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Schrödinger's cat: a cat, a flask of poison, and a [[radioactive source are placed in a sealed box. If an internal monitor (e.g. Geiger counter) detects radioactivity (i.e. a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. The Copenhagen interpretation of quantum mechanics implies that after a while, the cat is simultaneously alive and dead. 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 collapses into one possibility or the other.]]

Schrödinger's cat: a cat, a flask of poison, and a [[radioactive source are placed in a sealed box. If an internal monitor (e.g. Geiger counter) detects radioactivity (i.e. a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. The Copenhagen interpretation of quantum mechanics implies that after a while, the cat is simultaneously alive and dead. 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 collapses into one possibility or the other.]]

薛定谔的猫：将一只猫，一瓶毒药和放射源放置在密闭容器里。如果盒内监测器（例如盖革计数器）检测到放射性（即单个原子衰变），则烧瓶会破碎，释放出毒药，从而杀死猫。量子力学的'''<font color="ff8000">哥本哈根诠释Copenhagen interpretation</font>'''表明，一段时间之后，这只猫既是死的又是活的。然而，当人们往盒子里看时，猫不是活着的就是死了，而不是既活着又死了。这就提出了一个问题，即量子叠加具体何时结束而现实何时塌陷成一种或另一种可能性。

薛定谔的猫：将一只猫，一瓶毒药和放射源入密闭容器。如果盒内监测器（如盖革计数器）检测到放射性，即单个原子衰变，烧瓶会破碎，毒药释放，杀死猫。量子力学的'''<font color="ff8000">哥本哈根诠释Copenhagen interpretation</font>'''表为，一段时间之后，猫既活着又死了。但是，人们看向盒内时，猫不是活着就是死了，不可能既活着又死了。这就提出了一个问题，量子叠加具体何时结束，现实何时塌陷成一种或另一种可能性。

'''Schrödinger's cat''' is a [[thought experiment]], sometimes described as a [[paradox]], devised by Austrian physicist [[Erwin Schrödinger]] in 1935, though the idea originated from [[Albert Einstein]].<ref name="Schrodinger1935"><br>

'''Schrödinger's cat''' is a [[thought experiment]], sometimes described as a [[paradox]], devised by Austrian physicist [[Erwin Schrödinger]] in 1935, though the idea originated from [[Albert Einstein]].<ref name="Schrodinger1935"><br>

</ref>薛定谔的猫是一个'''<font color="ff8000">思维实验thought experiment</font>'''，有时被称为'''<font color="ff8000">悖论paradox</font>'''，由奥地利物理学家埃尔温·薛定谔于1935年提出，但该想法起源于阿尔伯特·爱因斯坦。

</ref>薛定谔的猫是一个'''<font color="ff8000">思想实验thought experiment</font>'''，有时被称为'''<font color="ff8000">悖论paradox</font>'''，由奥地利物理学家埃尔温·薛定谔于1935年提出，但该想法起源于阿尔伯特·爱因斯坦。

</ref> It illustrates what he saw as the problem of the [[Copenhagen interpretation]] of [[quantum mechanics]] applied to everyday objects. The scenario presents a hypothetical [[cat]] that may be simultaneously both alive and dead,<ref name="Moring">{{cite book<br>

</ref> It illustrates what he saw as the problem of the [[Copenhagen interpretation]] of [[quantum mechanics]] applied to everyday objects. The scenario presents a hypothetical [[cat]] that may be simultaneously both alive and dead,<ref name="Moring">{{cite book<br>

</ref>该实验说明了他所认为的将'''<font color="ff8000">量子力学quantum mechanics</font>'''的哥本哈根诠释应用于日常物品所产生的问题。这个场景中有一只假想的猫，它可能同时活着和死去。ref name"moring"{ cite book<br>

</ref>该实验表明了薛定谔认为的将'''<font color="ff8000">量子力学quantum mechanics</font>'''的哥本哈根诠释应用于日常物品所产生的问题，提出了一只可能同时活着且死去的猫。ref name"moring"{ cite book<br>

   ——Solitude（讨论）该句意译

   ——Solitude（讨论）该句意译

}}</ref> a state known as a [[quantum superposition]], as a result of being linked to a random [[Subatomic particle|subatomic]] event that may or may not occur.

