Locality & Determinism beneath the quantum surface?

  1. It seems everyone think that Bell Inequalities rules out any hope of ever getting a local and deterministic account of reality.
    This need not be so...

    Gerard 't Hooft (Nobel Prize winner of 1999) has been working on a theory that may explain the quantum behaviour in a classical way.


    Layman link:
    http://sdsu-physics.org/physics180/physics180B/chapstuff/quantum_freewill.html

    Technical link:
    http://arxiv.org/PS_cache/quant-ph/pdf/0604/0604008v2.pdf
     
  2. jcsd
  3. JesseM

    JesseM 8,491
    Science Advisor

    Where does it say his model is a local one?

    Edit: this wikipedia article does say at the bottom that he is interested in finding a local model by exploiting the superdeterminism loophole (though I am not sure that your links actually concerns such a model), which I think is equivalent to the "no-conspiracy assumption" which is always mentioned in any rigorous proof of Bell's theorem (for example, see section D on p.6 of this proof). A violation of this condition is logically possible but would be physically bizarre, it would mean for example that if an experimenter chose on a whim each day whether to have cereal, pancakes or an omelet for breakfast, and on each day used this seemingly random choice to decide which detector setting to use for a particle which had been in flight for exactly a year, then one year earlier the laws of physics must have behaved as if they were "choosing" what hidden variables to assign to the particle based on what the experimenter would decide to have for breakfast one year later.
     
    Last edited: May 2, 2011
  4. JesseM

    JesseM 8,491
    Science Advisor

    You mean the very end part? They don't quote t'Hooft himself in that last section, just someone talking about his ideas, and the guy doesn't exactly say his hoped-for model would be fully local, but rather that this type of model "represents a kind of compromise" between two views that aren't explained very clearly (they describe one view as saying that quantum correlations are "real" while the deterministic view "rules them out", but I don't know exactly what either statement would mean at a more technical level).
     
  5. JesseM

    JesseM 8,491
    Science Advisor

    Incidentally, I see that Richard Gill, who is quoted making the comments about locality in the last section of the article, also has a paper here where he talks about t'Hooft and superdeterminism on p. 19-20:
    The first position he describes seems analogous to my example where the laws of physics seem to choose the properties to assign to a particle based on what an experimenter will decide to have for breakfast one year later, but I don't quite understand what he's talking about in that last paragraph, I guess it's basically that a loophole-free Bell test would turn out to be impossible for some reason.
     
    Last edited: May 2, 2011
  6. DrChinese

    DrChinese 5,737
    Science Advisor
    Gold Member

    You know, any ad hoc theory can explain things. Yet it will be completely useless as science.

    Just as Bell demonstrated that realism leads to testable requirements, a serious theory of super-determinism will do the same. In essence, this would require every particle to contain all information about all particles everywhere.

    Howsa 'bout something that actually explains or predicts something?
     
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