2003). "Decoherence, einselection, and the quantum origins of the classical". Reviews of Modern Physics. 75 (3): 715. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[quant-ph/0105127](https://arxiv.org/abs/quant-ph/0105127). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2003RvMP...75..715Z](https://ui.adsabs.harvard.edu/abs/2003RvMP...75..715Z). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/revmodphys.75.715](https://doi.org/10.1103%2Frevmodphys.75.715). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [14759237](https://api.semanticscholar.org/CorpusID:14759237). 27. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-zurek91_27-0) [Wojciech H. Zurek](https://en.wikipedia.org/wiki/Wojciech_H._Zurek "Wojciech H. Zurek"), "Decoherence and the transition from quantum to classical", Physics Today, 44, pp. 36–44 (1991) 28. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-28) Home, D.; Whitaker, M. A. B. (1992). "Ensemble Interpretations of Quantum Mechanics: A Modern Perspective". Physics Reports. 210 (4): 223–317\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1992PhR...210..223H](https://ui.adsabs.harvard.edu/abs/1992PhR...210..223H). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1016/0370-1573(92)90088-H](https://doi.org/10.1016%2F0370-1573%2892%2990088-H). 29. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-29) [Rovelli, Carlo](https://en.wikipedia.org/wiki/Carlo_Rovelli "Carlo Rovelli") (1996). "Relational Quantum Mechanics". International Journal of Theoretical Physics. 35 (8): 1637–1678\. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[quant-ph/9609002](https://arxiv.org/abs/quant-ph/9609002). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1996IJTP...35.1637R](https://ui.adsabs.harvard.edu/abs/1996IJTP...35.1637R). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1007/BF02302261](https://doi.org/10.1007%2FBF02302261). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [16325959](https://api.semanticscholar.org/CorpusID:16325959). 30. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-30) Cramer, John G. (July 1986). ["The transactional interpretation of quantum mechanics"](https://www.researchgate.net/publication/280926546). Reviews of Modern Physics. 58 (3): 647–685\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1986RvMP...58..647C](https://ui.adsabs.harvard.edu/abs/1986RvMP...58..647C). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/RevModPhys.58.647](https://doi.org/10.1103%2FRevModPhys.58.647). 31. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-31) Okon, Elias; Sudarsky, Daniel (February 1, 2014). "Benefits of Objective Collapse Models for Cosmology and Quantum Gravity". Foundations of Physics. 44 (2): 114–143\. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[1309\.1730](https://arxiv.org/abs/1309.1730). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2014FoPh...44..114O](https://ui.adsabs.harvard.edu/abs/2014FoPh...44..114O). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1007/s10701-014-9772-6](https://doi.org/10.1007%2Fs10701-014-9772-6). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [1572-9516](https://search.worldcat.org/issn/1572-9516). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [67831520](https://api.semanticscholar.org/CorpusID:67831520). 32. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-32) Khazali, Mohammadsadegh; Lau, Hon Wai; Humeniuk, Adam; Simon, Christoph (August 11, 2016). "Large energy superpositions via Rydberg dressing". Physical Review A. 94 (2) 023408. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[1509\.01303](https://arxiv.org/abs/1509.01303). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2016PhRvA..94b3408K](https://ui.adsabs.harvard.edu/abs/2016PhRvA..94b3408K). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/physreva.94.023408](https://doi.org/10.1103%2Fphysreva.94.023408). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [2469-9926](https://search.worldcat.org/issn/2469-9926). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [118364289](https://api.semanticscholar.org/CorpusID:118364289). 33. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-33) ["What is the world's biggest Schrodinger cat?"](http://physics.stackexchange.com/questions/3309/what-is-the-worlds-biggest-schrodinger-cat). stackexchange.com. [Archived](https://web.archive.org/web/20120108000629/http://physics.stackexchange.com/questions/3309/what-is-the-worlds-biggest-schrodinger-cat) from the original on January 8, 2012. 34. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-34) ["NIST Researchers Create 'Quantum Cats' Made of Light"](https://web.archive.org/web/20170507224218/https://www.nist.gov/news-events/news/2010/08/nist-researchers-create-quantum-cats-made-light). NIST. August 31, 2010. Archived from [the original](https://www.nist.gov/news-events/news/2010/08/nist-researchers-create-quantum-cats-made-light) on May 7, 2017. 35. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-35) Sychev, Demid V.; Ulanov, Alexander E.; Pushkina, Anastasia A.; Richards, Matthew W.; Fedorov, Ilya A.; Lvovsky, Alexander I. (June 2017). ["Enlargement of optical Schrödinger's cat states"](https://www.nature.com/articles/nphoton.2017.57). Nature Photonics. 11 (6): 379–382\. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[1609\.08425](https://arxiv.org/abs/1609.08425). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2017NaPho..11..379S](https://ui.adsabs.harvard.edu/abs/2017NaPho..11..379S). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1038/nphoton.2017.57](https://doi.org/10.1038%2Fnphoton.2017.57). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [1749-4885](https://search.worldcat.org/issn/1749-4885). 36. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-36) Monroe, C.; Meekhof, D. M.; King, B. E.; Wineland, D. J. (May 24, 1996). "A "Schrödinger's cat" Superposition State of an Atom". Science. 272 (5265): 1131–1136\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1996Sci...272.1131M](https://ui.adsabs.harvard.edu/abs/1996Sci...272.1131M). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1126/science.272.5265.1131](https://doi.org/10.1126%2Fscience.272.5265.1131). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [8662445](https://pubmed.ncbi.nlm.nih.gov/8662445). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [2311821](https://api.semanticscholar.org/CorpusID:2311821). 37. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-37) ["Physics World: Schrödinger's cat comes into view"](https://physicsworld.com/a/schrodingers-cat-comes-into-view/). July 5, 2000. 38. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-38) Castelvecchi, Davide. ["Macro-Weirdness: "Quantum Microphone" Puts Naked-Eye Object in 2 Places at Once"](https://web.archive.org/web/20120319021316/http://www.scientificamerican.com/article.cfm?id=quantum-microphone). Scientific American. Archived from [the original](https://www.scientificamerican.com/article/quantum-microphone/) on March 19, 2012. 39. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-39) Romero-Isart, O.; Juan, M. L.; Quidant, R.; Cirac, J. I. (2010). "Toward Quantum Superposition of Living Organisms". New Journal of Physics. 12 (3) 033015. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[0909\.1469](https://arxiv.org/abs/0909.1469). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2010NJPh...12c3015R](https://ui.adsabs.harvard.edu/abs/2010NJPh...12c3015R). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1088/1367-2630/12/3/033015](https://doi.org/10.1088%2F1367-2630%2F12%2F3%2F033015). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [59151724](https://api.semanticscholar.org/CorpusID:59151724). 40. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-40) ["Could 'Schrödinger's bacterium' be placed in a quantum superposition?"](http://physicsworld.com/cws/article/news/2015/sep/21/could-schrodingers-bacterium-be-placed-in-a-quantum-superposition). physicsworld.com. [Archived](https://web.archive.org/web/20160730174613/http://physicsworld.com/cws/article/news/2015/sep/21/could-schrodingers-bacterium-be-placed-in-a-quantum-superposition) from the original on July 30, 2016. 41. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-LS-20191107_41-0) Najjar, Dana (November 7, 2019). ["Physicists Can Finally Peek at Schrödinger's Cat Without Killing It Forever"](https://www.livescience.com/schrodingers-cat-can-be-peeked-at.html). [Live Science](https://en.wikipedia.org/wiki/Live_Science "Live Science"). Retrieved November 7, 2019. 42. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-NJP-20191001_42-0) Patekar, Kartik; Hofmann, Holger F. (2019). ["The role of system–meter entanglement in controlling the resolution and decoherence of quantum measurements"](https://doi.org/10.1088%2F1367-2630%2Fab4451). [New Journal of Physics](https://en.wikipedia.org/wiki/New_Journal_of_Physics "New Journal of Physics"). 21 (10): 103006. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[1905\.09978](https://arxiv.org/abs/1905.09978). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2019NJPh...21j3006P](https://ui.adsabs.harvard.edu/abs/2019NJPh...21j3006P). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1088/1367-2630/ab4451](https://doi.org/10.1088%2F1367-2630%2Fab4451). 43. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-43) Crease, Robert P. (May 27, 2024). ["Ursula Le Guin: the pioneering author we should thank for popularizing Schrödinger's cat"](https://physicsworld.com/a/ursula-le-guin-the-pioneering-author-we-should-thank-for-popularizing-schrodingers-cat/). Physics World. Retrieved October 27, 2024. 44. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-100CCC_44-0) Sam Stall (May 1, 2007). [100 Cats Who Changed Civilization](https://books.google.com/books?id=coXIF8WbEKEC). Quirk Books. p. 34. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-59474-163-0](https://en.wikipedia.org/wiki/Special:BookSources/978-1-59474-163-0 "Special:BookSources/978-1-59474-163-0") . 45. ^ [*a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Crease_45-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Crease_45-1) Crease, Robert P. (2012). ["The cat that never dies"](https://doi.org/10.1088%2F2058-7058%2F25%2F04%2F27). Physics World. 25* (4): 18–19\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2012PhyW...25d..18C](https://ui.adsabs.harvard.edu/abs/2012PhyW...25d..18C). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1088/2058-7058/25/04/27](https://doi.org/10.1088%2F2058-7058%2F25%2F04%2F27). 46. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-46) Ryan, Marie-Laure (2011). ["Narrative/Science Entanglements: On the Thousand and One Literary Lives of Schrödinger's Cat"](https://www.jstor.org/stable/41289295). Narrative. 19 (2): 171–186\. [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [1063-3685](https://search.worldcat.org/issn/1063-3685). [JSTOR](https://en.wikipedia.org/wiki/JSTOR_\(identifier\) "JSTOR (identifier)") [41289295](https://www.jstor.org/stable/41289295). 47. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-47) Kravitz, Bennett (2013). ["Thoughts on the Anti-Detective in Paul Auster's "New York Trilogy", Adam Ross's "Mister Peanut", and Martha Grimes' "The Old Wine Shades""](https://www.jstor.org/stable/23610151). Studies in Popular Culture. 36 (1): 45–61\. [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0888-5753](https://search.worldcat.org/issn/0888-5753). [JSTOR](https://en.wikipedia.org/wiki/JSTOR_\(identifier\) "JSTOR (identifier)") [23610151](https://www.jstor.org/stable/23610151). 48. