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Intro to Bell's Theorem

  1. Aug 12, 2004 #1
    I have found a site that derives Bell's inequality
    The number of objects which have parameter A but not parameter B plus the number of objects which have parameter B but not parameter C is greater than or equal to the number of objects which have parameter A but not parameter C.

    And I follow this derivation alright, but I have seen examples where this inequality is violated when the objects we imply this inequality to things in the quantum world like the spin of an electron for orientations of different angles. Now, what I read is that these violations are not really violations due to the fact that Bell's theory is based on the assumptions that logic is valid and that hidden variables exist locally. What are hidden variables exactly? And what is the significance of Bell's Theorem?

    Note* I know this is similar to the post earlier on Bohmian mechanics but I wanted to take a step backwards for a moment before even beginning to look into Bohm's Implicate Order ideas.
  2. jcsd
  3. Aug 12, 2004 #2


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    A hidden variable theory is one that claims the weirdness of QM is due to neglecting some unknown factor(s), which cannot be observed at present, but which by their dynamics account for the quantum effects without breking with classical physics. Bell showed that for any such theory which also respects relativity, any local hidden variable theory, the inequality would be strict, but quantum mechanics predicts equality.
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