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Quantum twins

  1. Apr 9, 2007 #1
    Tell me if the analogy holds:

    Twins are generated by black eye fathers and green eyed mothers

    Let it be the "green eye" or the "black eye" our observable variable.
    Only identical twins are chosen.

    The twins A and B are sealed, each one, in a closed box,
    we have to predict the color of the eyes of twin B by opening the box
    of twin A: we don't know anything about the genetic laws and about the
    color of the eyes of the parents.

    If we only open a stream of A boxes the statistic of the outcome is a
    random distribution of 50% of green eyes and 50% of black eyes.

    When we open the box A we know that B will have the same color as A.

    Of course the correlation is preexistent at our opening the twin box
    A , nevertheless the prediction is only possible after we open the twin A
    box not before.

    This is a clear case of hidden variable: the genetic and the parent

    please comment.

    best regards

    beda pietanza
  2. jcsd
  3. Apr 9, 2007 #2


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    Science Advisor

    What makes quantum physics different is that the correlations cannot be explained by "local hidden variables", ie the idea that the correlations can be explained by imagining that the source of the two particles creates them in correlated states which guarantee they'll give the same results when you make the same measurements, as in your example. The statistics in quantum physics violate "Bell inequalities", and it's been proven by Bell's Theorem that this is incompatible with local hidden variables; your example would not violate any of these inequalities. You might want to check out the thread non-locality, where in post #10 I gave this example:
    Last edited: Apr 9, 2007

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