Quantum nonlocality: no, yes, how and why

TL;DR

This paper explores the nature of quantum nonlocality, arguing that while statistical violations of Bell's inequalities can be explained locally, the nonlocality observed in detection outcomes arises from contextual factors and is consistent with relativity.

Contribution

It introduces a simple model with contextual instructions that explains how nonlocality in detection outcomes arises, resolving the hard problem of quantum nonlocality.

Findings

Statistical violation of Bell's inequalities can be explained without nonlocality.

Nonlocality in detection outcomes exists but is unobservable directly.

Nonlocality is compatible with relativistic covariance.

Abstract

The problem of the existence of nonlocal effects in Quantum Mechanics is discussed. The problem is divided in two: the first ('soft') one is to explain the violation of Bell's inequalities as a statistical magnitude. This can be achieved by a simple model within non-Boolean Locality and Realism. This result shows that quantum non-Locality as a consequence of the statistical violation of Bell's inequalities is inexistent. The second ('hard') problem is to explain the violation as it is calculated from series of detection outcomes. L.Sica has demonstrated that, in order to violate Bell's inequalities, the series recorded at (say) Bob when the setting at station Alice is alfa, can be different from the series that would have been recorded at Bob if that setting had been alfa'instead. Therefore, non-Locality in the series of detection outcomes does exist. It cannot be experimentally verified because of its counterfactual nature, but is observed in computer simulations. An appropriate computer code is based on the simple model mentioned plus a contextual instruction. It explains 'how' (Sica's) non-Locality arises, and solves the hard problem. 'Why' the contextual instruction exists is explained by Hellwig and Kraus' postulate of covariant quantum state collapse. In consequence, (Sica's) non-Locality is not in contradiction with Relativity but, quite the opposite, it is implied by Relativistic covariance.