}}</ref> a state known as a [[quantum superposition]], as a result of being linked to a random [[Subatomic particle|subatomic]] event that may or may not occur.

}}<nowiki></ref></nowiki> a state known as a '''<font color="#ff8000">量子叠加quantum superposition</font>''', as a result of being linked to a random subatomic event that may or may not occur.<br>

<nowiki>}}</nowiki><nowiki></ref></nowiki> a state known as a '''<font color="#ff8000">quantum superposition</font>''', as a result of being linked to a random subatomic event that may or may not occur.<br>

这种状态被称为量子叠加quantum superposition，是与可能或不可能发生的随机亚原子事件相联系的结果。

这种状态被称为量子叠加quantum superposition，是与可能发生也可能不发生的随机亚原子事件相联系导致的结果。

The thought experiment is also often featured in theoretical discussions of the interpretations of quantum mechanics, particularly in situations involving the measurement problem. Schrödinger coined the term Verschränkung (entanglement) in the course of developing the thought experiment.

The thought experiment is also often featured in theoretical discussions of the interpretations of quantum mechanics, particularly in situations involving the measurement problem. Schrödinger coined the term Verschränkung (entanglement) in the course of developing the thought experiment.

==Origin and motivation==<br>

==Origin and motivation==<br>

[[File:Schroedinger cat.jpg|thumb|left|A life-size—and moveable—cat figure in the garden of Huttenstrasse 9, Zurich, where Erwin Schrödinger lived 1921–1926. A visitor to the house cannot know in advance where the cat will be.<ref>{{cite web |last1=Suarez |first1=Antoine |title=The limits of quantum superposition: Should "Schrödinger's cat" and "Wigner's friend" be considered "miracle" narratives? |url=https://www.researchgate.net/publication/334031988 |website=ResearchGate |accessdate=27 February 2020 |page=3 |date=2019}}</ref>|链接=Special:FilePath/Schroedinger_cat.jpg]]

[[File:Schroedinger cat.jpg|thumb|left|A life-size—and moveable—cat figure in the garden of Huttenstrasse 9, Zurich, where Erwin Schrödinger lived 1921–1926. A visitor to the house cannot know in advance where the cat will be.<ref>{{cite web |last1=Suarez |first1=Antoine |title=The limits of quantum superposition: Should "Schrödinger's cat" and "Wigner's friend" be considered "miracle" narratives? |url=https://www.researchgate.net/publication/334031988 |website=ResearchGate |accessdate=27 February 2020 |page=3 |date=2019}}</ref>|链接=Special:FilePath/Schroedinger_cat.jpg]]

A life-size—and moveable—cat figure in the garden of Huttenstrasse 9, Zurich, where Erwin Schrödinger lived 1921–1926. A visitor to the house cannot know in advance where the cat will be.

A life-size—and moveable—cat figure in the garden of Huttenstrasse 9, Zurich, where Erwin Schrödinger lived 1921–1926. A visitor to the house cannot know in advance where the cat will be.

Schrödinger intended his thought experiment as a discussion of the [[EPR paradox|EPR article]]—named after its authors [[Albert Einstein|Einstein]], [[Boris Podolsky|Podolsky]], and [[Nathan Rosen|Rosen]]—in 1935.<ref>[http://prola.aps.org/abstract/PR/v47/i10/p777_1 Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?] {{webarchive|url=https://web.archive.org/web/20060208145129/http://prola.aps.org/abstract/PR/v47/i10/p777_1 |date=2006-02-08 }} A. Einstein, B. Podolsky, and N. Rosen, Phys. Rev. 47, 777 (1935)</ref> The EPR article highlighted the counterintuitive nature of [[quantum superposition]]s, in which a quantum system such as an [[atom]] or [[photon]] can exist as a combination of multiple states corresponding to different possible outcomes.

