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Photon's age? consider two interacting photons in the EPR effect

  1. Mar 13, 2008 #1
    consider two interacting photons in the EPR effect.

    the photons separate and move towards different detectors 1 km in each direction.

    measuring the first photon instantaneously affects the other photon.

    how much has teh first photon aged?

    how much has the second photon aged?
  2. jcsd
  3. Mar 13, 2008 #2

    Doc Al

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    Are you sure about that? How would you know?

    How would you define the "age" of a photon? According to whom?
  4. Mar 13, 2008 #3

    Aspect et al and several experiments have demonstrated Bell's inequalites and action-at-a-distance.

    Good question!

    Does a photon age?

    Suppose a battery-operated clock flew at 99.999999999999999999999999999999999999% the speed of light.

    When we decelerated the clock to rest relative to the lab frame, and took the batteries out so the hands woudl stop, would we all agree on the time read on the clock?
  5. Mar 13, 2008 #4


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    The violation of Bell's inequalities only shows the failure of local realism with unique outcomes, that's not the same as showing action-at-a-distance. For example, advocates of the many-worlds-interpretation argue that they can explain these results without violating locality, at the cost of disputing that any given measurement has a unique outcome.
  6. Mar 13, 2008 #5
    Hello Jesse,

    Do photons age?

    Also, if you're right, that would be great if you could add that information to the wikipedia page:
    http://en.wikipedia.org/wiki/Action_at_a_distance_(physics [Broken])

    Also, I think you could publish some papers updating this one:

    Rock on!
    Last edited by a moderator: May 3, 2017
  7. Mar 13, 2008 #6
    P.S. What are some of the famous experiments that have demonstrated the many-worlds that refute Aspect et al's experiments?
  8. Mar 13, 2008 #7
    Hello Jesse,

    You may also want to contact amazon.com and various publishers/authors and tell them that their books are wrong:

    I have those books sitting here and none of them say what you say.

  9. Mar 13, 2008 #8


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    It doesn't refute the experiment, it simply interprets the results in a way that doesn't conflict with locality (which is fine, because one of the necessary assumptions of a proof of Bell's theorem is that measurements have a single definite outcome, which isn't true in the many-worlds interpretation). If you're interested in references for the claim that many-worlds advocates think it can explain the results of these experiments without violating locality, this paper lists a number of them:
    And in this subsequent paper by the same author, I think he's arguing that the Everett interpretation of quantum field theory can also be understood in terms of information encoded in purely local operators.

    For a simple "toy" model of how we can violate one of the Bell inequalities without violating locality if we allow experimenters to split into multiple copies on each measurement, see my post #11 on this thread.
  10. Mar 13, 2008 #9
    Which experiments prove the many-worlds theories?

    How many worlds/flying spaghetti monsters would Everret suppose?

    What I like about Aspect's experiment is that it is real.
  11. Mar 13, 2008 #10


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    Pretty sure DrChinese would agree with my statements, although you can ask him, he posts here regularly. In post #36 in the thread I linked to above he says:
    I think, though I'm not sure, that when he says "it may be the case that the 'true' theory is local and non-realistic", and that "it is a popular (even if not the majority) interpretation of QM" in which QM is seen as "complete", that he's referring to the MWI.
  12. Mar 13, 2008 #11


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    I don't think you understand what an "interpretation" of QM means--they all are constructed to agree on predictions, so there's no experimental way to test any of them. See wikipedia's article on interpretation of quantum mechanics which lists a number of them. Any claim that QM involves FTL effects is itself dependent on your choice of interpretation (for example, it would be true in Bohm's interpretation).
  13. Mar 13, 2008 #12
  14. Mar 13, 2008 #13


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    No, does he address the possibility that measurements may have non-unique outcomes?
    Quantum entanglement has been seen, and the correlations predicted in entanglement have been seen (and the MWI would not dispute either prediction). But to call these correlations "FTL" requires certain assumptions about the interpretation of QM which are just as untestable as the assumptions made by the the MWI.
    It's you who has a problem with understanding the logic of Bell's proof if you think the entanglement experiments definitively prove FTL. It only proves that given certain assumptions, one of which must be the assumption of unique outcomes to measurements; the proof only tells you that all the assumptions cannot simultaneously be correct, it doesn't prove that some of them can't be correct (such as the assumption of locality) if others are incorrect (the assumption of unique outcomes, i.e. 'realism'). You don't have to accept that there's any real likelihood that realism is violated, but you do have to accept that the results of the entanglement experiments can't prove that it isn't, in which case the results could still be compatible with locality.
  15. Mar 13, 2008 #14
    You say, "Quantum entanglement has been seen, and the correlations predicted in entanglement have been seen (and the MWI would not dispute either prediction). But to call these correlations "FTL" requires certain assumptions about the interpretation of QM which are just as untestable as the assumptions made by the the MWI."

    What would I have to assume to call the correlations FTL?

    Numerous experiments have shown FTL correlations. What special assumptions are you assuming that they are assuming?
  16. Mar 13, 2008 #15


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    You'd have to assume that "realism" is correct, i.e. that each measurement has a unique outcome, instead of causing the experimenter to split into multiple versions which observe different outcomes. There's at least one other assumption you'd have to make too even if you accepted realism, namely the assumption that "superdeterminism" is false (see the discussion following ThomasT's post #57 on this thread). You'd also have to assume no backwards-in-time influences where the experimenter's choices can influence the state the two particles are created in, which would be violated in the transactional interpretation of QM (though depending on your point of view this may be a violation of locality, but I think the time-symmetry of the laws of physics makes it ambiguous whether locality is violated by a future event influencing an event in its own past light cone).
  17. Mar 13, 2008 #16

    Yes--I assume that realism is real and that backwards-in-time effects aren't.

    I think this is how Newton/Einstein/Bohr/Fermi/Dirac/Feynman/Heisenberg approached physics and relativity.

    Perhaps you don't take realism to be real. Now I understand your general dismissal of experiment in relativity and qauntum mechanics.
    Last edited: Mar 13, 2008
  18. Mar 13, 2008 #17


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    JesseM did no such thing. You have a problem with comprehension. Therefore, prolonging this thread is useless.

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