Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What is it like for Schrödinger's Cat?

  1. Mar 11, 2010 #1
    I can't loose the feeling that physicists in general are a little anthropocentric in their understand... interpretation of the world - especially when it comes to "observing" Q.M. This has made me ponder about what perspective the cat in that famous experiment has.

    Unless we open the box, and thereby determine the state of the system, we can have no knowledge about the inside and thus to us the cat is dead or alive in equal probabilities. But since the system is completely detached from the outside, the cat too is trapped in its own reality and could aswell assume that the world has been blown to pieces. Unless it opens the box, it will never know.

    The essential statement in this experiment is that there are many realities in that box, and we will only get a random one, when we look at it - what reality we are likely to get, is determined by probability.

    What am I getting at? I'm saying that this experiment is utter nonsense and completly beneath any physical standard.

    So the cat is in there with its realities and we are outside with ours. Besides there is a marginal chance of the cat taking initiative and opening the box. But unless we open the box, we will never know whether the cat is opening the box from the inside?

    We are getting there, Schrödinger.

    So cat's perspective, atom doesn't decay. Cat surives. Cat opens box and comes out to a reality where the world has been sucked into a black hole at CERN (marginal chance of that happending from the cat's perspective, too). We are outside. Open the box after 2 hours. Cat is dead.

    Where the heck is that cat?

    Did it clone itsself and travel to another dimension and left it's dead clone behind for us to find?

    Disclaimer: Don't answer me with "your understanding of Q/M is utterly flawed, I can't help you", just because you are not capable of replying to the actual matter. I was granted this experience with just the last question I asked here about G/R. If you are of that ilk and are not readily willing to dive into a discussion about something you cannot look up in your favorite textbook: , to put it in internet terms.

    Yes, this doesn't require partial derivatives nor exponential functions nor gaussian distributions and it's Q/M nonetheless and the Copenhagen Interpretation is an Interpretation - something that can be discussed in more casual terms.

    So please, go ahead: Where did the cat go?
     
    Last edited by a moderator: Mar 12, 2010
  2. jcsd
  3. Mar 11, 2010 #2
    If you can't "loose" the feeling, perhaps you could tighten it instead?
     
    Last edited: Mar 11, 2010
  4. Mar 11, 2010 #3

    SpectraCat

    User Avatar
    Science Advisor

    Your interpretation is correct, provided that the box is made of some theoretical stuff that prevents any information at all to pass through it.

    Nothing in any interpretation of QM suggests our point of view is any more valid than the cat's. The many-worlds interpretation of QM , as far as I understand it, in fact allows for the situations in your example to occur.

    So I guess I don't see the problem ...
     
  5. Mar 11, 2010 #4
    That "loose" really must have drawn the last bit of attention from you. After that it was all over with your interest in the actual text - a blue car, eh? :biggrin:

    @ 1st Poster

    Well, I think although this is somewhat disappointing I couldn't ask for a more satisfying answer, either. Therefore thanks.

    @ 2nd Poster
     
  6. Mar 11, 2010 #5
    I've never seen the cat experiment turned inside out like this. Nice.
     
  7. Mar 12, 2010 #6

    JesseM

    User Avatar
    Science Advisor

    Take a look at the [URL [Broken] friend thought-experiment[/url] which similarly tries to consider things from the perspective of the individual "inside the box".
     
    Last edited by a moderator: May 4, 2017
  8. Mar 12, 2010 #7
    Thank conway, you encouraged me to put a little more thought into this and after I read the first paragraphs of that Wigner Friend experiment, I feel like I have to add something to my "too anthropocentric viewpoint" statement, because Wigner seem to strugge with that very problem.

    I'd like to take the human observer out of the experiment. What reads "Quantum State is superposed unless determined by the observer" should be something else to prevent misconceptions one is easily to tempted to have with this kind of formulation. I'm going to explain:

    Let's for one second reduce and shrink the observer to an atom. A life-form, fully deterministic in this case to not to complicate things -- we can think about what happens if the observer itsself is subjected to quantum uncertainty --, and completly simple, yet conscious and able to conduct the experiment.

    We are an atom, or, if you struggle with that, a bacterium for this sake. Eventually, atom, bacterium, it really doesn't matter. Even the atom can be split into smaller parts, clearly each component, on each scale, is separately and individually subjected to Quantum Incertainty.

