# Physicists: Am I saying the right thing about Schroedinger's Cat? **URL:** \ **Category:** Factual Questions\ **Created:** [March 19, 2010, 10:50pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075 "2010-03-19T22:50:02Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Cheshire\_Human](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)\ **Post date:** [March 21, 2010, 7:34pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/41 "2010-03-21T19:34:14Z")
> [@Indistinguishable](#): > > Only… I am not a physicist. Indeed, my level of scientific knowledge is at times embarrassingly low. Many people on these boards are physicists, and are good at explaining things to boot. Perhaps they should present the relevant results instead of me. But, if no one else steps forward, I’ll give my own slight understanding of the matter. The main thing is that I just want to see discussion of Schroedinger’s cat that actually touches on quantum mechanics, rather than merely the perfectly classical idea of an unknown in a box (albeit we could still philosophize in the latter case; we should just recognize that this is a discussion we could have orthogonal to the truth of quantum mechanical theory). The problem is that quanum mechanics can either be interpreted as ‘Schrodinger’s cat has experienced something I don’t’, or ‘I experience something the CAT don’t’, take your pick. PROVE that the experience is “bullshit” BY THE CAT’S POINT OF VIEW. Since you CANNOT prove or disprove my experience, SHOW me why your experience is more valid than mine… This is an appeal to epistomology, but even THAT can’t validate my experience, SO why should I accept that YOUR experience is more valid than mine?. The entire argument is solely to justify one person’s “so-called” “superior intellect” over yours. In other words, when people are advancing arguments like this, the proper response is not to question the argument, but rather to call “bullshit” on the entire line of argument. _E PUR, SE MOUVE_. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [March 21, 2010, 7:44pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/42 "2010-03-21T19:44:28Z")
> [@Cheshire\_Human](#): > > arguments like this Arguments like what? ---
**Author:** ![Cheshire\_Human](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)\ **Post date:** [March 21, 2010, 7:58pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/43 "2010-03-21T19:58:44Z")
> [@Indistinguishable](#): > > Note that the mere idea of a situation where one does not know whether a cat in a box is dead or alive, and the question as to whether or not, till this veil of ignorance is lifted, the cat should be considered as having a definite state or instead as merely being in some kind of superposition, etc., have nothing intrinsically to do with the empirically discovered theory of quantum mechanics; in themselves, these are simple philosophical topics which could well be explored regardless of whether or not particular scientific experiments ever came out one way or another. Much popular discussion of quantum mechanics never gets beyond these sorts of vagaries. Unfortunately, this means much popular discussion of quantum mechanics never actually discusses quantum mechanics, per se, at all (perhaps because people are shy to speak of mathematical details? But to avoid mentioning math entirely is to avoid mentioning the actual relevant scientific laws/theories; and if one never discusses these, then whatever one is doing, it’s got nothing to say about or do with the science of the matter at all). Let us not be like that. Let us actually introduce some specific details which are characteristically quantum mechanic. Let us actually review some brute experimentally discovered results, which had they turned out differently would not have caused us to adopt quantum mechanics as a physical theory. Noncommuting observables, destructive interference, violations of Bell’s inequality, whatever the relevant results are, and why they are relevant. I don’t know where you got this (unless it WAS Shcrodinger,), but this is a much better translation of Schrodinger’s work than I could have come up with, myself, or have ever seen. Yes, I agree. On THIS we will argue, or we won’t argue at all… ---
**Author:** ![Cheshire\_Human](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)\ **Post date:** [March 21, 2010, 8:05pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/44 "2010-03-21T20:05:34Z")
> [@Frylock](#): > > Arguments like what? Precisely. Arguments like WHAT? E pur se mouve…? ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [March 21, 2010, 10:36pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/45 "2010-03-21T22:36:27Z")
> [@Cheshire\_Human](#): > > \ _E PUR, SE MOUVE_. 🆒 Nice, that. A little presumptuous, but what the hell, why not. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [March 21, 2010, 10:44pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/46 "2010-03-21T22:44:10Z")
> [@Leo\_Bloom](#): > > 🆒 Nice, that. A little presumptuous, but what the hell, why not. On the other hand, I can’t figure out what it’s significance is supposed to be in this discussion. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [March 21, 2010, 10:47pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/47 "2010-03-21T22:47:56Z")
Hey, man, I knew this cat, see, who was a real cool cat, y’dig? Like Coltrane, like…played live jazz all night, but was dead by the time the sun came up. His name was Schrod…Schroed…Shro…Shraeder! That’s it! Hey, man, want a toke of this dynamite shit? ---
