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Entanglement and physical spacelike connection

  1. Aug 3, 2014 #1

    Jonathan Scott

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    One theory I've heard and which I find interesting is that entanglement between any pair of two-state systems could be explained deterministically by a spacelike connection which can only communicate something relative, like a phase difference, and which is essentially holding the ends instantaneously in step until one end or the other resolves the entangled state, breaking the connection. Of course the time sequence of the resolution at either end can be ambiguous, but the relative state at the point of resolution is unaffected by that.

    However, it's not clear to me what would be connected to what. In a trivial case of fermion wave functions, the two wave functions could be linked in some way. Photons (as in the Aspect experiments) are not in themselves two-state systems, but it is rather their polarization, but I guess that can be modelled as linked pairs of fermions as well. There are other experiments which involve two states of phases used in interference and so on.

    Is there known to be some possibility of a consistent model using spacelike connections which could explain entanglement, or is there any known experiment or theory which rules this out?
  2. jcsd
  3. Aug 3, 2014 #2
    Some possibility? I guess so, for instance if instead of considering spacelike separated correlated observations of spin or polarization as properties of separated particles you view them as purely geometrical properties then entanglement follows trivially.
  4. Aug 3, 2014 #3


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    Heard where? Sounds interesting, but a pointer would be even more interesting.
  5. Aug 6, 2014 #4

    Jonathan Scott

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    I originally came across it as one of the general categories of "explanation" mentioned at an "extension" lecture about entanglement and Aspect's experiments at an Open University summer school around 1990, but I've been assuming it is an obvious general approach to entanglement, to simply assume that there's something "really" connecting the entangled systems but that it can only convey something relative, such as a rotational phase.

    It didn't seem very plausible to me at the time (as I hadn't really fully accepted the inescapable nature of the Bell inequalities), but later after I'd looked at Cramer's Transactional Interpretation and got worried about a hole in it (involving timelike separations where the first event determines the test performed at the second event) I went back to look at it myself to see if the physical spacelike connection idea could make sense. I thought so at that time, but that was before I was aware of the wide variety of types of entanglement.

    I'm just revisiting the idea and I don't have any references myself, which is why I'm asking if anyone knows of any further attempts to investigate a physical connection of this type and how it might work in a way which would cover the different types of entanglement (for example through communicating a spin axis).

    I admit that when I tried to discuss this in more detail with the tutor on the course, he said that speculating on how QM "worked" was outside the scope of the course, and mostly we "just shut up and calculate".
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