Violation of Bell Inequalities: Mapping the Conceptual Implications

TL;DR

This paper explores the conceptual implications of Bell inequality violations, emphasizing that these do not definitively determine the nature of reality but constrain underlying theories and highlight issues like contextuality and assumptions.

Contribution

It provides a comprehensive map of the conceptual landscape surrounding Bell inequalities, clarifying misconceptions and emphasizing the nuanced implications for quantum foundations.

Findings

Bell violations constrain but do not rule out local realistic theories

Implications often overstated due to imprecise language and assumptions

Contextuality and measurement issues are central to understanding violations

Abstract

This short article concentrates on the conceptual aspects of the violation of Bell inequalities, and acts as a map to the 265 cited references. The article outlines (a) relevant characteristics of quantum mechanics, such as statistical balance and entanglement, (b) the thinking that led to the derivation of the original Bell inequality, and (c) the range of claimed implications, including realism, locality and others which attract less attention. The main conclusion is that violation of Bell inequalities appears to have some implications for the nature of physical reality, but that none of these are definite. The violations constrain possible prequantum (underlying) theories, but do not rule out the possibility that such theories might reconcile at least one understanding of locality and realism to quantum mechanical predictions. Violation might reflect, at least partly, failure to acknowledge the contextuality of quantum mechanics, or that data from different probability spaces have been inappropriately combined. Many claims that there are definite implications reflect one or more of (i) imprecise non-mathematical language, (ii) assumptions inappropriate in quantum mechanics, (iii) inadequate treatment of measurement statistics and (iv) underlying philosophical assumptions.