Schrödinger intended his thought experiment as a discussion of the [[EPR paradox|EPR article]]—named after its authors [[Albert Einstein|Einstein]], [[Boris Podolsky|Podolsky]], and [[Nathan Rosen|Rosen]]—in 1935.<ref>[http://prola.aps.org/abstract/PR/v47/i10/p777_1 Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?] {{webarchive|url=https://web.archive.org/web/20060208145129/http://prola.aps.org/abstract/PR/v47/i10/p777_1 |date=2006-02-08 }} A. Einstein, B. Podolsky, and N. Rosen, Phys. Rev. 47, 777 (1935)</ref> The EPR article highlighted the counterintuitive nature of [[quantum superposition]]s, in which a quantum system such as an [[atom]] or [[photon]] can exist as a combination of multiple states corresponding to different possible outcomes.

Schrödinger intended his thought experiment as a discussion of the EPR article—named after its authors Einstein, Podolsky, and Rosen—in 1935. The EPR article highlighted the counterintuitive nature of quantum superpositions, in which a quantum system such as an atom or photon can exist as a combination of multiple states corresponding to different possible outcomes.

Schrödinger intended his thought experiment as a discussion of the EPR article—named after its authors Einstein, Podolsky, and Rosen—in 1935. The EPR article highlighted the counterintuitive nature of quantum superpositions, in which a quantum system such as an atom or photon can exist as a combination of multiple states corresponding to different possible outcomes.

1935年，薛定谔提出该思维实验是对'''<font color="#ff8000">EPR佯谬</font>'''论文（以其作者爱因斯坦、波多尔斯基和罗森英文首字母命名）的讨论。EPR文章强调了量子叠加的反直觉性质，在量子叠加中，一个量子系统，比如原子或者光子，可以作为对应不同可能结果的多个状态的组合而存在。

1935年，薛定谔本来想将该思想实验作为对'''<font color="#ff8000">EPR佯谬</font>'''论文（以其作者爱因斯坦、波多尔斯基和罗森英文首字母命名）的讨论。EPR论文强调了量子叠加的反直觉性，在量子叠加中，一个量子系统，比如原子或者光子，可以处于多个状态，对应不同的结果。

The prevailing theory, called the Copenhagen interpretation, says that a quantum system remains in superposition until it interacts with, or is observed by the external world. When this happens, the superposition collapses into one or another of the possible definite states. The EPR experiment shows that a system with multiple particles separated by large distances can be in such a superposition. 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.

The prevailing theory, called the Copenhagen interpretation, says that a quantum system remains in superposition until it interacts with, or is observed by the external world. When this happens, the superposition collapses into one or another of the possible definite states. The EPR experiment shows that a system with multiple particles separated by large distances can be in such a superposition. 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.

 

 

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 locked steel chamber, wherein the cat's life or death depended on the state of a [[Radioactive decay|radioactive]] atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the Copenhagen interpretation implies 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-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics.<ref name="Schrodinger1935"/>

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 locked steel chamber, wherein the cat's life or death depended on the state of a [[Radioactive decay|radioactive]] atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the Copenhagen interpretation implies 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-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics.<ref name="Schrodinger1935"/>

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 locked 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 Copenhagen interpretation implies 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-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics.

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 locked 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 Copenhagen interpretation implies 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-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics.

  ——Solitude（讨论）该句意译  

  ——Solitude（讨论）该句意译  

However, since Schrödinger's time, other 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.    Intended as a critique of the Copenhagen interpretation (the prevailing orthodoxy in 1935), the Schrödinger's cat thought experiment remains a defining touchstone for modern interpretations of quantum mechanics. Physicists often use the way each interpretation deals with Schrödinger's cat as a way of illustrating and comparing the particular features, strengths, and weaknesses of each interpretation.