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-48) Branzburg, Judith V. (October 31, 2000). ["Dead cats and live bodies"](https://www.proquest.com/openview/a751e740ad411cd002452117c93b4322). The Lesbian Review of Books. 7 (1): 3. 49. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-49) ["SFE: Wilson, Robert Anton"](https://sf-encyclopedia.com/entry/wilson_robert_anton). sf-encyclopedia.com. Retrieved December 3, 2022. 50. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-50) ["SFE: Thought Experiment"](https://sf-encyclopedia.com/entry/thought_experiment). sf-encyclopedia.com. Retrieved December 3, 2022. 51. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-51) Goldberg, Matt (April 17, 2020). ["A Serious Man Ending Explained: The Crucible of American Judaism"](https://collider.com/a-serious-man-ending-explained-american-judaism/). Collider. Retrieved December 3, 2022. 52. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-52) Orr, Christopher (September 25, 2014). ["30 Years of Coens: A Serious Man"](https://web.archive.org/web/20221203220152/https://www.theatlantic.com/entertainment/archive/2014/09/30-years-of-coens-a-serious-man/380732/). [The Atlantic](https://en.wikipedia.org/wiki/The_Atlantic "The Atlantic"). Archived from [the original](https://www.theatlantic.com/entertainment/archive/2014/09/30-years-of-coens-a-serious-man/380732/) on December 3, 2022. Retrieved December 3, 2022. 53. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-53) [Ebert, Roger](https://en.wikipedia.org/wiki/Roger_Ebert "Roger Ebert") (March 4, 2013). ["The Coen Brothers and Serious Quantum Theory"](https://web.archive.org/web/20201029024134/https://www.rogerebert.com/roger-ebert/the-coen-brothers-and-serious-quantum-theory). [Chicago Sun Times](https://en.wikipedia.org/wiki/Chicago_Sun_Times "Chicago Sun Times"). Archived from [the original](https://www.rogerebert.com/roger-ebert/the-coen-brothers-and-serious-quantum-theory) on October 29, 2020. 54. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-54) Collis, Clark (June 20, 2014). ["Coherence"](https://web.archive.org/web/20221203220151/https://ew.com/article/2014/06/20/coherence/). Entertainment Weekly. Archived from [the original](https://ew.com/article/2014/06/20/coherence/) on December 3, 2022. Retrieved December 3, 2022. 55. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-55) Landsman, Peggy (April 1, 2022). [""Schrodinger's Cat""](https://web.archive.org/web/20220529020959/https://www.scientificamerican.com/article/poem-schroedingers-cat/). Scientific American. Archived from [the original](https://www.scientificamerican.com/article/poem-schroedingers-cat/) on May 29, 2022. Retrieved February 22, 2023. 56. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-56) Robbins, Hollis. [""His Paws Upon The Dish""](http://www.percontra.net/issues/34/poetry/his-paws-upon-the/). Per Contra Journal. Per Contra. Retrieved February 22, 2023. 57. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger's_Girlfriend_57-0) Ehren, Christine (November 18, 2001). ["World Premiere Schrodinger's Girlfriend Closes Nov. 18 at San Fran's Magic"](https://web.archive.org/web/20100517085507/http://www.playbill.com/news/article/63363-World-Premiere-Schrodingers-Girlfriend-Closes-Nov-18-at-San-Frans-Magic). Schrodingers Girlfriend. Playbill Review. Archived from [the original](http://www.playbill.com/news/article/63363-World-Premiere-Schrodingers-Girlfriend-Closes-Nov-18-at-San-Frans-Magic) on May 17, 2010. Retrieved January 6, 2015. 58. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodingers_Girlfriend_SFG_58-0) Hurwitt, Robert (November 5, 2001). ["'Girlfriend' runs out of inspiration / Ideas bog down physics comedy"](https://web.archive.org/web/20151126043542/http://www.sfgate.com/entertainment/article/Girlfriend-runs-out-of-inspiration-Ideas-bog-2862061.php). SFGate Review. Archived from [the original](http://www.sfgate.com/entertainment/article/Girlfriend-runs-out-of-inspiration-Ideas-bog-2862061.php) on November 26, 2015. Retrieved December 5, 2015. 59. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-59) Mohan, Geoffrey (August 12, 2013). ["Google doodle honors physicist Erwin Schrodinger and his cat"](https://web.archive.org/web/20221202232119/https://www.baltimoresun.com/la-sci-sn-schrodinger-cat-20130812-story.html). Baltimore Sun. Archived from [the original](https://www.baltimoresun.com/la-sci-sn-schrodinger-cat-20130812-story.html) on December 2, 2022. Retrieved December 2, 2022. 60. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-The_Age_60-0) Farrer, Gordon (January 6, 2006). ["Sum thing to do with maths genius"](https://web.archive.org/web/20080115093824/http://www.theage.com.au/news/tv--radio/sum-thing-to-do-with-maths-genius/2006/01/05/1136387564868.html). The Age. Melbourne. Archived from [the original](http://www.theage.com.au/news/tv--radio/sum-thing-to-do-with-maths-genius/2006/01/05/1136387564868.html) on January 15, 2008. Retrieved August 28, 2007. 61. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-61) [Singh, Simon](https://en.wikipedia.org/wiki/Simon_Singh "Simon Singh") (October 2014). ["Theories of quantum levity"](https://iopscience.iop.org/article/10.1088/2058-7058/27/10/41). Physics World. 27 (10): 80. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2014PhyW...27j..80S](https://ui.adsabs.harvard.edu/abs/2014PhyW...27j..80S). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1088/2058-7058/27/10/41](https://doi.org/10.1088%2F2058-7058%2F27%2F10%2F41). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0953-8585](https://search.worldcat.org/issn/0953-8585). 62. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-62) ["The Famous Schrodinger's Cat Thought Experiment Gets Brought to Life in an Off-Kilter Animation"](https://web.archive.org/web/20221202230558/https://www.openculture.com/2017/03/the-famous-schrodingers-cat-thought-experiment-gets-brought-to-life-in-an-off-kilter-animation.html). Open Culture. March 24, 2017. Archived from [the original](https://www.openculture.com/2017/03/the-famous-schrodingers-cat-thought-experiment-gets-brought-to-life-in-an-off-kilter-animation.html) on December 2, 2022. Retrieved December 2, 2022. 63. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-63) ["NIGHTMARE シュレーディンガーナイフ歌詞 – 歌詞探索【歌詞リリ】"](https://web.archive.org/web/20230528210243/https://www.lyrical-nonsense.com/lyrics/nightmare/shrodinger-knife/). Lyrical Nonsense. Archived from [the original](https://www.lyrical-nonsense.com/lyrics/nightmare/shrodinger-knife/) on May 28, 2023. Retrieved May 28, 2023. ## Further reading - [Einstein, Albert](https://en.wikipedia.org/wiki/Albert_Einstein "Albert Einstein"); [Podolsky, Boris](https://en.wikipedia.org/wiki/Boris_Podolsky "Boris Podolsky"); [Rosen, Nathan](https://en.wikipedia.org/wiki/Nathan_Rosen "Nathan Rosen") (May 15, 1935). ["Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?"](https://doi.org/10.1103%2FPhysRev.47.777). Physical Review. 47 (10): 777–780\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1935PhRv...47..777E](https://ui.adsabs.harvard.edu/abs/1935PhRv...47..777E). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/PhysRev.47.777](https://doi.org/10.1103%2FPhysRev.47.777). - Leggett, Tony (August 2000). ["New Life for Schrödinger's Cat"](https://jrfriedman.people.amherst.edu/Leggett%20Physics%20World%20article/PW%20article.pdf) (PDF). Physics World. pp. 23–24. Retrieved February 28, 2020. An article on experiments with "cat state" superpositions in superconducting rings, in which the electrons go around the ring in two directions simultaneously. - Trimmer, John D. (1980). "The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper". [Proceedings of the American Philosophical Society](https://en.wikipedia.org/wiki/Proceedings_of_the_American_Philosophical_Society "Proceedings of the American Philosophical Society"). 124 (5): 323–338\. [JSTOR](https://en.wikipedia.org/wiki/JSTOR_\(identifier\) "JSTOR (identifier)") [986572](https://www.jstor.org/stable/986572). ([registration required](https://en.wikipedia.org/wiki/Wikipedia:Verifiability#Access_to_sources "Wikipedia:Verifiability")) - Yam, Phillip (October 9, 2012). ["Bringing Schrödinger's Cat to Life"](https://www.scientificamerican.com/article/bringing-schrodingers-quantum-cat-to-life/). Scientific American. Retrieved February 28, 2020. A description of investigations of quantum "cat states" and wave function collapse by [Serge Haroche](https://en.wikipedia.org/wiki/Serge_Haroche "Serge Haroche") and [David J. Wineland](https://en.wikipedia.org/wiki/David_J._Wineland "David J. Wineland"), for which they won the 2012 [Nobel Prize in Physics](https://en.wikipedia.org/wiki/List_of_Nobel_laureates_in_Physics "List of Nobel laureates in Physics"). - Violaris, M. (2023). A Physics Lab Inside Your Head: Quantum Thought Experiments as an Educational Tool. 2023 IEEE International Conference on Quantum Computing and Engineering (QCE). Bellevue, WA, USA. pp. 58–67\. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[2312\.07840](https://arxiv.org/abs/2312.07840). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1109/QCE57702.2023.20325](https://doi.org/10.1109%2FQCE57702.2023.20325). Reduction of the Schrödinger's cat to a simple [quantum circuit](https://en.wikipedia.org/wiki/Quantum_circuit "Quantum circuit"). ## External links [![Wikimedia Commons logo](https://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/40px-Commons-logo.svg.png)](https://en.wikipedia.org/wiki/File:Commons-logo.svg) Wikimedia Commons has media related to [Schrödinger's Cat](https://commons.wikimedia.org/wiki/Category:Schr%C3%B6dinger%27s_Cat "commons:Category:Schrödinger's Cat"). - [A spoken word version](https://en.wikipedia.org/wiki/File:Schrodingers-cat.ogg "File:Schrodingers-cat.ogg") of this article (created from a revision of the article dated 2013-08-12). - [Schrödinger's Cat](http://www.informationphilosopher.com/solutions/experiments/schrodingerscat/) from the Information Philosopher. - [Schrödinger's Cat - Sixty Symbols](http://www.sixtysymbols.com/videos/schrodinger.htm) - a video published by the [University of 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communication") [Quantum cryptography](https://en.wikipedia.org/wiki/Quantum_cryptography "Quantum cryptography") [Quantum electronics](https://en.wikipedia.org/wiki/Quantum_optics#Quantum_electronics "Quantum optics") [Quantum error correction](https://en.wikipedia.org/wiki/Quantum_error_correction "Quantum error correction") [Quantum imaging](https://en.wikipedia.org/wiki/Quantum_imaging "Quantum imaging") [Quantum image processing](https://en.wikipedia.org/wiki/Quantum_image_processing "Quantum image processing") [Quantum information](https://en.wikipedia.org/wiki/Quantum_information "Quantum information") [Quantum key distribution](https://en.wikipedia.org/wiki/Quantum_key_distribution "Quantum key distribution") [Quantum logic](https://en.wikipedia.org/wiki/Quantum_logic "Quantum logic") [Quantum logic gates](https://en.wikipedia.org/wiki/Quantum_logic_gate "Quantum logic gate") [Quantum machine](https://en.wikipedia.org/wiki/Quantum_machine "Quantum machine") [Quantum machine 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Readable Markdown	[![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/91/Schrodingers_cat.svg/500px-Schrodingers_cat.svg.png)](https://en.wikipedia.org/wiki/File:Schrodingers_cat.svg) Schrödinger's cat: a cat, a flask of poison, and a [radioactive](https://en.wikipedia.org/wiki/Radioactive "Radioactive") source connected to a [Geiger counter](https://en.wikipedia.org/wiki/Geiger_counter "Geiger counter") are placed in a sealed box. As illustrated, the quantum