Quantum Locality?

TL;DR

This paper examines Griffiths' claims about quantum locality within his 'consistent quantum theory', analyzing the validity of proofs regarding nonlocal influences and clarifying misunderstandings about the framework's implications.

Contribution

It provides a detailed analysis of Griffiths' proof of locality, confirming its validity within his framework and clarifying misconceptions about nonlocal influences in quantum mechanics.

Findings

Griffiths' proof of locality is valid within his 'consistent quantum theory' framework.

The paper clarifies that certain proofs claiming nonlocality are flawed or based on incompatible assumptions.

Responses to Griffiths' objections show the robustness of the analyzed proof.

Abstract

Robert Griffiths has recently addressed, within the framework of a 'consistent quantum theory' that he has developed, the issue of whether, as is often claimed, quantum mechanics entails a need for faster-than-light transfers of information over long distances. He argues that the putative proofs of this property that involve hidden variables include in their premises some essentially classical-physics-type assumptions that are fundamentally incompatible with the precepts of quantum physics. One cannot logically prove properties of a system by establishing, instead, properties of a system modified by adding properties alien to the original system. Hence Griffiths' rejection of hidden-variable-based proofs is logically warranted. Griffiths mentions the existence of a certain alternative proof that does not involve hidden variables, and that uses only macroscopically described observable properties. He notes that he had examined in his book proofs of this general kind, and concluded that they provide no evidence for nonlocal influences. But he did not examine the particular proof that he cites. An examination of that particular proof by the method specified by his 'consistent quantum theory' shows that the cited proof is valid within that restrictive version of quantum theory. An added section responds to Griffiths' reply, which cites general possibilities of ambiguities that make what is to be proved ill-defined, and hence render the pertinent 'consistent framework' ill defined. But the vagaries that he cites do not upset the proof in question, which, both by its physical formulation and by explicit identification, specify the framework to be used. Griffiths confirms the validity of the proof insofar as that framework is used. The section also shows, in response to Griffiths' challenge, why a putative proof of locality that he has described is flawed.