However, since Schrödinger's time, other 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.    Intended as a critique of the Copenhagen interpretation (the prevailing orthodoxy in 1935), the Schrödinger's cat thought experiment remains a defining touchstone for modern interpretations of quantum mechanics. Physicists often use the way each interpretation deals with Schrödinger's cat as a way of illustrating and comparing the particular features, strengths, and weaknesses of each interpretation.

 

==Thought experiment==<br>

==Thought experiment==<br>

Schrödinger wrote:<ref name="Schrodinger1935" /><ref>{{cite journal|last1=Trimmer|first1=John D.|title=The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper|journal=Proceedings of the American Philosophical Society|date=1980|volume=124|issue=5|pages=323–338|jstor=986572}} Reproduced with some inaccuracies here:

Schrödinger wrote:<ref name="Schrodinger1935" /><ref>{{cite journal|last1=Trimmer|first1=John D.|title=The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper|journal=Proceedings of the American Philosophical Society|date=1980|volume=124|issue=5|pages=323–338|jstor=986572}} Reproduced with some inaccuracies here:

Schrödinger's famous thought 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?) If the cat survives, it remembers only being alive. But explanations of the EPR experiments that are consistent with standard microscopic quantum mechanics require that macroscopic objects, such as cats and notebooks, do not always have unique classical descriptions. The thought experiment illustrates this apparent paradox. Our intuition says that no observer can be in a mixture of states—yet the cat, it seems from the thought experiment, can be such a mixture. Is the cat required to be an observer, or does its existence in a single well-defined classical state require another external observer? Each alternative seemed absurd to Einstein, who was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote:

Schrödinger's famous thought 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?) If the cat survives, it remembers only being alive. But explanations of the EPR experiments that are consistent with standard microscopic quantum mechanics require that macroscopic objects, such as cats and notebooks, do not always have unique classical descriptions. The thought experiment illustrates this apparent paradox. Our intuition says that no observer can be in a mixture of states—yet the cat, it seems from the thought experiment, can be such a mixture. Is the cat required to be an observer, or does its existence in a single well-defined classical state require another external observer? Each alternative seemed absurd to Einstein, who was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote:

{{Quote|You are the only contemporary physicist, besides [[Max von Laue|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.<ref>{{cite journal|title=Induction and Scientific Realism: Einstein versus van Fraassen Part Three: Einstein, Aim-Oriented Empiricism and the Discovery of Special and General Relativity|first=Nicholas|last=Maxwell|date=1 January 1993|volume=44|issue=2|pages=275–305|doi=10.1093/bjps/44.2.275|jstor=687649|journal=The British Journal for the Philosophy of Science}}</ref>}}<br>

{{Quote|You are the only contemporary physicist, besides [[Max von Laue|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.<ref>{{cite journal|title=Induction and Scientific Realism: Einstein versus van Fraassen Part Three: Einstein, Aim-Oriented Empiricism and the Discovery of Special and General Relativity|first=Nicholas|last=Maxwell|date=1 January 1993|volume=44|issue=2|pages=275–305|doi=10.1093/bjps/44.2.275|jstor=687649|journal=The British Journal for the Philosophy of Science}}</ref>}}<br>

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.

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.

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.

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.

A commonly held interpretation of quantum mechanics is the Copenhagen interpretation.  In the Copenhagen interpretation, a system stops being a superposition of states and becomes either one or the other when an observation takes place. This thought experiment makes apparent the fact that the nature of measurement, or observation, is not well-defined in this interpretation. The experiment can be interpreted to mean that while the box is closed, the system simultaneously exists in a superposition of the states "decayed nucleus/dead cat" and "undecayed nucleus/living cat", and that only when the box is opened and an observation performed does the wave function collapse into one of the two states.

