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B Other terms for indeterministic hidden variables

  1. Jul 6, 2016 #1

    gva

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    If there were nonlocal hidden variables that are indeterministic and doesn't obey counterfactual definiteness. What terms should they be called. I think hidden variable should only be reserved for deterministic counterfactual definite.

    What then should we refer to indeterministic non-counterfactual definiteness. You may state contextuality? But contextuality is not hidden variables. I'm referring to actual processes in say the quantum vacuum that can produce stochastic randomness in the wave function. What term should we refer to it? Objective collapse? but it's not about collapse and not objective.

    Please suggest a term.
     
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  3. Jul 6, 2016 #2

    Nugatory

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    Staff: Mentor

    I am not aware of any such term being in general use, and expect that that is because the classification between deterministic and non-deterministic hidden variable theories is not interesting enough to require it.
     
  4. Jul 6, 2016 #3

    gva

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    There are official non-deterministic hidden variable theories? any references about this or examples?
     
  5. Jul 7, 2016 #4

    bhobba

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    Well Feynman's sum over history approach is really a hidden variable theory - but of a very novel type. The path is the hidden variable and most definitely is not deterministic - it takes all paths.

    That said, while novel, it's really not that interesting in discussions about hidden variables since such 'weird' things are not what attract people to such theories because they want a more common sense view of the world.

    Another example, and more interesting as an actual theory, is primary state diffusion:
    http://arxiv.org/pdf/quant-ph/9508021.pdf

    Its quite interesting because its not actually equivalent to QM - in that way it can bypass no go theorems like Bell and Kochen-Sprecker.

    We also have Nelson Stochastics
    http://philsci-archive.pitt.edu/8853/1/Nelson-revised.pdf:

    Thanks
    Bill
     
  6. Jul 7, 2016 #5

    gva

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    If there were really non-local hidden variables.. does it only affect system in an entanglement state? Or does it also affect everyday quantum dynamics in a decohered state?
     
  7. Jul 7, 2016 #6

    Nugatory

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    A hidden variable theory would use the hidden variables to predict the same results as quantum mechanics, so would apply everywhere that QM does (and perhaps even more broadly).

    A successful hidden variable theory would be to quantum mechanics as classical mechanics is to thermodynamics.
     
  8. Jul 7, 2016 #7

    gva

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    In quantum computing, the electron spin up and down can be used to encode 0 and 1. If there was hidden variable, can one encode more information in the quantum system. Or in other words, would there be changes in quantum computing concepts if there were (nonlocal) hidden variable?
     
  9. Jul 7, 2016 #8

    Nugatory

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    Staff: Mentor

    This is like asking whether if we discovered a new theory of aerodynamics, would there be changes in aircraft engineering concepts that allowed us to build planes that flew higher and faster. The question makes no sense unless and until we have a particular candidate theory in mind.

    However, any acceptable hidden variable theory must agree with QM everywhere that QM has been shown to work. As QM already does an excellent job at describing the behavior of electrons, there is little chance that a hidden variable theory that explains why QM works will change the way we manipulate electrons.

    I've already used the analogy with thermodynamics once, and it applies here as well. We were applying thermodynamics long before we discovered the hidden variable explanation for why it works so well. That discovery didn't force a rethinking of how we apply thermodynamics.
     
  10. Jul 7, 2016 #9

    bhobba

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    Of course not.

    Hidden variable theories (with a couple of exceptions such as Primary State Diffusion) are deliberately cooked up to be indistinguishable from standard QM. It is doubtful those few exceptions would allow that.

    Thanks
    Bill
     
  11. Jul 7, 2016 #10
    Any hidden variable theory implies counterfactual definiteness, at least if the theory is so detailed that it can be written as a computer program.

    Assume for the sake of argument that the theory is implemented as a computer simulation. We simulate a run with Alice's detector setting equal to A1, and get a result. Then we run the program again with setting equal to A2, keeping everything else about the program unchanged, including the values of any random variables from the first run. This will always be possible, and is equivalent to "counterfactual definiteness".
     
  12. Jul 7, 2016 #11

    gva

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    Counterfactual definiteness is very Newtonian.. and if this is related to hidden variable (which it is) and realism.. then those of us who prefer contextuality should avoid it all altogether. So let me now focus on non-realism or contextuality. What do you call that extra variable inside contextual QM where it can determine the born rule?
     
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