    The cat remains a cat, let's call it "Cat". For a new experiment we put another cat, named "Other Cat", to memorize them better, in the box with Cat. We could also use the already present flask for that matter, but imagining another cat in the box with Cat is nicer, because Cat isn't so allone then.

    We are still one atom, bacterium respectively outside the box. Once the lid is opened, the information from within the box propagates with the speed of light in all directions from the slit of the just-opened lid (the lid, while opened, is still a barrier to everything in the universe).

    To draw a simpler picture let's image we would keep the lid closed for so long that Cat and Other Cat, normally beautiful red fur, if killed, would start to rotten so they would be green when we open the box.

    Red and green photons travel from opening in all directions. Red and green photons are actually just a component of the realities that propagate. The very second these realities reach us, the atom, with which the components of the realities can interact, our atom is drawn - linked with - one of the realities.

    I think the latter is the hardest part to actually internalize. It's not the observer (atom) who determines which reality is actually inside the box. It's the reality that "chooses" it's observer with equal right. The green photons, because they too can be given equally justified viewpoints, find their observer as well as the red ones do. One might see a more philosophical problem to this, namely "are it the same photons" but as with "is the atom the same atom it was before" we can easily evade this problem by just making descriptions from each perspective separately, flowing through time with the "observers" and not trying to get into a time-free position.

    The atom is coupled to one of the instantaneous realities. It is, so to say, in a constant random fluctuation between an infinite choise of realities which are all possible consitutions the world could be in, this and the very next moment. The choice which reality it goes into is determined by how probable the specific reality is. And while it goes into a 50% likely reality of green photons, it equally travels into a reality with red photons. The two realities with the atom inside, with an infinite number of others, coexist at any time.

    It's a ludicrous picture because where at first, Quantum Mechanics appear take the determination away from the world, it eventually takes away the meaning from determination. Eventually, it even takes away the meaning from propagation through time and time itsself!

    Scrap what I said about being coupled to a reality. It moves throught realities as little as it moves through time: Not at all. I equally exists in all the realities. And in some realities it doesn't even exist because it's components do not exist or are in a different configuration.

    When we drop a stone, assuming that it's determined to hit the ground and feel confirmed because it does, we only do so, because "we" are the "we" in the reality where it hits the ground. There is a reality where a Jumbo-Jet in low fly-by catches the stone and we wonder about what the chances were, that this would happen and drop another stone, just to prove, that Jumbo-Jets don't prevent the determined from happening.
    Equally well, there is a reality in which we never dropped the stone in the first place.

    So what does it mean, when I press the key "k" on my keyboard? In some way, it's not determined because I'm subjected to uncertainty - on the other hand it's absolutly sure that I will have pressed the key, because there exists a reality where I do and if it's not "me" doing it, it's still happening. Strange. Let's go back to the cats that have been in the box for quite a while now and apply this confusing philosophical framework we just established.

    At the moment we open the lid, both realities are superposed and it's not yet determined which we will see. A split second later, we will know. What we will practically know, though, is which reality we are in, not which reality is in the box.

    Other Cat sits closer to us than Cat, the information of Other Cat will thus reach us before the information of Cat will. A collegue however, is standing at the opposite side of the box, closer to Cat. The information about Cat'S well-being will thus reach him before the one of Other Cat.
    Once the information about Other Cat reaches us, we will know the state of Other Cat in our instantaneous reality. Neglecting the probability that Cat built itsself a shelter to the poison from Other Cat's remains and thereby outruling a set of realities, we know the state of Cat, before the information of Cat reaches us.

    That's not because the red or green photons become either red or green in the middle of their flight when the photons from other Cat reach us. It's because we are in a reality where all the photons are either red or green - and we know what reality we are in since we saw the photons coming from Other Cat. They are highly probably (unless Cat built its shelter) "entangled" in frequency because of causal limitations.

    Both, Other Cat and Cat survived our attempted murder.

    The first information on the situation or collegue receives is the one from Cat. It reaches him before information of Other Cat and information of our disappointment or relief. At that moment, everything is possible and, to his bewilderment, Cat didn't make it. One might ask, how this can possibly be - how can our collegue get trapped in such a disturbing reality where scientists kill cats for their amusement while we feel no regret at all?

    Let's get one step back again and modify the box, so either the cover at our collegues side, or the cover at our side can be lifted, but not unless a barrier between the two cats is inserted. With everything closed, our collegues situation with the situation of the two cats is a superposition of happy and sad. Once we open our side of the cover, we find ourselves in either of the realities. From the perspective of dead Cat, our collegue opens the cover. Dead Cat and sad collegue are in the same reality. Alive Other Cat and happy us are in another.

