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I Pseudorandom Entanglement and Special Relativity

  1. Jan 4, 2016 #1
    I was thinking about the superluminal speeds observed with quantum entanglement.

    Perhaps the particles are not really entangled, each of them just changes their spin with an in-built pseudorandom algorithm, allowing them to appear to be "in-sync" and thus entangled.

    This is just purely hypothetical.
     
  2. jcsd
  3. Jan 4, 2016 #2

    DrChinese

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    Hypothetical conjecture is normally not welcome for threads. What you are proposing, however, is the same question that is presented here frequently. That being: Could local hidden variables account for entangled pair statistics?

    The answer to that question is: NO. Please take a bit of time to read up on EPR (1935) and especially Bell's Theorem (1964), which concludes:

    No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics.
     
  4. Jan 4, 2016 #3

    Mentz114

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    Looks like a local hidden variable explanation which rules it out. I think this one is like the coincidence loophole and has been ruled out by experiments.

    [Dr C. beat me by seconds]
     
  5. Jan 4, 2016 #4

    DrChinese

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    Yes, but you beat me by seconds on the other thread. :)
     
  6. Jan 4, 2016 #5
    Did those experiments involve the concept of a pseudorandom generator?
     
  7. Jan 4, 2016 #6
    Can you elaborate Bell's theorem regarding pseudorandom generators? Thanks.
     
  8. Jan 4, 2016 #7

    DrChinese

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    A pseudorandom generator is simply a specific form of hidden variables. Bell's Theorem shows that any hidden variable theory is incompatible with the predictions of QM. You really need to understand Bell's Theorem before we can proceed further.

    Hint: pseudorandom generators (and hidden variable theories in general) CAN explain perfect correlation/anti-correlation of entangled particles when their spin is measured at the same angles. However, at other angles, it cannot do so.
     
  9. Jan 4, 2016 #8

    DrChinese

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    I might humbly suggest a page on my web site, which presents a simple proof of the theorem:

    http://drchinese.com/David/Bell_Theorem_Easy_Math.htm

    If you understand this, you will understand why no local (independently evaluated) algorithm can emulate QM. All local hidden variable hypotheses are either pseudo-random or purely random, by the way. They couldn't match the most obvious of observation otherwise.
     
  10. Jan 4, 2016 #9
    Oh I see.

    My mind is so torn.

    On the one hand, we have the de Sitter effect, which is IMHO one of the strongest evidences for Special Relativity. On the other hand, we are confronted with entanglement.

    Us not being able to send any meaningful information with entanglement doesn't placate it.

    What to do? :confused:
     
  11. Jan 4, 2016 #10

    DrChinese

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    Beauty is in the eye of the beholder, and so is one's view of SR and QM.

    Modern quantum field theory is relativistic. There is no significant contradiction between SR and QM. Physicists who work with particle accelerators every day (there are a number on this forum) use both without any worry. If they don't worry, I don't worry. :)
     
  12. Jan 4, 2016 #11

    zonde

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    Isn't de Sitter effect evidence for General Relativity?

    Anyways, you probably are mixing up Special Relativity (a physics theory) and the idea that Relativity principle is fundamental (assumption).
     
  13. Jan 5, 2016 #12
    The de Sitter effect for binary stars.

    Videos taken of binary stars very far away don't exhibit the dynamic lag that is to be expected if emission theory is correct.
    This proves that spacetime is Lorentzian, not Galilean.

    A superluminal signal in the case of entanglement suggests a superluminal reference frame, something that can't exist in the Lorentzian framework.
     
  14. Jan 5, 2016 #13

    vanhees71

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    I don't know what the de Sitter effect has to do with quantum entanglement, but the solution is very simple. Just use standard relativistic local quantum field theory which is among the most successful fundamental theories ever discovered. There is by construction no action at a distance, and indeed problems a la EPR with entanglement only come from the unnecessary assumption that there is a collapse of the state as a real process. There is no such thing within standard relativistic QFT, and thus we can live very well with an astonishing significance of violation of Bell's inequality as predicted by standard QFT, i.e., with the long-ranged correlations described by some entangled many-body (usually two-photon) states.
     
  15. Jan 5, 2016 #14

    zonde

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    It doesn't. Experiments don't prove anything.
    De Sitter experiment falsifies emission theory and confirms special relativity.
    Superluminal phenomena can coexist with relativistic particles if you take Relativity principle as effective, not fundamental.
     
  16. Jan 5, 2016 #15
    Do you know of any candidates for a superseding theory of flat spacetime involving superluminal reference frames?
     
  17. Jan 5, 2016 #16

    zonde

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    Lorentzian interpretation (LET) of special relativity is based on preferred reference frame so it can be easily extended with superluminal phenomena.
     
  18. Feb 3, 2016 #17
  19. Feb 3, 2016 #18

    zonde

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    I don't know of any (haven't looked for such articles actually). But I suppose it's too trivial to expect any.
    You just assume that one reference frame is special and describe any superluminal phenomena in that reference frame.

    I looked at the thread and the link in that thread. I don't know that no-go theorem mentioned in the article but of course one has to give up some symmetries of SR when introducing preferred frame.

    Btw have you looked at his thread https://www.physicsforums.com/threads/ftl-signal-and-causality.854757/?
     
  20. Feb 3, 2016 #19
    yeah the tachyonic antitelephone

    Idk, imaginary transverse space doesn't make sense to me.
     
  21. Feb 3, 2016 #20

    zonde

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    Neither to me.
     
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