A commonly held interpretation of quantum mechanics is the Copenhagen interpretation.  In the Copenhagen interpretation, a system stops being a superposition of states and becomes either one or the other when an observation takes place. This thought experiment makes apparent the fact that the nature of measurement, or observation, is not well-defined in this interpretation. The experiment can be interpreted to mean that while the box is closed, the system simultaneously exists in a superposition of the states "decayed nucleus/dead cat" and "undecayed nucleus/living cat", and that only when the box is opened and an observation performed does the wave function collapse into one of the two states.

是哥本哈根诠释是量子力学的主流诠释。根据哥本哈根诠释，当观测时，一个系统将不再处于叠加态，而是塌缩为其中任意一种状态。薛定谔的思维实验清楚地表明，在哥本哈根诠释中，测量或观察并没有被明确定义。实验可以解释为，盒子关闭时，系统处于“衰变的原子核 / 死猫”和“未衰变的原子核 / 活猫”叠加状中，只有打开盒子进行观测时，波函数才会塌缩成这两种状态之一。

量子力学的主流诠释之一是哥本哈根诠释。该诠释认为，一个系统在观察时将不再处于叠加态，而是坍缩为叠加态中的任意一种状态。薛定谔的思维实验清楚地表明，哥本哈根诠释没有明确定义测量和观察的本质。实验可以解释为，盒子关闭时，系统处于“衰变的原子核/死猫”和“未衰变的原子核/活猫”叠加态中，只有打开盒子进行观察时，波函数才会坍缩成这两种状态之一。

However, one of the main scientists associated with the Copenhagen interpretation, Niels Bohr, never had in mind the observer-induced collapse of the wave function, as he did not regard the wave function as physically real, but a statistical tool; thus, Schrödinger's cat did not pose any riddle to him. The cat would be either dead or alive long before the box is opened by a conscious observer. Analysis of an actual experiment found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before there is any conscious observation of the measurement, although the validity of their design is disputed. (The view that the "observation" is taken when a particle from the nucleus hits the detector can be developed into objective collapse theories. The thought experiment requires an "unconscious observation" by the detector in order for waveform collapse to occur. In contrast, ’’’<font color=”#32CD32”>the many worlds approach </font>’’’denies that collapse ever occurs.)

However, one of the main scientists associated with the Copenhagen interpretation, Niels Bohr, never had in mind the observer-induced collapse of the wave function, as he did not regard the wave function as physically real, but a statistical tool; thus, Schrödinger's cat did not pose any riddle to him. The cat would be either dead or alive long before the box is opened by a conscious observer. Analysis of an actual experiment found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before there is any conscious observation of the measurement, although the validity of their design is disputed. (The view that the "observation" is taken when a particle from the nucleus hits the detector can be developed into objective collapse theories. The thought experiment requires an "unconscious observation" by the detector in order for waveform collapse to occur. In contrast, ’’’<font color=”#32CD32”>the many worlds approach </font>’’’denies that collapse ever occurs.)

 

 

===Many-worlds interpretation and consistent histories===<br>

===Many-worlds interpretation and consistent histories===<br>

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.

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.

基于'''<font color=”#ff8000”>多世界诠释many-worlds interpretation</font>'''的量子力学“薛定谔的猫”悖论。按照这种诠释，每个事件都是一个分支点。无论盒子是否打开，猫都是既或者也死了，但“活着的”和“死了的”猫在宇宙的不同分支中，它们同样真实，但不能相互作用。

用'''<font color=”#ff8000”>多世界诠释many-worlds interpretation</font>'''解释量子力学“薛定谔的猫”悖论。多世界诠释认为每一个事件都是一个分支点。不管盒子是否打开，猫都是既活着也死了，但“活着的”和“死了的”猫在宇宙的不同分支中，同样真实但不能相互作用。

{{Main|Many-worlds interpretation}}

{{Main|Many-worlds interpretation}}

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 effective communication or interaction between them.

