Talk:Schrödinger's cat

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Erwin Schrödinger described how one could, in principle, create entanglement of a large-scale system by making it dependent on an elementary particle 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. 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.

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I refuse to accept it

I don't care how many pretty diagrams you use, how many big-name scientists talked about it, or your expirements on atoms. A cat can NOT be alive and dead at the same time. If this article does convince someone that such a thing is possible, then we have a Lenin was a mushroom-type case on our hands. 217.100.32.162 (talk) 08:58, 21 June 2019 (UTC)

The point of the thought experiment was to present an absurd scenario. So, I'm glad you got that part. Now maybe you can learn why Schrodinger wanted to present an absurd scenario. -Jordgette [talk] 21:17, 21 June 2019 (UTC)

This article really does not make that point clear. There seem to be quite many people who believe that it has been seriously suggested that a cat might be both alive and dead at the same time. And it really doesn't help that many physicists reinforce this belief in their attempts to popularize quantum mechanics. Yuhani (talk) 16:05, 17 July 2019 (UTC)

I think the second sentence of the intro makes it clear, as do several other passages in the article. Can you think of any ways that such misunderstandings can be further reduced, without oversimplifying the concept or stripping it of its nuance? -Jordgette [talk] 17:05, 17 July 2019 (UTC)

Maybe I'm missing something ...

I feel like I'm not understanding something, or maybe I'm just accustomed to thinking in terms of statistical processes, and so I'm possibly an "ensemblist". I don't see the paradox in Schrödinger's cat experiment. It seems like it is a paradox *only* if one insists on trying to interpret quantum mechanics in a purely deterministic way. Otherwise, if one accepts the statistical nature of quantum mechanics, there is no problem that I can see. If this is the dichotomy, then perhaps the article can make this point more clearly. Attic Salt (talk) 15:15, 23 December 2019 (UTC)

It's not really a paradox. It's a paradox, of sorts, if you believe that superpositions can become wildly macroscopic — but the discovery of decoherence has put that to rest. And even without decoherence, the cat is an observer. For that reason I rather prefer "Einstein's powder keg" myself. -Jordgette [talk] 18:51, 23 December 2019 (UTC)

Yeah, as you say "paradox" is not totally accurate. @Attic Salt: The article doesn't go into detail much. It could probably be improved. The point of the experiment is: exactly when and where does wavefunction collapse occur? On an atomic scale, the wavefunction representing a particle can be in a superposition of states, it can have components representing the particle at different positions or states at the same time. In the Schrodinger experiment it is a radioactive nucleus; before they are observed, radioactive nuclei are in a superposition of an undecayed nucleus and a nucleus which has emitted gamma rays. In the experiment this particle in a superposition interacts with more and more other particles (the "outside world") in such a way that the two different possible states of the particle result in very different macroscopic states, a dead cat vs a live cat. The problem is, the Schrodinger equation is linear, so when a particle in a superposition interacts with (is entangled with) other particles, the result is to put them in a superposition too. But at the end of the process, when we open the box, we don't find a "superposition", but only one of the two states, live cat or dead cat. So the question is, at what point in the process does the superposition collapse into one or the other final state?

In the experiment, if the radioactive nucleus decays, the gamma ray released will enter the geiger counter tube and ionize the gas. Since the nucleus is in a superposition of decayed and undecayed states, the gas in the geiger counter should be in a superposition of ionized and unionized states. If the gas is ionized, it allows a pulse of electric current to pass into the geiger counter electronics, so the geiger counter electronics should be in a superposition of pulse/no pulse states. The geiger counter amplifies the pulse to a current which is applied to an actuator which releases a hammer which smashes the poison bottle, releasing the poison. Since the geiger counter is in a superposition, the poison bottle should be in a superposition of smashed/unsmashed states, resulting in a cat in a superposition of alive and dead states. Where in this process does wavefunction collapse occur, and how, and why? --Chetvorno^TALK 16:00, 24 December 2019 (UTC)

As Jordgette said, the process of decoherence provides a generally accepted explanation for apparent collapse; it says that when a superposition expands to the point where it entangles a large number of particles, the different component states stop interacting, become mutually unobservable, so we only experience the state we're in, dead cat or live cat. I don't really understand whether this means the other state doesn't exist, or whether it exists in another "state space" undetectible from ours (which I guess is the Many-worlds interpretation). --Chetvorno^TALK 20:17, 23 December 2019 (UTC)

