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Nonlocality Versus Modified Realism

Foundations of Physics volume 50, pages 1–26 (2020)Cite this article

Abstract

A large number of physicists now admit that quantum mechanics is a non-local theory. The EPR argument and the many experiments (including recent “loop-hole free” tests) showing the violation of Bell’s inequalities seem to have confirmed convincingly that quantum mechanics cannot be local. Nevertheless, this conclusion can only be drawn inside a standard realist framework assuming an ontic interpretation of the wave function and viewing the collapse of the wave function as a real change of the physical state of the system. We show that this standpoint is not mandatory and that if the collapse is not considered an actual physical change it is possible to recover locality.

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Notes

  1. See for example [27] for a typical exposition of this quest.

  2. A detailed presentation of Convivial Solipsism and its consequences is given in [23,24,25].

  3. See https://www.youtube.com/watch?v=9CEr2GfGilw.

  4. Actually, things are more complex than that. There is a subtlety due to the decoherence mechanism and the choice of the preferred basis that we forget here. See [24] for a detailed account of this point.

  5. See for example Wallace [39] who claims having proved the Born rule in this context and Kent [40] who denies that it is the case.

  6. Actually the hanging-on mechanism is a little bit more complex if both decoherence and the relativity of states (see below) are taken into account, but this has no impact on what we want to say here. See [24] for a more detailed presentation.

  7. See [24] for a more detailed comparison between Convivial Solipsism and the relational interpretation and QBism and for a description of the issues that, from my point of view, these two latter interpretations face.

  8. Of course, we do not pretend being able to explain how awareness happens. This is probably one of the most difficult problems of the contemporary science. Neuroscientists are hardly beginning to understand some mechanisms showing how consciousness works and how different it is from what our own consciousness itself thinks it is working.

  9. See [25] for a more detailed discussion of this point.

  10. Actually, experiments showing the violation of Bell’s inequalities in such a situation have been carried on.

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Acknowledgements

I want to thank Chris Fuchs for many enlightening discussions about QBism and Lev Vaidman for exchanges allowing me to better understand his own presentation of Everett’s interpretation.

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Authors and Affiliations

  1. CMLA, ENS Paris Saclay, 61 Avenue du Président Wilson, 94235, Cachan, France

    Hervé Zwirn

  2. IHPST CNRS, ENS Ulm, University Paris 1, 13 Rue du Four, 75006, Paris, France

    Hervé Zwirn

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Correspondence to Hervé Zwirn.

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Zwirn, H. Nonlocality Versus Modified Realism. Found Phys 50, 1–26 (2020). https://doi.org/10.1007/s10701-019-00314-7

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Keywords

  • Non-locality
  • Collapse
  • Measurement problem
  • Consciousness
  • Everett’s interpretation
  • Convivial solipsism