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 effective 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. The same mechanism of quantum decoherence is also important for the interpretation in terms of consistent histories. Only the "dead cat" or the "alive cat" can be a part of a consistent history in this interpretation. Decoherence is generally considered to prevent simultaneous observation of multiple states.

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. The same mechanism of quantum decoherence is also important for the interpretation in terms of consistent histories. Only the "dead cat" or the "alive cat" can be a part of a consistent history in this interpretation. Decoherence is generally considered to prevent simultaneous observation of multiple states.

 

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.

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.

The ensemble interpretation states that superpositions are nothing but subensembles 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 this interpretation state that this makes the Schrödinger's cat paradox a trivial matter, or a non-issue.

The ensemble interpretation states that superpositions are nothing but subensembles 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 this interpretation state that this makes the Schrödinger's cat paradox a trivial matter, or a non-issue.

'''<font color=”#ff8000”>系综诠释ensemble interpretation</font>'''指出，叠加态不过是一个更大的系综的子系综。态矢量不适用于单个的猫实验，而仅适用于许多类似准备的猫实验的统计数据。这种诠释的支持者认为，这使得薛定谔的猫悖论变得无关紧要，或者说是根本不是问题。

'''<font color=”#ff8000”>系综诠释ensemble interpretation</font>'''指出，叠加态不过是一个更大系综的子系综。态矢量不适用于单个猫实验，而仅适用于大量相似准备的猫实验的统计数据。该诠释的支持者认为，这使得薛定谔的猫悖论变得无关紧要，或者说根本不是问题。

This interpretation serves to discard the idea that a single physical system in quantum mechanics has a mathematical description that corresponds to it in any way.

This interpretation serves to discard the idea that a single physical system in quantum mechanics has a mathematical description that corresponds to it in any way.

The relational interpretation makes no fundamental distinction between the human experimenter, the cat, or 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. 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.

The relational interpretation makes no fundamental distinction between the human experimenter, the cat, or 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. 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.

'''<font color=”#ff8000”>关系诠释relational interpretation</font>'''认为人类实验者、猫或仪器之间，或者生命体和非生命体之间没有本质区别； 所有这些遵循相同的波函数演化规则的量子系统，都可以被认为是“观察者”。但是关系诠释允许不同的观察者根据他们所掌握的关于系统的信息，对同一系列事件给出不同的解释。猫可以被认为是仪器的观察者; 同时，实验者可以被认为是盒子系统（猫和仪器）的另一个观察者。在盒子被打开之前，根据活着或者死亡的状态，猫拥有关于设备状态的信息（原子已经衰变或没有衰变) ; 但是实验者并不掌握这些信息。这样，在同一时刻两个观察者对盒子的状态有不同的描述： 对猫来说，仪器的波函数“坍缩”了；对实验者来说，盒子系统仍然处于叠加态。直到盒子被打开，两个观察者对所发生的事情都掌握了同样的信息，两个系统状态才似乎“坍缩”成为相同的确定结果，既猫活着还是死亡。

'''<font color=”#ff8000”>关系诠释relational interpretation</font>'''认为人类实验者、猫或装置之间，或者生命体与非生命体之间没有本质区别；所有这些遵循相同波函数演化规则的量子系统都可以被认为是“观察者”。但是关系诠释允许不同的观察者根据掌握的不同盒内系统信息，对同一系列事件给出不同的解释。猫可以被认为是装置的观察者；同时，实验者可以被认为是盒内系统（猫和装置）的另一个观察者。在盒子被打开之前，根据自身的死活，猫拥有关于设备状态的信息（原子要么已经衰变要么没有衰变）；但是实验者并不掌握这些信息。这样，在同一时刻两个观察者对于盒子的状态有不同的描述：对猫来说，装置的波函数“坍缩”了，对实验者来说，盒内系统处于叠加态。直到盒子被打开，两个观察者对所发生的事情都掌握了同样的信息，两个系统才“坍缩”为同样一个确定结果，既猫不是活着就是死了。