@Jordgette: I didn't quite get your statement about the cat as an observer. From what I understand, the importance of the cat as an "observer" is not an issue. The idea that a living brain, cat or human, has some special ability in QM that is required to collapse a wavefunction ("consciousness causes collapse") is obsolete. "Observers" are made of atoms, and have the same ability as everything else to be in superpositions and experience wavefunction collapse. Whether a cat, a person, or a video camera, is in the box, it will record the same thing; only one of the two possible histories: "radioactive decay/released poison/dead cat" or "no decay/no poison/live cat" will be left afterwards. --Chetvorno^TALK 16:00, 24 December 2019 (UTC)

The idea of a cat being an observer comes from the relational interpretation, which is discussed in the article. See also Wigner's friend. -Jordgette [talk] 05:22, 25 December 2019 (UTC)

The Cat who didn't miaow

Hello and thank you for this page.

I've read the article and the comments on here, grasped 'the problem', acknowledge the intention -why the cat metaphor was employed, accept the various additional theories but something of the problem is (I respectfully submit) still not making it onto/into the page/article. It's an effort to expose how one method of recordng/observing a latent state is inadequate.

If the cat is/was used to accentuate or highlight the im-possibility of the cat being either dead or alive, but not both; then fine. That should be the end of it and the end to any discussion. -But, there seems more. What other outstanding issues are there?

It seems to me that in the correspondence between S and E, both seemed to know exactly what 'problem' they were referring to but/and so neither spelled it out explicitly. So, the employment of the cat metaphor solves 'the problem' that as the cat cannot be both dead and alive, observations regarding the method used to diagnose the state of the object are inadequate.

The value of the cat is (to me) to introduce a plot and a timeline whereby due to the imperceptible (to the eye) changes to the state of the object, any change in the object triggers a change in the cat. Fine. But, if this is the only value of the cat's presence, then S. is 'merely' critiquing the inadequacy of theory. The cat moves the scenario into reality and out of experimental musing. Fine. But is that all?

There seems to be a whole lot more which, as said, hasn't made it onto the page. And, if this is all, then what's all the fuss about. A schoolboy can grasp the inadequacy of any method.

I suspect, the problem is more profound and while not courting profundity, I think some effort should be made to delve deeper to identify just what that quandary is. I imagine it touches on the Heisenberg Principle where the role of the observer has an impact upon the thing observed but that, you'll agree, is a separate problem/issue not stated in the equation of the cat.

Another metaphor is required (I humbly suggest) if Shrodinger's Cat is to achieve its potential as a valuable critique on scientific method, one where the presence of a sentient being compromises the performance of an object, as in a store detective inhibiting shop lifting or speed signs inhibiting speeding. A better example might be a heart monitor which will not sound so long as the flow of oxygen to a patient is constant. Any deviation in the flow of oxygen to the patient triggers the monitor to sound an alarm. That seems closer to the issue as quite apart from (and independent of) the patient, the catalyst is non-organic. Either a malfunction in the equipment or a change in the patient's breathing may be responsible for the alarm.

So, beyond their agreement as to the inadequacy of the method, why were Ei. & Sh. aroused to the extent their correspondence reveals? Though possibly innovative in their day, their solution seems a commonplace now and yet Shrodinger's Cat lives on, so to speak though the cat has been well and truly flogged.

To finish; rather than search around for possible applications for their solution/discovery; Bishop Berkeleyan hypotheses on presence and absence, the role of the observer in experiments; Cartesian xy axes replaced/displace/improved by a Heisenbergian added Z factor to include the observer of X and Y, let's instead look to what theoretical quandaries typically elude perceivers and see if we can't work from the solution backwards. (My aplogies for presuming any of you have time for this). I will try to track down a better translation of their correspondence or other supporting clues as to the problem they were discussing.

Shrodinger's Cat seems only to have scratched the surface of a Novum Organon yet to be articulated. People, scientists included!, seem both to over- and under- estimate their presence as catalysts in all kinds of situations. A new method, an objective correlative (as TS Eliot called it) is needed to augment perception. Hope that doesn't sound too grand. Thanks. P.