As far as I know violation of Bell's theorem is not a problem for De Broglie–Bohm theory because this theory is explicitly nonlocal; But since the violation of Leggett inequality is considered to falsify realism in quantum mechanics and if we define realism here in respect with quantum mechanical systems as: "physical systems possess complete sets of definite values for various parameters prior to, and independent of, measurement", and since Bohmian mechanics postulates an actual configuration that exists even when unobserved (having definite values at any given time), then is here an incompatibility between Bohmian mechanics and Leggett inequality?

It is causing confusion for me especially when more and more articles are calling for the abandonment of realism.

For example:

Independent experiments performed in 2007 by the Vienna team (Phys. Rev. Lett. 99 210406) and by researchers at the University of Geneva and the National University of Singapore (Phys. Rev. Lett. 99 210407) confirmed a violation of a Leggett inequality under more relaxed assumptions, thereby expanding the class of forbidden nonlocal realistic models. Two things are clear from these experiments. First, it is insufficient to give up completely the notion of locality. Second, one has to abandon at least the notion of naïve realism that particles have certain properties (in our case polarization) that are independent of any observation.

Aspelmeyer, M., & Zeilinger, A. (2008). A quantum renaissance. Physics World, 21(07), 22.

  • 2
    $\begingroup$ related questions by OP: physics.stackexchange.com/q/372350/84967, physics.stackexchange.com/q/372412/84967 $\endgroup$ – AccidentalFourierTransform Dec 4 '17 at 19:41
  • $\begingroup$ It will be like with all similar no-go theorems, that only a misconception about what they really prove can sound problematic for Bohm theory. (The reason is that, since Bohm's theory is empirically equivalent to Copenhagen, it also predicts correctly the violations of this inequality). Also, not ALL values are predetermined in Bohm's theory but only the positions (not momenta for example). $\endgroup$ – Luke Dec 7 '17 at 12:44

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