description uses a superposition of an alive cat and one that has died. In [quantum mechanics](https://en.wikipedia.org/wiki/Quantum_mechanics "Quantum mechanics"), Schrödinger's cat is a [thought experiment](https://en.wikipedia.org/wiki/Thought_experiment "Thought experiment") concerning [quantum superposition](https://en.wikipedia.org/wiki/Quantum_superposition "Quantum superposition"). In the thought experiment, a hypothetical [cat](https://en.wikipedia.org/wiki/Cat "Cat") in a closed box may be considered to be simultaneously both alive and dead while it is unobserved, as a result of its fate being linked to a random [subatomic](https://en.wikipedia.org/wiki/Subatomic_particle "Subatomic particle") event that may or may not occur. This experiment, viewed this way, is described as a [paradox](https://en.wikipedia.org/wiki/Paradox "Paradox"). This thought experiment was devised by physicist [Erwin Schrödinger](https://en.wikipedia.org/wiki/Erwin_Schr%C3%B6dinger "Erwin Schrödinger") in 1935,[\[1\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1) in a discussion with [Albert Einstein](https://en.wikipedia.org/wiki/Albert_Einstein "Albert Einstein"),[\[2\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Fine-2) to illustrate what Schrödinger saw as the problems of [Niels Bohr](https://en.wikipedia.org/wiki/Niels_Bohr "Niels Bohr") and [Werner Heisenberg](https://en.wikipedia.org/wiki/Werner_Heisenberg "Werner Heisenberg")'s philosophical views on quantum mechanics. In Schrödinger's original formulation, a cat, a flask of poison, and a [radioactive](https://en.wikipedia.org/wiki/Radioactive "Radioactive") source are placed in a sealed box. If an internal radiation monitor such as a [Geiger counter](https://en.wikipedia.org/wiki/Geiger_counter "Geiger counter") detects radioactivity (a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. If no decaying atom triggers the monitor, the cat remains alive. Mathematically, the [wave function](https://en.wikipedia.org/wiki/Wave_function "Wave function") that describes the contents of the box is a combination, or [quantum superposition](https://en.wikipedia.org/wiki/Quantum_superposition "Quantum superposition"), of these two possibilities. Yet, when one looks in the box, one sees the cat either alive or dead, not both alive and dead. This poses the question of when exactly quantum superposition ends and reality resolves into one possibility or the other. Although originally a critique of Bohr and Heisenberg, Schrödinger's seemingly paradoxical thought experiment became part of the foundation of quantum mechanics. It is often featured in theoretical discussions of the [interpretations of quantum mechanics](https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics "Interpretations of quantum mechanics"), particularly in situations involving the [measurement problem](https://en.wikipedia.org/wiki/Measurement_problem "Measurement problem"). As a result, Schrödinger's cat has had enduring [appeal in popular culture](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat_in_popular_culture "Schrödinger's cat in popular culture"). The experiment is not intended to be actually performed on a cat, but rather as an easily understandable illustration of the behavior of atoms. Experiments at the atomic scale have been carried out, showing that very small objects may exist as superpositions, but superposing an object as large as a cat would pose considerable technical difficulties.[\[3\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-3) Fundamentally, the Schrödinger's cat experiment asks how long quantum superpositions last and when (or whether) they collapse. Different [interpretations of the mathematics of quantum mechanics](https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics "Interpretations of quantum mechanics") have been proposed that give different explanations for this process. Origin and motivation Unsolved problem in physics How does the quantum description of reality, which includes elements such as the superposition of states and wavefunction collapse or quantum decoherence, give rise to the reality we perceive? Another way of stating this question regards the measurement problem: What constitutes a "measurement" that apparently causes the wave function to collapse into a definite state? Schrödinger intended his thought experiment as a discussion of the [EPR article](https://en.wikipedia.org/wiki/Einstein%E2%80%93Podolsky%E2%80%93Rosen_paradox "Einstein–Podolsky–Rosen paradox")—named after its authors [Einstein](https://en.wikipedia.org/wiki/Albert_Einstein "Albert Einstein"), [Podolsky](https://en.wikipedia.org/wiki/Boris_Podolsky "Boris Podolsky"), and [Rosen](https://en.wikipedia.org/wiki/Nathan_Rosen "Nathan Rosen")—in 1935.[\[4\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-4)[\[5\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5) The EPR article highlighted the counterintuitive nature of [quantum superpositions](https://en.wikipedia.org/wiki/Quantum_superposition "Quantum superposition"), in which a quantum system for two particles does not separate[\[6\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 150 even when the particles are detected far from their last point of contact. The EPR paper concludes with a claim that this lack of separability meant that quantum mechanics as a theory of reality was incomplete. Schrödinger and Einstein exchanged letters about Einstein's EPR article, in the course of which Einstein pointed out that the state of an [unstable](https://en.wikipedia.org/wiki/Unstable "Unstable") keg of [gunpowder](https://en.wikipedia.org/wiki/Gunpowder "Gunpowder") will, after a while, contain a superposition of both exploded and unexploded states.[\[5\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5) To further illustrate, Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a closed steel chamber, wherein the cat's life or death depended on the state of a [radioactive](https://en.wikipedia.org/wiki/Radioactive "Radioactive") atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the position taken by Bohr and Heisenberg would be that the cat remains both alive and dead until the state has been observed. Schrödinger did not wish to promote the idea of dead-and-live cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics,[\[1\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1) thus employing [reductio ad absurdum](https://en.wikipedia.org/wiki/Reductio_ad_absurdum "Reductio ad absurdum"). Since Schrödinger's time, various [interpretations of the mathematics of quantum mechanics](https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics "Interpretations of quantum mechanics") have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real, while others do not.[\[7\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Polkinghorne-7)[\[8\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Tetlow-8) Intended as a critique of ideas prevalent in 1935, the Schrödinger's cat thought experiment remains a [touchstone](https://en.wikipedia.org/wiki/Touchstone_\(metaphor\) "Touchstone (metaphor)") for modern interpretations of quantum mechanics and can be used to illustrate and compare their strengths and weaknesses.[\[9\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-9)\[[better source needed](https://en.wikipedia.org/wiki/Wikipedia:Verifiability#Questionable_sources "Wikipedia:Verifiability")\] Thought experiment [![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5e/Schroedinger_cat.jpg/330px-Schroedinger_cat.jpg)](https://en.wikipedia.org/wiki/File:Schroedinger_cat.jpg) A life-size cat figure in the garden of Huttenstrasse 9, Zurich, where [Erwin Schrödinger](https://en.wikipedia.org/wiki/Erwin_Schr%C3%B6dinger "Erwin Schrödinger") lived from 1921 to 1926. Depending on the light conditions, the figure appears to be either a live cat or a dead one. Schrödinger wrote:[\[1\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger1935-1)[\[10\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-10) > One can contrive even completely burlesque \[farcical\] cases. A cat is put in a steel chamber along with the following infernal device (which must be secured against direct interference by the cat): in a [Geiger counter](https://en.wikipedia.org/wiki/Geiger_counter "Geiger counter"), there is a tiny amount of radioactive substance, so tiny that in the course of an hour one of the atoms will perhaps decay, but also, with equal probability, that none of them will; if it does happen, the counter tube will discharge and through a relay release a hammer that will shatter a small flask of [hydrocyanic acid](https://en.wikipedia.org/wiki/Hydrocyanic_acid "Hydrocyanic acid"). If one has left this entire system to itself for an hour, one would tell oneself that the cat is still alive if no atom has [decayed](https://en.wikipedia.org/wiki/Radioactive_decay "Radioactive decay") in the meantime. Even a single atomic decay would have poisoned it. The [psi-function](https://en.wikipedia.org/wiki/Wave_function "Wave function") of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or spread out in equal parts. > > It is typical of these cases that an indeterminacy originally restricted to the atomic domain turns into a sensually observable \[macroscopic\] indeterminacy, which can then be resolved by direct observation. This prevents us from so naïvely accepting a "blurred model" as representative of reality. Per se, it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks. Schrödinger developed his famous [thought experiment](https://en.wikipedia.org/wiki/Thought_experiment "Thought experiment") in correspondence with Einstein. He suggested this 'quite ridiculous case' to illustrate his conclusion that the wave function cannot represent reality.[\[6\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 153 The wave function description of the complete cat system implies that the reality of the cat mixes the living and dead cat.[\[6\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 154 Einstein was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote:[\[6\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 157 > You are the only contemporary physicist, besides [Laue](https://en.wikipedia.org/wiki/Max_von_Laue "Max von Laue"), who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gun powder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation.[\[11\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-11) Note that the charge of gunpowder is not mentioned in Schrödinger's setup, which uses a Geiger counter as an amplifier and hydrocyanic poison instead of gunpowder. The gunpowder had been mentioned in Einstein's original suggestion to Schrödinger 15 years before, and Einstein carried it forward to the present discussion.[\[5\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Stanford1-5) Analysis In modern terms Schrödinger's hypothetical cat experiment describes the [measurement problem](https://en.wikipedia.org/wiki/Measurement_problem "Measurement problem"): quantum theory describes the cat system as a combination of two possible outcomes but only one outcome is ever observed.