**Author:** ![tim314](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tim314/32/3468_2.png) [@tim314](https://boards.straightdope.com/u/tim314)\ **Post date:** [March 21, 2010, 11:35pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/48 "2010-03-21T23:35:47Z")
If |Alive\> and |Dead\> were really pure quantum states and you could really and truly have a cat that was in the state |Alive\> + |Dead\>, then it would be correct to say “The cat is in a state in which a measurement of its aliveness has a 50% chance of finding that it is alive, and a 50% chance of finding that it is dead.” But _before_ the measurement is made it is not in a state of definite aliveness, so the question “Is this cat alive or dead” is not a meaningful one. Likewise, a wave can occupy lots of points at once – so it doesn’t make much sense to point at two of those points and say “Is the wave at this point or that one?” Much (not all) of the confusion in quantum mechanics comes from imagining that something is a classical particle with a single definite position and momentum, when in fact it isn’t . . . likewise Schrrödinger’s cat isn’t a classical cat with a single definite aliveness, even if, in fact, all real cats you’re ever likely to encounter are for all intents and purposes classical. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [March 22, 2010, 2:00am UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/49 "2010-03-22T02:00:01Z")
> [@Frylock](#): > > I could be wrong, but I was pretty sure that things’ being in superposition or not is _not_ observer relative. Would enjoy seeing a cite about it though. For me, it seems a logical outcome from the fact that we are all composed of quantum particles, hence subject to quantum mechanics. The cite below is from [Relational Quantum Mechanics](http://plato.stanford.edu/entries/qm-relational/#View) at the Stanford Encyclopedia of Philosophy. It says it’s copyright the Metaphysics Research Lab, so I’d like to find a better cite, especially one that isn’t for a single interpretation of QM, but no luck so far. On the other hand, I also haven’t found any cite to the contrary. If anyone knows of a rigorous cite either way, let me know. > [@Stanford Encyclopedia of Philosophy](#): > > What appears with respect to [a measuring system (observer)] O as a measurement of the variable q (with a specific outcome), appears with respect to [a second observer] O′ simply as the establishing of a correlation between [a measured system] S and O (without any specific outcome). As far as the observer O is concerned, a quantum event has happened and a property q of a system S has taken a certain value. As far as the second observer O′ is concerned, the only relevant element of reality is that a correlation is established between S and O. This correlation will manifest itself only in any further observation that O′ would perform on the S+O system. Up to the time in which it physically interacts with S+O, the system O′ has no access to the actual outcomes of the measurements performed by O on S . This actual outcome is real only with respect to O (Rovelli 1996, pp. 1650-52). ---
**Author:** ![Cheshire\_Human](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)\ **Post date:** [March 22, 2010, 3:53am UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/50 "2010-03-22T03:53:26Z")
> [@Frylock](#): > > On the other hand, I can’t figure out what it’s significance is supposed to be in this discussion. Google “Galileo”. The quote itself (it’s actual dictionary meaning) is meaningless in this discussion. My using it was a(n) historical reference to the entire “Galileo vs. THE CHURCH” episode. _ **I** _ don’t speak/read/understand middle-ages Italian, and so assume the translations of it I’ve seen are reasonable, but my use of it, here, was NOT to mean _literally_ what he meant when he said it, but to express the same “I don’t give a crap what you think about what I said. The damn Earth still moves!” attitude (or CATtitude, given the “Schrodinger’s Cat” point of this thread) that he meant when he said it. Go look at all the posts after mine. _ **Some** _ people got it… ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [March 22, 2010, 8:25pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/51 "2010-03-22T20:25:30Z")
**Indistinguishable** said: > [@](#): > > (perhaps because people are shy to speak of mathematical details? But to avoid mentioning math entirely is to avoid mentioning the actual relevant scientific laws/theories; and if one never discusses these, then whatever one is doing, it’s got nothing to say about or do with the science of the matter at all). Very few people understand math by itself, can grasp what it means and all the ramifications. Examples are used to translate results into meanings - concepts, illustrations, demonstrations, etc. Of course, these can easily be flawed. ---
**Author:** ![Cicero](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cicero/32/3594_2.png) [@Cicero](https://boards.straightdope.com/u/Cicero)\ **Post date:** [July 6, 2010, 1:24pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/52 "2010-07-06T13:24:55Z")
I wonder if someone an answer this without doing my head in. ---
**Author:** ![willthekittensurvive](https://avatars.discourse-cdn.com/v4/letter/w/91b2a8/32.png) [@willthekittensurvive](https://boards.straightdope.com/u/willthekittensurvive)\ **Post date:** [July 6, 2010, 1:39pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/53 "2010-07-06T13:39:34Z")
and what was wrong with using guinea pigs again? ---
**Author:** ![Cicero](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cicero/32/3594_2.png) [@Cicero](https://boards.straightdope.com/u/Cicero)\ **Post date:** [July 6, 2010, 1:42pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/54 "2010-07-06T13:42:00Z")
I think you have a vested interest though. ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [July 7, 2010, 1:56pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/55 "2010-07-07T13:56:51Z")
