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Bell theorem without hypotheses?

  1. May 8, 2015 #1
    i found the following proof of Bell's theorem :

    we measure spin in 3 different directions a b c we can note the counting of events

    N2. + + -
    N3. + - +
    N4. + - -
    N5. - + +
    N6. - + -
    N7. - - +

    We have N3+n4<=n7+n3+n4+n2

    With n3+n4=p(+a,-b)

    It is violated by quantum mechanics but i don't see where the hypothesis of locality and reality comes into play.
  2. jcsd
  3. May 8, 2015 #2


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    Science Advisor
    Gold Member

    The answer is that you can replicate the results with a classical system if either non-locality or non-realism are allowed. Surely, you could imagine non-local mechanisms that would allow 2 particles to mimic each other in just the right amount to give quantum results.

    Harder to picture non-realism. But essentially you are assuming this when you have N1=a+, b+, c+ because you only ever measure 2 of these at a time at most.
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