Foundations of Physics

, Volume 24, Issue 12, pp 1589-1664

First online:

Interpretations of quantum mechanics, joint measurement of incompatible observables, and counterfactual definiteness

  • W. M. de MuynckAffiliated withDepartment of Theoretical Physics, Eindhoven University of Technology
  • , W. De BaereAffiliated withResearch associate N.F.W.O.Laboratory for Theoretical Physics, State University of Ghent
  • , H. MartensAffiliated withDepartment of Theoretical Physics, Eindhoven University of Technology

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The validity of the conclusion to the nonlocality of quantum mechanics, accepted widely today as the only reasonable solution to the EPR and Bell issues, is questioned and criticized. Arguments are presented which remove the compelling character of this conclusion and make clear that it is not the most obvious solution. Alternative solutions are developed which are free of the contradictions related with the nonlocality conclusion. Firstly, the dependence on the adopted interpretation is shown, with the conclusion that the alleged nonlocality property of the quantum formalism may have been reached on the basis of an interpretation that is unnecessarily restrictive. Secondly, by extending the conventional quantum formalism along the lines of Ludwig and Davies it is shown that the Bell problem may be related to complementarity rather than to nonlocality. Finally, the dependence on counterfactual reasoning is critically examined. It appears that locality on the quantum level may still be retained provided one accepts a newly proposed principle of nonreproducibility at the individual quantum level as an alternative of quantum nonlocality. It is concluded that the locality principle can retain its general validity, in full conformity with all experimental data.