[\[12\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-PeresCat-12): 57 [\[13\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-SchlosshauerDecoherenceReview-13): 1269 The experiment poses the question, "when does a quantum system stop existing as a superposition of states and become one or the other?" (More technically, when does the actual quantum state stop being a non-trivial [linear combination](https://en.wikipedia.org/wiki/Linear_combination "Linear combination") of states, each of which resembles different classical states, and instead begin to have a unique classical description?) Standard microscopic quantum mechanics describes multiple possible outcomes of experiments but only one outcome is observed. The thought experiment illustrates this apparent paradox. Our intuition says that the cat cannot be in more than one state simultaneously—yet the quantum mechanical description of the thought experiment requires such a condition. Interpretations Since Schrödinger's time, other interpretations of quantum mechanics have been proposed that give different answers to the questions posed by Schrödinger's cat of how long superpositions last and when (or whether) they collapse. Copenhagen interpretation A commonly held interpretation of quantum mechanics is the Copenhagen interpretation.[\[14\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Wimmel1992-14) In the Copenhagen interpretation, a measurement results in only one state of a superposition. This thought experiment makes apparent the fact that this interpretation simply provides no explanation for the state of the cat while the box is closed. The wavefunction description of the system consists of a superposition of the states "decayed nucleus/dead cat" and "undecayed nucleus/living cat". Only when the box is opened and observed can we make a statement about the cat.[\[6\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-BaggottStory-6): 157 Role of consciousness In 1932, [John von Neumann](https://en.wikipedia.org/wiki/John_von_Neumann "John von Neumann") described in his book [Mathematical Foundations of Quantum Mechanics](https://en.wikipedia.org/wiki/Mathematical_Foundations_of_Quantum_Mechanics "Mathematical Foundations of Quantum Mechanics") a pattern where the radioactive source is observed by a device, which itself is observed by another device and so on. It makes no difference in the predictions of quantum theory where along this chain of causal effects the superposition collapses.[\[15\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Tales_of_the_Quantum-15) This potentially infinite chain could be broken if the last device is replaced by a conscious observer. This solved the problem because it was claimed that an individual's consciousness cannot be multiple.[\[16\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-16) Eugene Wigner asserted that an observer is necessary for a collapse to one or the other (e.g., either a live cat or a dead cat) of the terms on the right-hand side of a [wave function](https://en.wikipedia.org/wiki/Wave_function "Wave function"). Wigner discussed the interpretation in a thought experiment known as [Wigner's friend](https://en.wikipedia.org/wiki/Wigner%27s_friend "Wigner's friend").[\[17\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Surfing_the_Quantum_World-17) Wigner supposed that a friend opened the box and observed the cat without telling anyone. From Wigner's conscious perspective, the friend is now part of the wave function and has seen a live cat and seen a dead cat. To a third person's conscious perspective, Wigner himself becomes part of the wave function once Wigner learns the outcome from the friend. This could be extended indefinitely.[\[17\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Surfing_the_Quantum_World-17) A resolution of the paradox is that the triggering of the Geiger counter counts as a measurement of the state of the radioactive substance. Because a measurement has already occurred deciding the state of the cat, the subsequent observation by a human records only what has already occurred.[\[18\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-18) Analysis of an actual experiment by [Roger Carpenter](https://en.wikipedia.org/wiki/Roger_Carpenter "Roger Carpenter") and A. J. Anderson found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before any human knows of the result.[\[19\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Carpenter2006-19) The apparatus indicates one of two colors depending on the outcome. The human observer sees which color is indicated, but does not consciously know which outcome the color represents. A second human, the one who set up the apparatus, is told of the color and becomes conscious of the outcome, and the box is opened to check if the outcome matches.[\[15\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Tales_of_the_Quantum-15) However, it is disputed whether merely observing the color counts as a conscious observation of the outcome.[\[20\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Okon2006-20) Bohr's interpretation Analysis of the work of [Niels Bohr](https://en.wikipedia.org/wiki/Niels_Bohr "Niels Bohr"), one of the main scientists associated with the Copenhagen interpretation, suggests he viewed the state of the cat before the box is opened as indeterminate. The superposition itself had no physical meaning to Bohr: Schrödinger's cat would be either dead or alive long before the box is opened but the cat and box form an inseparable combination.[\[21\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Faye2008-21) Bohr saw no role for a human observer.[\[22\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-22): 35 Bohr emphasized the classical nature of measurement results. An "irreversible" or effectively irreversible process imparts the classical behavior of "observation" or "measurement".[\[23\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-23)[\[24\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-24)[\[25\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-25) Many-worlds interpretation [![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Schroedingers_cat_film.svg/250px-Schroedingers_cat_film.svg.png)](https://en.wikipedia.org/wiki/File:Schroedingers_cat_film.svg) The quantum-mechanical "Schrödinger's cat" paradox according to the many-worlds interpretation. In this interpretation, every event is a branch point. The cat is both alive and dead—regardless of whether the box is opened—but the "alive" and "dead" cats are in different branches of the universe that are equally real but cannot interact with each other. In 1957, [Hugh Everett](https://en.wikipedia.org/wiki/Hugh_Everett "Hugh Everett") formulated the many-worlds interpretation of quantum mechanics, which does not single out observation as a special process. In the many-worlds interpretation, both alive and dead states of the cat persist after the box is opened, but are [decoherent](https://en.wikipedia.org/wiki/Quantum_decoherence "Quantum decoherence") from each other. In other words, when the box is opened, the observer and the possibly-dead cat split into an observer looking at a box with a dead cat and an observer looking at a box with a live cat. But since the dead and alive states are decoherent, there is no communication or interaction between them. When opening the box, the observer becomes entangled with the cat, so "observer states" corresponding to the cat's being alive and dead are formed; each observer state is [entangled](https://en.wikipedia.org/wiki/Quantum_entanglement "Quantum entanglement"), or linked, with the cat so that the observation of the cat's state and the cat's state correspond with each other. Quantum decoherence ensures that the different outcomes have no interaction with each other. Decoherence is generally considered to prevent simultaneous observation of multiple states.[\[26\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-zurek03-26)[\[27\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-zurek91-27) A variant of the Schrödinger's cat experiment, known as the [quantum suicide](https://en.wikipedia.org/wiki/Quantum_suicide_and_immortality "Quantum suicide and immortality") machine, has been proposed by cosmologist [Max Tegmark](https://en.wikipedia.org/wiki/Max_Tegmark "Max Tegmark"). It examines the Schrödinger's cat experiment from the point of view of the cat, and argues that by using this approach, one may be able to distinguish between the Copenhagen interpretation and many-worlds.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Ensemble interpretation In [Ensemble interpretations](https://en.wikipedia.org/wiki/Ensemble_interpretation "Ensemble interpretation"), superpositions are sub-ensembles of a larger statistical ensemble. The state vector would not apply to individual cat experiments, but only to the statistics of many similarly prepared cat experiments. Proponents of these interpretations argue that this makes the Schrödinger's cat paradox a trivial matter, or a non-issue. When the physicist opens the box, they simply discover which subensemble that specific cat belonged to.[\[28\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-28) Relational interpretation The [relational interpretation](https://en.wikipedia.org/wiki/Relational_quantum_mechanics "Relational quantum mechanics") makes no fundamental distinction between the human experimenter, the cat, and the apparatus or between animate and inanimate systems; all are quantum systems governed by the same rules of wavefunction [evolution](https://en.wikipedia.org/wiki/Time_evolution "Time evolution"), and all may be considered "observers". But the relational interpretation allows that different observers can give different accounts of the same series of events, depending on the information they have about the system.[\[29\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-29)\[[non-primary source needed](https://en.wikipedia.org/wiki/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources "Wikipedia:No original research")\] The cat can be considered an observer of the apparatus; meanwhile, the experimenter can be considered another observer of the system in the box (the cat plus the apparatus). Before the box is opened, the cat, by nature of its being alive or dead, has information about the state of the apparatus (the atom has either decayed or not decayed); but the experimenter does not have information about the state of the box contents. In this way, the two observers simultaneously have different accounts of the situation: To the cat, the wavefunction of the apparatus has appeared to "collapse"; to the experimenter, the contents of the box appear to be in superposition. Not until the box is opened, and both observers have the same information about what happened, do both system states appear to "collapse" into the same definite result, a cat that is either alive or dead.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Transactional interpretation In the [transactional interpretation](https://en.wikipedia.org/wiki/Transactional_interpretation "Transactional interpretation") the apparatus emits an advanced wave backward in time, which combined with the wave that the source emits forward in time, forms a standing wave. The waves are seen as physically real, and the apparatus is considered an "observer". In the transactional interpretation, the collapse of the wavefunction is "atemporal" and occurs along the whole transaction between the source and the apparatus. The cat is never in superposition. Rather the cat is only in one state at any particular time, regardless of when the human experimenter looks in the box. The transactional interpretation resolves this quantum paradox.