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B Wave function & Factorization

  1. Jan 19, 2016 #1
    In interpretations without natural factorizations, the cat won't just be dead or alive. It won't even be a cat. So let's say the cat is isolated in a box totally shielded from any decoherence from any environment.. and the any factorization between system and environment inside the box is suppressed.. what would become of the cat? just a blob or without any form? Would it's brain still work even if it's not a classical brain but totally composed of wave function without any factorization? How can you imagine, visualize or think of dynamics of wave functions without factorization and without any collapse?
     
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  3. Jan 19, 2016 #2

    A. Neumaier

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    It will die very quickly due to suffocation.
     
  4. Jan 19, 2016 #3

    bhobba

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    That's incorrect.

    Any interpretation contains the QM formalism. And from that formalism alone deoherence occurs and the cat is dead or alive.

    Don't be confused by the factorisation issue - it's not what some make it out to be. Its not that a quantum system cant be factored into cats etc, its that decoherence MAY depend on that factorisation. As yet theorems are lacking to decide the issue one way or another. It's a very fringe issue - and for good reason - similar assumptions are made in many areas of physics and it would be silly to think that are all 'wrong'. I remember one discussion on it where it was shown even classical mechanics has the problem - but few would doubt that branch of science in its domain of applicability.

    Thanks
    Bill
     
    Last edited: Jan 20, 2016
  5. Jan 19, 2016 #4

    bhobba

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    Just to elaborate a bit further things like cats etc gain their classicality from interaction with the environment. Remove that environment and they would not even be alive - the biochemical processes simply can't exist.

    Thanks
    Bill
     
  6. Jan 19, 2016 #5

    jfizzix

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    If the environment inside the box is completely decoupled from the environment outside the box, then that only means that the cat in the box is totally independent of the environment outside. Before its air runs out, it wouldn't know anything weird is going on, other than that it's stuck in a box.

    Our (on the outside) best estimate of what's going on inside the box is our knowledge of the quantum state of everything inside the box, and our knowledge of the equation of time evolution for the environment inside the box given by the total energy and interactions of all particles inside. Putting all that together, we can get some unusual estimations, like that there's a state that containes both live-cat and dead-cat possibilities, but just as we will only ever see one of these possibilities when we look inside the box. we can imagine the cat only experiences one of these possibilities as well.

    This too, is a matter of interpretation.
     
  7. Jan 19, 2016 #6
    For sake of discussions. Supposed there were no factorizations of any kind and the cat has no classical correlates and composed of pure wave function. How would the cat behave? Or let's take the case of simple particles. What would happen if the electrons had no factorizations of any kind.. how do you characterize the electrons? Or are wave functions and factorizations always go together. I was then asking what if you separate them.
     
  8. Jan 19, 2016 #7

    bhobba

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    How do you know you have a cat in there if the system hasn't been factored into cat and rest of the set-up? In Schroedinger's Cat you have precluded no factorisation by the very set-up of the experiment.

    With electrons you have precluded they cant be factored into electrons and the rest by discussing electrons in the first place. They are excitations of the electron field and that field is everywhere.

    It like the immovable object meets the irresistible force - its a non-sense statement because the universe cant contain both by the definition of the terms used.

    Thanks
    Bill
     
  9. Jan 19, 2016 #8
    Say you put a cat in the totally isolated box (with oxygen). And you suppress the bohmian natural factorization of position. What would happen to the cat. Would it just vanish physically?". If you can weaponize this. Then aim the factorization suppressor gun at any object and it can vanish. Wouldn't it.
     
  10. Jan 19, 2016 #9

    bhobba

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    You cant do that in the BM interpretation - objects have well defined positions and momenta at all times.

    But outside that interpretation say in the Ignorance Ensemble Interpretation - a cat is put in the box - you have factored it into the cat and the rest of the box by its very set-up. It always remains a cat as classical objects do. It simply dies of suffocation when the oxygen runs out or from being entangled with the radioactive source - whichever comes first. Everything in the box still remains classical.

    The very set-up of Schroedinger's Cat precludes your issue. You can't have a system factored into cat and other things then assume it cant be factored - its a logical absurdity. Now if you want to discuss if the cat being dead or alive happens if you factor it differently in your analysis - that is the factorisation problem and as yet we do not know the answer.