    I think the clue is to think of uncertainty as an infinite amount of distinct realities ("dimensions") and NOT to assume a constant flux foward in time. When the atom moves through time, it's just lucky to exist in all these realities which differ in a way, that the impression of coherence arises.
     
  9. Mar 12, 2010 #8
    As JesseM said, this isn't a new idea, but has been explored in Wigner's friend. The rest... it is now clear that your aggressive stance in the beginning is a result of the fact that people have told you many times that you DON'T have a clear understanding of QM. The thing is.. you don't. You've combined concepts from a number of theories, and smashed them together into something that apparantly makes more intuitive sense to you than QM formalism.

    By the way... you do realize that photons don't have colour, or colour charges (as in QCD)? Light has a wavelength which corrosponds to a colour that we percieve (or not), in one of three ranges: Red, Green, Blue. That doesn't mean the world is just packed of RGB photons, it's just that we have only triple colour percpetion, with the rest taking place as a mental "trick" if you like, which our brains perform.

    As for the rest, I suggest that you do some heavy research on the HUP (yeah, btw.. it's UNcertainty, not INcertainty... proper noun, no excpetions), as well as thought experiments such as Wigner's Friend, Quantum Suicide and Immortality (both similar flaws in thinking to yours).

    As it is, you're just strugglign with the basic concept of superpositions and wavefunction collapse... fair enough. Lets talk about those scientific issues, and not rambling toy models which conform only to your VIEW of "reality".
     
  10. Mar 12, 2010 #9
    I'm not struggling with the "basic concepts", I'm trying to formulate them while remaining compliant to the predictions the model makes and the Copenhagen Intepretation of "many worlds" - from another perspective than the human-centered one. The Wave-Function collapse, for instance, can easily be seen in my description as the moment we face the "other world".
     
  11. Mar 12, 2010 #10

    Doc Al

    User Avatar

    Staff: Mentor

    Moderator's Note: This thread is being moved to Philosophy and reopened.
     
  12. Mar 12, 2010 #11
    The cat is not an important part of the puzzle it was probably just added to make it seem more interesting. The important thing to take from the thought expierment is that an event has a probility of happening and that untill it happens there is a chance it could turn out any way it can turn out. QM is basically just a shift from black and white thinking or at least thats what it hopes to be.
     
  13. Mar 13, 2010 #12

    Unmeasured quantum events are not real. At least as far as we are concerned.
     
  14. Mar 21, 2010 #13
    The reason the cat is included in the scenario is because the notion that a being can be simultaneously alive and dead is obviously nonsensical. Live / dead is more meaningful than black/white, since there is no possibility of 'gray.'

    Don't forget, Schrodinger's motive for devising the whole thing was to come up with an example contrasting the Copenhagen Interpretation and the macrosopic world.
     
  15. Mar 21, 2010 #14
    I think this is what goes wrong when you try to 'interpret' physics.

    You have some formulae and principles, they—within experimental boundaries—praedict what we empirically measure, that's all there is to know. I find it a hell of loss of headache when I don't try to get a 'conception' of it behind it, and just follow the maths like a slave.
     
  16. Mar 21, 2010 #15
    That would be the Instrumentalist/Shut up and calculate school of thought. I tend towards that, but with curiosity. I simply don't believe any current "Interpretation" of QM adds to the science, and the notion of a complete interpretation of an incomplete theory seems silly.

    Ah well.
     
  17. Mar 21, 2010 #16

    Pythagorean

    User Avatar
    Gold Member

    The cat was supposed to demonstrate the silliness of CI. It's actually kind of bad analogy and it only really pertains to the mathematical prediction model of undistinguishable particles.
     
  18. Mar 22, 2010 #17
    It's just a mathematical model for me that has a praedicting value, I wouldn't even call it 'explaining' any thing.

    Interpreting it as 'being at two places at the same time', or 'not yet having decided a place', whatever.

     
  19. Mar 22, 2010 #18
    One way to understand Schrodinger's cat is to get yourself garbagefaced with Absinthe. The question then becomes "where was I gone? ":biggrin:
     
  20. Mar 22, 2010 #19
    ..."And why does my mouth taste like Pine-Sol?!" :rofl:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: What is it like for Schrödinger's Cat?
Loading...