[\[30\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-30)\[[non-primary source needed](https://en.wikipedia.org/wiki/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources "Wikipedia:No original research")\] Objective collapse theories According to [objective collapse theories](https://en.wikipedia.org/wiki/Objective-collapse_theory "Objective-collapse theory"), superpositions are destroyed spontaneously (irrespective of external observation) when some objective physical threshold (of time, mass, temperature, [irreversibility](https://en.wikipedia.org/wiki/Irreversibility "Irreversibility"), etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is opened. This could loosely be phrased as "the cat observes itself" or "the environment observes the cat". Objective collapse theories require a modification of standard quantum mechanics to allow superpositions to be destroyed by the process of time evolution.[\[31\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-31) These theories could ideally be tested by creating mesoscopic superposition states in the experiment. For instance, energy cat states have been proposed as a precise detector of the quantum gravity related energy decoherence models.[\[32\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-32) Applications and tests Schrödinger's cat quantum superposition of states and effect of the environment through decoherence The experiment as described is a purely theoretical one, and the machine proposed is not known to have been constructed. However, successful experiments involving similar principles, e.g. superpositions of [relatively large](https://en.wikipedia.org/wiki/Mesoscopic "Mesoscopic") (by the standards of quantum physics) objects have been performed.[\[33\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-33)\[[better source needed](https://en.wikipedia.org/wiki/Wikipedia:Verifiability#Questionable_sources "Wikipedia:Verifiability")\] These experiments do not show that a cat-sized object can be superposed, but the known upper limit on "[cat states](https://en.wikipedia.org/wiki/Cat_state "Cat state")" has been pushed upwards by them. In many cases the state is short-lived, even when cooled to near [absolute zero](https://en.wikipedia.org/wiki/Absolute_zero "Absolute zero"). - A "cat state" has been achieved with photons.[\[34\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-34)[\[35\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-35) - A beryllium ion has been trapped in a superposed state.[\[36\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-36) - An experiment involving a [superconducting quantum interference device](https://en.wikipedia.org/wiki/Superconducting_quantum_interference_device "Superconducting quantum interference device") ("SQUID") has been linked to the theme of the thought experiment: "The superposition state does not correspond to a billion electrons flowing one way and a billion others flowing the other way. Superconducting electrons move en masse. All the superconducting electrons in the SQUID flow both ways around the loop at once when they are in the Schrödinger's cat state."[\[37\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-37) - A [piezoelectric](https://en.wikipedia.org/wiki/Piezoelectric "Piezoelectric") "tuning fork" has been constructed, which can be placed into a superposition of vibrating and non vibrating states. The resonator comprises about 10 trillion atoms.[\[38\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-38) - An experiment involving a flu virus has been proposed.[\[39\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-39) - An experiment involving a bacterium and an electromechanical oscillator has been proposed.[\[40\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-40) In [quantum computing](https://en.wikipedia.org/wiki/Quantum_computing "Quantum computing") the phrase "cat state" sometimes refers to the [GHZ state](https://en.wikipedia.org/wiki/Greenberger%E2%80%93Horne%E2%80%93Zeilinger_state "Greenberger–Horne–Zeilinger state"), wherein several qubits are in an equal superposition of all being 0 and all being 1; e.g., ![{\\displaystyle \\|\\psi \\rangle ={\\frac {1}{\\sqrt {2}}}{\\bigg (}\\|00\\ldots 0\\rangle +\\|11\\ldots 1\\rangle {\\bigg )}.}](https://wikimedia.org/api/rest_v1/media/math/render/svg/26aac0fa72a1f19180f6d2914259cadd8f07be74) According to at least one proposal, it may be possible to determine the state of the cat before observing it.[\[41\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-LS-20191107-41)[\[42\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-NJP-20191001-42) In popular culture [![](https://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/SchroCat.jpg/250px-SchroCat.jpg)](https://en.wikipedia.org/wiki/File:SchroCat.jpg) This drawing by [F. Gwynplaine MacIntyre](https://en.wikipedia.org/wiki/F._Gwynplaine_MacIntyre "F. Gwynplaine MacIntyre"), originally published in [Analog](https://en.wikipedia.org/wiki/Analog_Science_Fiction_and_Fact "Analog Science Fiction and Fact") magazine, illustrates MacIntyre's science-fiction story "Schrödinger's Cat-Sitter". The cat is depicted simultaneously in front of and behind the [impossible trident](https://en.wikipedia.org/wiki/Impossible_trident "Impossible trident") in an [optical illusion](https://en.wikipedia.org/wiki/Optical_illusion "Optical illusion"). According to historian of science [Robert P. Crease](https://en.wikipedia.org/wiki/Robert_P._Crease "Robert P. Crease"), Schrödinger's thought experiment did not become widely known until the 1970s. In 1972 [Ursula K. Le Guin](https://en.wikipedia.org/wiki/Ursula_K._Le_Guin "Ursula K. Le Guin") learned about it while researching quantum mechanics for her novel [The Dispossessed](https://en.wikipedia.org/wiki/The_Dispossessed "The Dispossessed"); Crease credits her 1974 short story "Schrödinger's Cat" with bringing the concept into popular culture.[\[43\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-43) Other [science-fiction](https://en.wikipedia.org/wiki/Science_fiction "Science fiction") writers soon picked it up, often using it in a humorous vein.[\[44\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-100CCC-44) Works of fiction have employed Schrödinger's thought experiment as plot device and as [metaphor](https://en.wikipedia.org/wiki/Metaphor "Metaphor"), in genres from [apocalyptic science fiction](https://en.wikipedia.org/wiki/Apocalyptic_science_fiction "Apocalyptic science fiction") to young-adult drama, making the cat more prominent in popular culture than in physics itself.[\[45\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Crease-45)[\[46\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-46)[\[47\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-47)[\[48\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-48) Schrödinger's cat has been a motive in many science fiction works, and used as a title of a number of them, including [Greg Bear](https://en.wikipedia.org/wiki/Greg_Bear "Greg Bear")'s "Schrödinger's Plague" ([Analog](https://en.wikipedia.org/wiki/Analog_Science_Fiction_and_Fact "Analog Science Fiction and Fact"), 29 March 1982), [George Alec Effinger](https://en.wikipedia.org/wiki/George_Alec_Effinger "George Alec Effinger")'s "[Schrödinger's Kitten](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_Kitten "Schrödinger's Kitten")" ([Omni](https://en.wikipedia.org/wiki/Omni_\(magazine\) "Omni (magazine)"), September 1988), [F. Gwynplaine MacIntyre](https://en.wikipedia.org/wiki/F._Gwynplaine_MacIntyre "F. Gwynplaine MacIntyre")'s "Schrödinger's Cat-Sitter" (Analog, July/August 2001), [Rudy Rucker](https://en.wikipedia.org/wiki/Rudy_Rucker "Rudy Rucker")'s "Schrödinger's Cat" (Analog, 30 March 1981), and [Robert Anton Wilson](https://en.wikipedia.org/wiki/Robert_Anton_Wilson "Robert Anton Wilson")'s [Schrödinger's Cat Trilogy](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_Cat_Trilogy "Schrödinger's Cat Trilogy") (1988), illustrating various [interpretations of quantum physics](https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics "Interpretations of quantum mechanics").[\[49\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-49)[\[50\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-50) In addition to novels and short stories, Schrödinger's cat has appeared in film,[\[51\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-51)[\[52\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-52)[\[53\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-53)[\[54\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-54) poetry,[\[55\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-55)[\[56\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-56) theatre,[\[57\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Schrodinger's_Girlfriend-57)[\[58\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Schrodingers_Girlfriend_SFG-58) live-action television,[\[59\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-59) cartoons,[\[60\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-The_Age-60)[\[61\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-61)[\[62\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-62) music,[\[63\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-63) and webcomics.[\[45\]](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_note-Crease-45) See also - [Basis function](https://en.wikipedia.org/wiki/Basis_function "Basis function") - [Cat state](https://en.wikipedia.org/wiki/Cat_state "Cat state") - [Complementarity (physics)](https://en.wikipedia.org/wiki/Complementarity_\(physics\) "Complementarity (physics)") - [Double-slit experiment](https://en.wikipedia.org/wiki/Double-slit_experiment "Double-slit experiment") - [Elitzur–Vaidman bomb tester](https://en.wikipedia.org/wiki/Elitzur%E2%80%93Vaidman_bomb_tester "Elitzur–Vaidman bomb tester") - [Heisenberg cut](https://en.wikipedia.org/wiki/Heisenberg_cut "Heisenberg cut") - [Modal realism](https://en.wikipedia.org/wiki/Modal_realism "Modal realism") - [Observer effect (physics)](https://en.wikipedia.org/wiki/Observer_effect_\(physics\) "Observer effect (physics)") - [Ray cat](https://en.wikipedia.org/wiki/Ray_cat "Ray cat") - [Schroedinbug](https://en.wikipedia.org/wiki/Schroedinbug "Schroedinbug") References 1. ^ [*a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-1) [c](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger1935_1-2) [Schrödinger, Erwin](https://en.wikipedia.org/wiki/Erwin_Schr%C3%B6dinger "Erwin Schrödinger") (November 1935). "Die gegenwärtige Situation in der Quantenmechanik (The Present Situation in Quantum Mechanics)". [Naturwissenschaften](https://en.wikipedia.org/wiki/Naturwissenschaften "Naturwissenschaften"). 23* (48): 807–812\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1935NW.....23..807S](https://ui.adsabs.harvard.edu/abs/1935NW.....23..807S). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1007/BF01491891](https://doi.org/10.1007%2FBF01491891). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [206795705](https://api.semanticscholar.org/CorpusID:206795705). "Man kann auch ganz burleske Fälle konstruieren. Eine Katze wird in eine Stahlkammer gesperrt, zusammen mit folgender Höllenmaschine (die man gegen den direkten Zugriff der Katze sichern muß): in einem Geigerschen Zählrohr befindet sich eine winzige Menge radioaktiver Substanz, so wenig, daß im Laufe einer Stunde vielleicht eines von den Atomen zerfällt, ebenso wahrscheinlich aber auch keines; geschieht es, so spricht das Zählrohr an und betätigt über ein Relais ein Hämmerchen, das ein Kölbchen mit Blausäure zertrümmert. Hat man dieses ganze System eine Stunde lang sich selbst überlassen, so wird man sich sagen, daß die Katze noch lebt, wenn inzwischen kein Atom zerfallen ist. Der erste Atomzerfall würde sie vergiftet haben. Die Psi-Funktion des ganzen Systems würde das so zum Ausdruck bringen, daß in ihr die lebende und die tote Katze (s.v.v.) \[sit venia verbo\] zu gleichen Teilen gemischt oder verschmiert sind. Das Typische an solchen Fällen ist, daß eine ursprünglich auf den Atombereich beschränkte Unbestimmtheit sich in grobsinnliche Unbestimmtheit umsetzt, die sich dann durch direkte Beobachtung entscheiden läßt. Das hindert uns, in so naiver Weise ein "verwaschenes Modell" als Abbild der Wirklichkeit gelten zu lassen. An sich enthielte es nichts Unklares oder Widerspruchsvolles. Es ist ein Unterschied zwischen einer verwackelten oder unscharf eingestellten Photographie und einer Aufnahme von Wolken und Nebelschwaden." 2. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Fine_2-0) [Fine, Arthur](https://en.wikipedia.org/wiki/Arthur_Fine "Arthur Fine"). ["The Einstein-Podolsky-Rosen Argument in Quantum Theory"](https://plato.stanford.edu/entries/qt-epr/). Stanford Encyclopedia of Philosophy. Retrieved June 11, 2020. 3. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-3) [Ball, Philip](https://en.wikipedia.org/wiki/Philip_Ball "Philip Ball") (June 25, 2018). ["Real-Life Schrödinger's Cats Probe the Boundary of the Quantum World"](https://web.archive.org/web/20250228155932/https://www.quantamagazine.org/real-life-schrodingers-cats-probe-the-boundary-of-the-quantum-world-20180625/). Quanta Magazine. Archived from [the original](https://www.quantamagazine.org/real-life-schrodingers-cats-probe-the-boundary-of-the-quantum-world-20180625/) on February 28, 2025. Retrieved February 24, 2025. 4. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-4) Einstein, A.; Podolsky, B.; Rosen, N. (May 15, 1935). "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?". Physical Review. 47 (10): 777–780\. [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/PhysRev.47.777](https://doi.org/10.1103%2FPhysRev.47.777). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0031-899X](https://search.worldcat.org/issn/0031-899X). 5. ^ [*a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-1) [c](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Stanford1_5-2) Fine, Arthur (2017). ["The Einstein-Podolsky-Rosen Argument in Quantum Theory"](https://plato.stanford.edu/entries/qt-epr/). Stanford Encyclopedia of Philosophy. Stanford University. Retrieved April 11, 2021. 6. ^ [a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-1) [c](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-2) [d](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-3) [e](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-BaggottStory_6-4) Baggott, J. E. (2013). The quantum story: a history in 40 moments* (Impression: 3 ed.). Oxford: Oxford Univ. Press. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-0-19-965597-7](https://en.wikipedia.org/wiki/Special:BookSources/978-0-19-965597-7 "Special:BookSources/978-0-19-965597-7") . 7. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Polkinghorne_7-0) Polkinghorne, J. C. (1985). [The Quantum World](https://books.google.com/books?id=lp4JPYnLrtEC&q=%22schrodinger%27s+cat%22+%22alive+dead&pg=PA67). [Princeton University Press](https://en.wikipedia.org/wiki/Princeton_University_Press "Princeton University Press"). p. 67. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [0-691-02388-3](https://en.wikipedia.org/wiki/Special:BookSources/0-691-02388-3 "Special:BookSources/0-691-02388-3") . [Archived](https://web.archive.org/web/20150519001623/https://books.google.com/books?id=lp4JPYnLrtEC&pg=PA67&dq=%22schrodinger%27s+cat%22+%22alive+dead) from the original on May 19, 2015. Retrieved November 20, 2020. 8. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Tetlow_8-0) Tetlow, Philip (2012). [Understanding Information and Computation: From Einstein to Web Science](https://books.google.com/books?id=Rk7O3EG0Xn4C&q=%22alive+and+dead%22&pg=PA321). Gower Publishing, Ltd. p. 321. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-4094-4040-6](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4094-4040-6 "Special:BookSources/978-1-4094-4040-6") . [Archived](https://web.archive.org/web/20150519001741/https://books.google.com/books?id=Rk7O3EG0Xn4C&pg=PA321&dq=%22alive+and+dead%22) from the original on May 19, 2015. 9. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-9) Lazarou, Dimitris (2007). "Interpretation of quantum theory - An overview". [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[0712\.3466](https://arxiv.org/abs/0712.3466) \[[quant-ph](https://arxiv.org/archive/quant-ph)\]. 10. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-10) Trimmer, John D. (1980). "The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper". Proceedings of the American Philosophical Society. 124 (5): 323–338\. [JSTOR](https://en.wikipedia.org/wiki/JSTOR_\(identifier\) "JSTOR (identifier)") [986572](https://www.jstor.org/stable/986572). The English translation here is based on the German original, not on the inaccurate version in this source's translation of the entire article: [Schrödinger: "The Present Situation in Quantum Mechanics." 5. Are the Variables Really Blurred?](http://web.archive.org/web/20161020061333/https://www.tuhh.de/rzt/rzt/it/QM/cat.html) 11. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-11) Maxwell, Nicholas (January 1, 1993). "Induction and Scientific Realism: Einstein versus van Fraassen Part Three: Einstein, Aim-Oriented Empiricism and the Discovery of Special and General Relativity". The British Journal for the Philosophy of Science. 44 (2): 275–305\. [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1093/bjps/44.2.275](https://doi.org/10.1093%2Fbjps%2F44.2.275). [JSTOR](https://en.wikipedia.org/wiki/JSTOR_\(identifier\) "JSTOR (identifier)") [687649](https://www.jstor.org/stable/687649). 12. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-PeresCat_12-0) [Peres, Asher](https://en.wikipedia.org/wiki/Asher_Peres "Asher Peres") (January 1988). ["Schrödinger's immortal cat"](http://link.springer.com/10.1007/BF01882873). Foundations of Physics. 18 (1): 57–76\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1988FoPh...18...57P](https://ui.adsabs.harvard.edu/abs/1988FoPh...18...57P). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1007/BF01882873](https://doi.org/10.1007%2FBF01882873). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0015-9018](https://search.worldcat.org/issn/0015-9018). 13. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-SchlosshauerDecoherenceReview_13-0) Schlosshauer, Maximilian (February 23, 2005). ["Decoherence, the measurement problem, and interpretations of quantum mechanics"](https://link.aps.org/doi/10.1103/RevModPhys.76.1267). Reviews of Modern Physics. 76 (4): 1267–1305\. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[quant-ph/0312059](https://arxiv.org/abs/quant-ph/0312059). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2004RvMP...76.1267S](https://ui.adsabs.harvard.edu/abs/2004RvMP...76.1267S). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/RevModPhys.76.1267](https://doi.org/10.1103%2FRevModPhys.76.1267). 14. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Wimmel1992_14-0) Wimmel, Hermann (1992). [Quantum physics & observed reality: a critical interpretation of quantum mechanics](https://books.google.com/books?id=-4sJ_fgyZJEC&pg=PA2). World Scientific. p. 2. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-981-02-1010-6](https://en.wikipedia.org/wiki/Special:BookSources/978-981-02-1010-6 "Special:BookSources/978-981-02-1010-6") . [Archived](https://web.archive.org/web/20130520185205/http://books.google.com/books?id=-4sJ_fgyZJEC&pg=PA2) from the original on May 20, 2013. Retrieved May 9, 2011. 15. ^ [*a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Tales_of_the_Quantum_15-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Tales_of_the_Quantum_15-1) Hobson, Art (2017). [Tales of the Quantum: Understanding Physics' Most Fundamental Theory](https://books.google.com/books?id=mGduDQAAQBAJ). New York, NY: Oxford University Press. pp. 200–202\. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-0-19-067963-7](https://en.wikipedia.org/wiki/Special:BookSources/978-0-19-067963-7 "Special:BookSources/978-0-19-067963-7") . Retrieved April 8, 2022. 16. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-16)* [Omnès, Roland](https://en.wikipedia.org/wiki/Roland_Omn%C3%A8s "Roland Omnès") (1999). [Understanding Quantum Mechanics](https://books.google.com/books?id=XET_DwAAQBAJ). Princeton, New Jersey: Princeton University Press. pp. 60–62\. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [0-691-00435-8](https://en.wikipedia.org/wiki/Special:BookSources/0-691-00435-8 "Special:BookSources/0-691-00435-8") . Retrieved April 8, 2022. 17. ^ [*a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Surfing_the_Quantum_World_17-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Surfing_the_Quantum_World_17-1) Levin, Frank S. (2017). [Surfing the Quantum World](https://books.google.com/books?id=Y1w-DwAAQBAJ). New York, NY: Oxford University Press. pp. 229–232\. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-0-19-880827-5](https://en.wikipedia.org/wiki/Special:BookSources/978-0-19-880827-5 "Special:BookSources/978-0-19-880827-5") . Retrieved April 8, 2022. 18. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-18)* Puri, Ravinder R. (2017). [Non-Relativistic Quantum Mechanics](https://books.google.com/books?id=qDbSDgAAQBAJ). Cambridge, United Kingdom: Cambridge University Press. p. 146. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-107-16436-9](https://en.wikipedia.org/wiki/Special:BookSources/978-1-107-16436-9 "Special:BookSources/978-1-107-16436-9") . Retrieved April 8, 2022. 19. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Carpenter2006_19-0) Carpenter RHS; Anderson AJ (2006). ["The death of Schrödinger's cat and of consciousness-based wave-function collapse"](https://web.archive.org/web/20061130173850/http://www.ensmp.fr/aflb/AFLB-311/aflb311m387.pdf) (PDF). [Annales de la Fondation Louis de Broglie](https://en.wikipedia.org/wiki/Annales_de_la_Fondation_Louis_de_Broglie "Annales de la Fondation Louis de Broglie"). 31 (1): 45–52\. Archived from [the original](http://www.ensmp.fr/aflb/AFLB-311/aflb311m387.pdf) (PDF) on November 30, 2006. Retrieved September 10, 2010. 20. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Okon2006_20-0) Okón E, Sebastián MA (2016). "How to Back up or Refute Quantum Theories of Consciousness". Mind and Matter. 14 (1): 25–49\. 21. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Faye2008_21-0) [Faye, J](https://en.wikipedia.org/wiki/Jan_Faye "Jan Faye") (January 24, 2008). ["Copenhagen Interpretation of Quantum Mechanics"](http://plato.stanford.edu/entries/qm-copenhagen/). [Stanford Encyclopedia of Philosophy](https://en.wikipedia.org/wiki/Stanford_Encyclopedia_of_Philosophy "Stanford Encyclopedia of Philosophy"). The Metaphysics Research Lab Center for the Study of Language and Information, [Stanford University](https://en.wikipedia.org/wiki/Stanford_University "Stanford University"). Retrieved September 19, 2010. 22. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-22) [John Bell](https://en.wikipedia.org/wiki/John_Stewart_Bell "John Stewart Bell") (1990). "Against 'measurement'". Physics World. 3 (8): 33–41\. [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1088/2058-7058/3/8/26](https://doi.org/10.1088%2F2058-7058%2F3%2F8%2F26). 23. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-23) [Niels Bohr](https://en.wikipedia.org/wiki/Niels_Bohr "Niels Bohr") (1985) \[May 16, 1947\]. Jørgen Kalckar (ed.). [Foundations of Quantum Physics I (1926-1932)](https://www.nbarchive.dk/publications/bcw/). Niels Bohr: Collected Works. Vol. 6. pp. 451–454\. 24. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-24) Stig Stenholm (1983). "To fathom space and time". In [Pierre Meystre](https://en.wikipedia.org/w/index.php?title=Pierre_Meystre&action=edit&redlink=1 "Pierre Meystre (page does not exist)") (ed.). Quantum Optics, Experimental Gravitation, and Measurement Theory. Plenum Press. p. 121. "The role of irreversibility in the theory of measurement has been emphasized by many. Only this way can a permanent record be obtained. The fact that separate pointer positions must be of the asymptotic nature usually associated with irreversibility has been utilized in the measurement theory of Daneri, Loinger and Prosperi (1962). It has been accepted as a formal representation of Bohr's ideas by Rosenfeld (1966)." 25. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-25) Haake, Fritz (April 1, 1993). "Classical motion of meter variables in the quantum theory of measurement". [Physical Review A](https://en.wikipedia.org/wiki/Physical_Review_A "Physical Review A"). 47 (4): 2506–2517\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1993PhRvA..47.2506H](https://ui.adsabs.harvard.edu/abs/1993PhRvA..47.2506H). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/PhysRevA.47.2506](https://doi.org/10.1103%2FPhysRevA.47.2506). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [9909217](https://pubmed.ncbi.nlm.nih.gov/9909217). 26. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-zurek03_26-0) [Zurek, Wojciech H.](https://en.wikipedia.org/wiki/Wojciech_H._Zurek "Wojciech H. Zurek") (2003). "Decoherence, einselection, and the quantum origins of the classical". Reviews of Modern Physics. 75 (3): 715. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[quant-ph/0105127](https://arxiv.org/abs/quant-ph/0105127). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2003RvMP...75..715Z](https://ui.adsabs.harvard.edu/abs/2003RvMP...75..715Z). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/revmodphys.75.715](https://doi.org/10.1103%2Frevmodphys.75.715). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [14759237](https://api.semanticscholar.org/CorpusID:14759237). 27. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-zurek91_27-0) [Wojciech H. Zurek](https://en.wikipedia.org/wiki/Wojciech_H._Zurek "Wojciech H. Zurek"), "Decoherence and the transition from quantum to classical", Physics Today, 44, pp. 36–44 (1991) 28. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-28) Home, D.; Whitaker, M. A. B. (1992). "Ensemble Interpretations of Quantum Mechanics: A Modern Perspective". Physics Reports. 210 (4): 223–317\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1992PhR...210..223H](https://ui.adsabs.harvard.edu/abs/1992PhR...210..223H). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1016/0370-1573(92)90088-H](https://doi.org/10.1016%2F0370-1573%2892%2990088-H). 29. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-29) [Rovelli, Carlo](https://en.wikipedia.org/wiki/Carlo_Rovelli "Carlo Rovelli") (1996). "Relational Quantum Mechanics". International Journal of Theoretical Physics. 35 (8): 1637–1678\. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[quant-ph/9609002](https://arxiv.org/abs/quant-ph/9609002). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1996IJTP...35.1637R](https://ui.adsabs.harvard.edu/abs/1996IJTP...35.1637R). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1007/BF02302261](https://doi.org/10.1007%2FBF02302261). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [16325959](https://api.semanticscholar.org/CorpusID:16325959). 30. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-30) Cramer, John G. (July 1986). ["The transactional interpretation of quantum mechanics"](https://www.researchgate.net/publication/280926546). Reviews of Modern Physics. 58 (3): 647–685\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1986RvMP...58..647C](https://ui.adsabs.harvard.edu/abs/1986RvMP...58..647C). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/RevModPhys.58.647](https://doi.org/10.1103%2FRevModPhys.58.647). 31. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-31) Okon, Elias; Sudarsky, Daniel (February 1, 2014). "Benefits of Objective Collapse Models for Cosmology and Quantum Gravity". Foundations of Physics. 44 (2): 114–143\. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[1309\.1730](https://arxiv.org/abs/1309.1730). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2014FoPh...44..114O](https://ui.adsabs.harvard.edu/abs/2014FoPh...44..114O). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1007/s10701-014-9772-6](https://doi.org/10.1007%2Fs10701-014-9772-6). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [1572-9516](https://search.worldcat.org/issn/1572-9516). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [67831520](https://api.semanticscholar.org/CorpusID:67831520). 32. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-32) Khazali, Mohammadsadegh; Lau, Hon Wai; Humeniuk, Adam; Simon, Christoph (August 11, 2016). "Large energy superpositions via Rydberg dressing". Physical Review A. 94 (2) 023408. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[1509\.01303](https://arxiv.org/abs/1509.01303). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2016PhRvA..94b3408K](https://ui.adsabs.harvard.edu/abs/2016PhRvA..94b3408K). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/physreva.94.023408](https://doi.org/10.1103%2Fphysreva.94.023408). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [2469-9926](https://search.worldcat.org/issn/2469-9926). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [118364289](https://api.semanticscholar.org/CorpusID:118364289). 33. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-33) ["What is the world's biggest Schrodinger cat?"](http://physics.stackexchange.com/questions/3309/what-is-the-worlds-biggest-schrodinger-cat). stackexchange.com. [Archived](https://web.archive.org/web/20120108000629/http://physics.stackexchange.com/questions/3309/what-is-the-worlds-biggest-schrodinger-cat) from the original on January 8, 2012. 34. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-34) ["NIST Researchers Create 'Quantum Cats' Made of Light"](https://web.archive.org/web/20170507224218/https://www.nist.gov/news-events/news/2010/08/nist-researchers-create-quantum-cats-made-light). NIST. August 31, 2010. Archived from [the original](https://www.nist.gov/news-events/news/2010/08/nist-researchers-create-quantum-cats-made-light) on May 7, 2017. 35. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-35) Sychev, Demid V.; Ulanov, Alexander E.; Pushkina, Anastasia A.; Richards, Matthew W.; Fedorov, Ilya A.; Lvovsky, Alexander I. (June 2017). ["Enlargement of optical Schrödinger's cat states"](https://www.nature.com/articles/nphoton.2017.57). Nature Photonics. 11 (6): 379–382\. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[1609\.08425](https://arxiv.org/abs/1609.08425). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2017NaPho..11..379S](https://ui.adsabs.harvard.edu/abs/2017NaPho..11..379S). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1038/nphoton.2017.57](https://doi.org/10.1038%2Fnphoton.2017.57). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [1749-4885](https://search.worldcat.org/issn/1749-4885). 36. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-36) Monroe, C.; Meekhof, D. M.; King, B. E.; Wineland, D. J. (May 24, 1996). "A "Schrödinger's cat" Superposition State of an Atom". Science. 272 (5265): 1131–1136\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1996Sci...272.1131M](https://ui.adsabs.harvard.edu/abs/1996Sci...272.1131M). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1126/science.272.5265.1131](https://doi.org/10.1126%2Fscience.272.5265.1131). [PMID](https://en.wikipedia.org/wiki/PMID_\(identifier\) "PMID (identifier)") [8662445](https://pubmed.ncbi.nlm.nih.gov/8662445). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [2311821](https://api.semanticscholar.org/CorpusID:2311821). 37. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-37) ["Physics World: Schrödinger's cat comes into view"](https://physicsworld.com/a/schrodingers-cat-comes-into-view/). July 5, 2000. 38. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-38) Castelvecchi, Davide. ["Macro-Weirdness: "Quantum Microphone" Puts Naked-Eye Object in 2 Places at Once"](https://web.archive.org/web/20120319021316/http://www.scientificamerican.com/article.cfm?id=quantum-microphone). Scientific American. Archived from [the original](https://www.scientificamerican.com/article/quantum-microphone/) on March 19, 2012. 39. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-39) Romero-Isart, O.; Juan, M. L.; Quidant, R.; Cirac, J. I. (2010). "Toward Quantum Superposition of Living Organisms". New Journal of Physics. 12 (3) 033015. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[0909\.1469](https://arxiv.org/abs/0909.1469). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2010NJPh...12c3015R](https://ui.adsabs.harvard.edu/abs/2010NJPh...12c3015R). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1088/1367-2630/12/3/033015](https://doi.org/10.1088%2F1367-2630%2F12%2F3%2F033015). [S2CID](https://en.wikipedia.org/wiki/S2CID_\(identifier\) "S2CID (identifier)") [59151724](https://api.semanticscholar.org/CorpusID:59151724). 40. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-40) ["Could 'Schrödinger's bacterium' be placed in a quantum superposition?"](http://physicsworld.com/cws/article/news/2015/sep/21/could-schrodingers-bacterium-be-placed-in-a-quantum-superposition). physicsworld.com. [Archived](https://web.archive.org/web/20160730174613/http://physicsworld.com/cws/article/news/2015/sep/21/could-schrodingers-bacterium-be-placed-in-a-quantum-superposition) from the original on July 30, 2016. 41. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-LS-20191107_41-0) Najjar, Dana (November 7, 2019). ["Physicists Can Finally Peek at Schrödinger's Cat Without Killing It Forever"](https://www.livescience.com/schrodingers-cat-can-be-peeked-at.html). [Live Science](https://en.wikipedia.org/wiki/Live_Science "Live Science"). Retrieved November 7, 2019. 42. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-NJP-20191001_42-0) Patekar, Kartik; Hofmann, Holger F. (2019). ["The role of system–meter entanglement in controlling the resolution and decoherence of quantum measurements"](https://doi.org/10.1088%2F1367-2630%2Fab4451). [New Journal of Physics](https://en.wikipedia.org/wiki/New_Journal_of_Physics "New Journal of Physics"). 21 (10): 103006. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[1905\.09978](https://arxiv.org/abs/1905.09978). [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2019NJPh...21j3006P](https://ui.adsabs.harvard.edu/abs/2019NJPh...21j3006P). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1088/1367-2630/ab4451](https://doi.org/10.1088%2F1367-2630%2Fab4451). 43. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-43) Crease, Robert P. (May 27, 2024). ["Ursula Le Guin: the pioneering author we should thank for popularizing Schrödinger's cat"](https://physicsworld.com/a/ursula-le-guin-the-pioneering-author-we-should-thank-for-popularizing-schrodingers-cat/). Physics World. Retrieved October 27, 2024. 44. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-100CCC_44-0) Sam Stall (May 1, 2007). [100 Cats Who Changed Civilization](https://books.google.com/books?id=coXIF8WbEKEC). Quirk Books. p. 34. [ISBN](https://en.wikipedia.org/wiki/ISBN_\(identifier\) "ISBN (identifier)") [978-1-59474-163-0](https://en.wikipedia.org/wiki/Special:BookSources/978-1-59474-163-0 "Special:BookSources/978-1-59474-163-0") . 