    Now if you were to truly isolate the box from the environment, and I mean actual isolation - even deep space has CBMR photons floating about - then you would likely have some very very strange effects like what happened with a tuning fork:
    http://www.scientificamerican.com/article/quantum-microphone/

    But observing such a situation to determine what's happening has me beat - since that will require interacting with it which you cant do if its isolated. I suspect that's where what Jfizzix said comes into play.

    Thanks
    Bill
     
    Last edited: Jan 19, 2016
  11. Jan 20, 2016 #10
    Factoring it is what chooses the position basis in the case of location of the cat. Won't it be possible for the cat to exist as pure wave function without collapsing into any position eigenstates? I guess collapse and factorization occur at the same time, so without them, you have pure wave function. And I'd like to imagine how a cat would behave if it is pure wave function. How can it tell its paws from its stomach for instance?
     
  12. Jan 20, 2016 #11

    bhobba

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    Incorrect.

    Decoherence does that.

    Thanks
    Bill
     
  13. Jan 20, 2016 #12
    Ok. In interpretations where the wave function has ontological existence. Is it possible for the cat to be composed of wave function without any collapse? This is in contrast to ensemble where it has classical permanence. The former has extra prediction not possible in the latter, the extra prediction that you can uncollapse objects and make it exist as wave function only. If so, how does it feel to be wave function only.
     
  14. Jan 20, 2016 #13

    bhobba

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    No. Because of decoherence the position basis is singled out and its in a mixed state of position. The technical reason is because most interactions have radial symmetry - the detail can be found in:
    https://www.amazon.com/Decoherence-Classical-Transition-Frontiers-Collection/dp/3540357734

    Thanks
    Bill
     
  15. Jan 20, 2016 #14

    bhobba

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    Entangled objects cant be in a pure state by the definition of a pure state. The whole system can be - but the entangled subsystems cant. Observationally they are in a mixed state.

    Now a cat must breathe air - its entangled with the air molecules so cant be in a pure state.

    Thanks
    Bill
     
  16. Jan 20, 2016 #15
    In intepretations where the wave functions are ontological (Not Ensemble but maybe Quantum Darwinism). Can you think of any experimental setup where you can totally isolate an object like a marble and suppress the position basis by turning it into momentum eigenstates. I'd like to see the object vanishing from physical world. Theoretically is there a way to do even if our present technology is not yet sufficient for this experiment, but possible in say 100,000 A.D.?
     
  17. Jan 20, 2016 #16

    bhobba

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    No. We technologically cant totally isolate an actual object from everything - eg we would have to suppress all stray vibrations somehow.

    Maybe sometime in the future but not now.

    When you do that what will happen will depend on the total set-up like with the tuning fork.

    But as technology progresses and we get closer and closer to that expect some strange things to emerge - but without the exact set-up knowing exactly what that is is not possible.

    And some vague general set-up is not good enough - you must be exact. And being exact with future technology is impossible otherwise we would have the technology now.

    Thanks
    Bill
     
  18. Jan 20, 2016 #17
    [
    Supposed you were inside a hypothetical box that can isolate against any CMR or even gravity, etc.. your whole body can be said to be the whole system itself and hence you are in pure state. But your head as subsystem is in mixed state. Yet your whole body is purely wave function only (pure state). Is this an accurate description? Supposed there were no collapse. Would your head as subsystem be in mixed state? Or without collapse, would the entangled subsystems still be in pure state? I plan to write a book of cartoon guide to decoherence and other matters that doesn't use any math but verbal summaries for laymen and need to understand some basic to avoid mistakes. Thank you.
     
  19. Jan 20, 2016 #18

    bhobba

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    Thanks
    Bill
     
  20. Jan 20, 2016 #19
    Or let's not use any actual example. I just want to be acquainted with the basic. I read some books already and need a few clarifications of some points. For a pure state.. would it turn into mixed state if there was no collapse of any kind? Would entangled subsystems be in mixed states if there were no collapse?
     
  21. Jan 20, 2016 #20

    bhobba

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    Collapse is not part of the formalism of QM.

    But basically decoherence leads to apparent collapse which is collapse for all practical purposes. I cant explain the difference at the lay level. If its entangled then, roughly, it has collapsed.

    Thanks
    Bill
     
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