I am not a particle physicist, but here is a summary (as I see it) … Schrödinger saw a problem with the Copenhagen interpretation of quantum mechanics, as applied to macroscopic objects. The Cat thought experiment was intended to illustrate this problem. Schrödinger felt that it had to be obvious to everyone that at the end of the experiment, the cat was either alive or dead, and could not be in a superposition \ - it was a macroscopic object, and could not be in a superposition. The **Copenhagen interpretation** indicates that the superposition collapses on observation (whatever _observation_ means). The **Many Worlds theory** believes that the universe splits in two, one stream where the collapse goes one way, and one where it goes the other. We just exist in one of those streams and there is no way to connect with the other stream, and history is consistent. The **Ensemble interpretation** indicates that there is no isolation in the state of the experiment - the final collapse is governed by a larger state function that we cannot determine. 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 _observes_ the event (and lives or dies) but the human only observes the cat+box system, whose state does not collapse until they observe the state of the cat. Finally, in the **Objective Collapse theories** , superpositions are destroyed spontaneously (irrespective of external observation) when some objective physical threshold (of time, mass, temperature, irreversibility, etc.) is reached - the environment observes the cat (or the cat observes itself). The situation (illustrated by the recently designed oscillator) is that the macroscopic limits of what we can determine to be in a quantum state is slowly increasing. A subatomic particle is easy to imagine as having a quantum state that can collapse (as observed via the double-slit experiment, for photons, electrons and neutrons). However, a buckyball (fullerene, C[sub]60[/sub]) is a much more massive object than a subatomic particle, and can be made to interfere via the double slit experiment. The new oscillator is almost naked eye visible (i.e. macroscopic) but still can exhibit superposition (not while being observed, but it does exhibit the appropriate behaviour). All this challenges the assumptions about what constitutes _observation_ and allows probing of the nature of how and when the quantum collapse happens. Researchers will continue to build quantum machines that push this limit - both for research into quantum mechanics and to further quantum computing. Si ---
**Author:** ![Cicero](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cicero/32/3594_2.png) [@Cicero](https://boards.straightdope.com/u/Cicero)\ **Post date:** [July 7, 2010, 1:59pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/56 "2010-07-07T13:59:54Z")
I think you missed the part in my post about “without doing my head in”. I’m not even certain in what language you composed your reply 🙂 ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [July 7, 2010, 2:07pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/57 "2010-07-07T14:07:26Z")
> [@Cicero](#): > > I think you missed the part in my post about “without doing my head in”. > > I’m not even certain in what language you composed your reply 🙂 **Kiwi** 😉 bloody aussies. Si ---
**Author:** ![Cicero](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cicero/32/3594_2.png) [@Cicero](https://boards.straightdope.com/u/Cicero)\ **Post date:** [July 7, 2010, 11:27pm UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/58 "2010-07-07T23:27:12Z")
Bloody dumb Aussie if you must. 🙂 ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [July 8, 2010, 7:21am UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/59 "2010-07-08T07:21:50Z")
Here is a link that may help :- I haven’t had time to review this, so YMMV… [Bureau 42](http://www.bureau42.com/view/6841/summer-school-2010-1-quantum-physics) Now, my attempt… The [Double-Slit experiment](http://en.wikipedia.org/wiki/Double-slit_experiment) illustrated the problem that had arisen for early physicists - namely, was a photon a particle or an electromagnetic wave. If you have a light source and a single slit, you get a diffraction pattern, as if there was a wave. With two slits you get an interference pattern, again consistent with a wave. However, if you just send a single photon (a quantum particle) through the experiment, and repeat it several times, you still see the interference pattern - the single particle somehow interferes with itself. This dual nature of quantum particles was confusing, and the Copenhagen Interpretation gained credence - the particle had a probability of being in one of two quantum states (superposition), but any attempt to _observe_ the state caused it to collapse into the final state. Schrödinger felt that this could not be so in the case of macroscopic objects (real physical objects, not quantum particles), so he challenged it with his thought experiment. A quantum event (the possibility of the decay of a radioactive atom) controls a macroscopic object (the life of a cat) - since we know in the real world that the cat has to be either alive or dead (i.e. not in an \ superposition), the Copenhagen interpretation has to be wrong at some level. Other people have come up with alternative approaches to the Copenhagen Interpretation to avoid these problems, as I mentioned earlier. Does this help (at least initially)? Si ---
**Author:** ![clairobscur](https://avatars.discourse-cdn.com/v4/letter/c/839c29/32.png) [@clairobscur](https://boards.straightdope.com/u/clairobscur)\ **Post date:** [July 8, 2010, 9:14am UTC](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075/60 "2010-07-08T09:14:51Z")
> [@ZenBeam](#): > > There can be multiple observers, some in superposition relative to others. From the point of view of the cat, it’s an observer, and definitely alive or dead. Still, from the point of view of an observer outside the box, the cat is in a superposition. I’ve an issue with that. Let’s suppose you replace the cat by me. As an observer, and a lucky one, I happen to note that the atom didn’t decay and that I’m still alive. But at the same moment, for you, I’m still in superposition. You then (say, two seconds later) open the box to collapse the function and notice that I’m in fact dead. So, am I dead or alive, and when does the function collapse? At different times for you and me? Do I keep going in a world where I’m alive while you’re attending my funerals in your own world? [Previous page](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075.md?page=2) [Next page](https://boards.straightdope.com/t/physicists-am-i-saying-the-right-thing-about-schroedingers-cat/533075.md?page=4)