45. ^ [*a](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Crease_45-0) [b](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Crease_45-1) Crease, Robert P. (2012). ["The cat that never dies"](https://doi.org/10.1088%2F2058-7058%2F25%2F04%2F27). Physics World. 25* (4): 18–19\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2012PhyW...25d..18C](https://ui.adsabs.harvard.edu/abs/2012PhyW...25d..18C). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1088/2058-7058/25/04/27](https://doi.org/10.1088%2F2058-7058%2F25%2F04%2F27). 46. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-46) Ryan, Marie-Laure (2011). ["Narrative/Science Entanglements: On the Thousand and One Literary Lives of Schrödinger's Cat"](https://www.jstor.org/stable/41289295). Narrative. 19 (2): 171–186\. [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [1063-3685](https://search.worldcat.org/issn/1063-3685). [JSTOR](https://en.wikipedia.org/wiki/JSTOR_\(identifier\) "JSTOR (identifier)") [41289295](https://www.jstor.org/stable/41289295). 47. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-47) Kravitz, Bennett (2013). ["Thoughts on the Anti-Detective in Paul Auster's "New York Trilogy", Adam Ross's "Mister Peanut", and Martha Grimes' "The Old Wine Shades""](https://www.jstor.org/stable/23610151). Studies in Popular Culture. 36 (1): 45–61\. [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0888-5753](https://search.worldcat.org/issn/0888-5753). [JSTOR](https://en.wikipedia.org/wiki/JSTOR_\(identifier\) "JSTOR (identifier)") [23610151](https://www.jstor.org/stable/23610151). 48. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-48) Branzburg, Judith V. (October 31, 2000). ["Dead cats and live bodies"](https://www.proquest.com/openview/a751e740ad411cd002452117c93b4322). The Lesbian Review of Books. 7 (1): 3. 49. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-49) ["SFE: Wilson, Robert Anton"](https://sf-encyclopedia.com/entry/wilson_robert_anton). sf-encyclopedia.com. Retrieved December 3, 2022. 50. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-50) ["SFE: Thought Experiment"](https://sf-encyclopedia.com/entry/thought_experiment). sf-encyclopedia.com. Retrieved December 3, 2022. 51. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-51) Goldberg, Matt (April 17, 2020). ["A Serious Man Ending Explained: The Crucible of American Judaism"](https://collider.com/a-serious-man-ending-explained-american-judaism/). Collider. Retrieved December 3, 2022. 52. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-52) Orr, Christopher (September 25, 2014). ["30 Years of Coens: A Serious Man"](https://web.archive.org/web/20221203220152/https://www.theatlantic.com/entertainment/archive/2014/09/30-years-of-coens-a-serious-man/380732/). [The Atlantic](https://en.wikipedia.org/wiki/The_Atlantic "The Atlantic"). Archived from [the original](https://www.theatlantic.com/entertainment/archive/2014/09/30-years-of-coens-a-serious-man/380732/) on December 3, 2022. Retrieved December 3, 2022. 53. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-53) [Ebert, Roger](https://en.wikipedia.org/wiki/Roger_Ebert "Roger Ebert") (March 4, 2013). ["The Coen Brothers and Serious Quantum Theory"](https://web.archive.org/web/20201029024134/https://www.rogerebert.com/roger-ebert/the-coen-brothers-and-serious-quantum-theory). [Chicago Sun Times](https://en.wikipedia.org/wiki/Chicago_Sun_Times "Chicago Sun Times"). Archived from [the original](https://www.rogerebert.com/roger-ebert/the-coen-brothers-and-serious-quantum-theory) on October 29, 2020. 54. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-54) Collis, Clark (June 20, 2014). ["Coherence"](https://web.archive.org/web/20221203220151/https://ew.com/article/2014/06/20/coherence/). Entertainment Weekly. Archived from [the original](https://ew.com/article/2014/06/20/coherence/) on December 3, 2022. Retrieved December 3, 2022. 55. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-55) Landsman, Peggy (April 1, 2022). [""Schrodinger's Cat""](https://web.archive.org/web/20220529020959/https://www.scientificamerican.com/article/poem-schroedingers-cat/). Scientific American. Archived from [the original](https://www.scientificamerican.com/article/poem-schroedingers-cat/) on May 29, 2022. Retrieved February 22, 2023. 56. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-56) Robbins, Hollis. [""His Paws Upon The Dish""](http://www.percontra.net/issues/34/poetry/his-paws-upon-the/). Per Contra Journal. Per Contra. Retrieved February 22, 2023. 57. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodinger's_Girlfriend_57-0) Ehren, Christine (November 18, 2001). ["World Premiere Schrodinger's Girlfriend Closes Nov. 18 at San Fran's Magic"](https://web.archive.org/web/20100517085507/http://www.playbill.com/news/article/63363-World-Premiere-Schrodingers-Girlfriend-Closes-Nov-18-at-San-Frans-Magic). Schrodingers Girlfriend. Playbill Review. Archived from [the original](http://www.playbill.com/news/article/63363-World-Premiere-Schrodingers-Girlfriend-Closes-Nov-18-at-San-Frans-Magic) on May 17, 2010. Retrieved January 6, 2015. 58. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-Schrodingers_Girlfriend_SFG_58-0) Hurwitt, Robert (November 5, 2001). ["'Girlfriend' runs out of inspiration / Ideas bog down physics comedy"](https://web.archive.org/web/20151126043542/http://www.sfgate.com/entertainment/article/Girlfriend-runs-out-of-inspiration-Ideas-bog-2862061.php). SFGate Review. Archived from [the original](http://www.sfgate.com/entertainment/article/Girlfriend-runs-out-of-inspiration-Ideas-bog-2862061.php) on November 26, 2015. Retrieved December 5, 2015. 59. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-59) Mohan, Geoffrey (August 12, 2013). ["Google doodle honors physicist Erwin Schrodinger and his cat"](https://web.archive.org/web/20221202232119/https://www.baltimoresun.com/la-sci-sn-schrodinger-cat-20130812-story.html). Baltimore Sun. Archived from [the original](https://www.baltimoresun.com/la-sci-sn-schrodinger-cat-20130812-story.html) on December 2, 2022. Retrieved December 2, 2022. 60. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-The_Age_60-0) Farrer, Gordon (January 6, 2006). ["Sum thing to do with maths genius"](https://web.archive.org/web/20080115093824/http://www.theage.com.au/news/tv--radio/sum-thing-to-do-with-maths-genius/2006/01/05/1136387564868.html). The Age. Melbourne. Archived from [the original](http://www.theage.com.au/news/tv--radio/sum-thing-to-do-with-maths-genius/2006/01/05/1136387564868.html) on January 15, 2008. Retrieved August 28, 2007. 61. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-61) [Singh, Simon](https://en.wikipedia.org/wiki/Simon_Singh "Simon Singh") (October 2014). ["Theories of quantum levity"](https://iopscience.iop.org/article/10.1088/2058-7058/27/10/41). Physics World. 27 (10): 80. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[2014PhyW...27j..80S](https://ui.adsabs.harvard.edu/abs/2014PhyW...27j..80S). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1088/2058-7058/27/10/41](https://doi.org/10.1088%2F2058-7058%2F27%2F10%2F41). [ISSN](https://en.wikipedia.org/wiki/ISSN_\(identifier\) "ISSN (identifier)") [0953-8585](https://search.worldcat.org/issn/0953-8585). 62. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-62) ["The Famous Schrodinger's Cat Thought Experiment Gets Brought to Life in an Off-Kilter Animation"](https://web.archive.org/web/20221202230558/https://www.openculture.com/2017/03/the-famous-schrodingers-cat-thought-experiment-gets-brought-to-life-in-an-off-kilter-animation.html). Open Culture. March 24, 2017. Archived from [the original](https://www.openculture.com/2017/03/the-famous-schrodingers-cat-thought-experiment-gets-brought-to-life-in-an-off-kilter-animation.html) on December 2, 2022. Retrieved December 2, 2022. 63. [^](https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#cite_ref-63) ["NIGHTMARE シュレーディンガーナイフ歌詞 – 歌詞探索【歌詞リリ】"](https://web.archive.org/web/20230528210243/https://www.lyrical-nonsense.com/lyrics/nightmare/shrodinger-knife/). Lyrical Nonsense. Archived from [the original](https://www.lyrical-nonsense.com/lyrics/nightmare/shrodinger-knife/) on May 28, 2023. Retrieved May 28, 2023. Further reading - [Einstein, Albert](https://en.wikipedia.org/wiki/Albert_Einstein "Albert Einstein"); [Podolsky, Boris](https://en.wikipedia.org/wiki/Boris_Podolsky "Boris Podolsky"); [Rosen, Nathan](https://en.wikipedia.org/wiki/Nathan_Rosen "Nathan Rosen") (May 15, 1935). ["Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?"](https://doi.org/10.1103%2FPhysRev.47.777). Physical Review. 47 (10): 777–780\. [Bibcode](https://en.wikipedia.org/wiki/Bibcode_\(identifier\) "Bibcode (identifier)"):[1935PhRv...47..777E](https://ui.adsabs.harvard.edu/abs/1935PhRv...47..777E). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1103/PhysRev.47.777](https://doi.org/10.1103%2FPhysRev.47.777). - Leggett, Tony (August 2000). ["New Life for Schrödinger's Cat"](https://jrfriedman.people.amherst.edu/Leggett%20Physics%20World%20article/PW%20article.pdf) (PDF). Physics World. pp. 23–24. Retrieved February 28, 2020. An article on experiments with "cat state" superpositions in superconducting rings, in which the electrons go around the ring in two directions simultaneously. - Trimmer, John D. (1980). "The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper". [Proceedings of the American Philosophical Society](https://en.wikipedia.org/wiki/Proceedings_of_the_American_Philosophical_Society "Proceedings of the American Philosophical Society"). 124 (5): 323–338\. [JSTOR](https://en.wikipedia.org/wiki/JSTOR_\(identifier\) "JSTOR (identifier)") [986572](https://www.jstor.org/stable/986572). ([registration required](https://en.wikipedia.org/wiki/Wikipedia:Verifiability#Access_to_sources "Wikipedia:Verifiability")) - Yam, Phillip (October 9, 2012). ["Bringing Schrödinger's Cat to Life"](https://www.scientificamerican.com/article/bringing-schrodingers-quantum-cat-to-life/). Scientific American. Retrieved February 28, 2020. A description of investigations of quantum "cat states" and wave function collapse by [Serge Haroche](https://en.wikipedia.org/wiki/Serge_Haroche "Serge Haroche") and [David J. Wineland](https://en.wikipedia.org/wiki/David_J._Wineland "David J. Wineland"), for which they won the 2012 [Nobel Prize in Physics](https://en.wikipedia.org/wiki/List_of_Nobel_laureates_in_Physics "List of Nobel laureates in Physics"). - Violaris, M. (2023). A Physics Lab Inside Your Head: Quantum Thought Experiments as an Educational Tool. 2023 IEEE International Conference on Quantum Computing and Engineering (QCE). Bellevue, WA, USA. pp. 58–67\. [arXiv](https://en.wikipedia.org/wiki/ArXiv_\(identifier\) "ArXiv (identifier)"):[2312\.07840](https://arxiv.org/abs/2312.07840). [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.1109/QCE57702.2023.20325](https://doi.org/10.1109%2FQCE57702.2023.20325). Reduction of the Schrödinger's cat to a simple [quantum circuit](https://en.wikipedia.org/wiki/Quantum_circuit "Quantum circuit"). External links - [A spoken word version](https://en.wikipedia.org/wiki/File:Schrodingers-cat.ogg "File:Schrodingers-cat.ogg") of this article (created from a revision of the article dated 2013-08-12). - [Schrödinger's Cat](http://www.informationphilosopher.com/solutions/experiments/schrodingerscat/) from the Information Philosopher. - [Schrödinger's Cat - Sixty Symbols](http://www.sixtysymbols.com/videos/schrodinger.htm) - a video published by the [University of Nottingham](https://en.wikipedia.org/wiki/University_of_Nottingham "University of Nottingham"). - [Schrödinger's Cat](https://soundcloud.com/siftpodcast/schr-dingers-cat) - a podcast produced by Sift.
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