A short note on conflicting definitions of locality

TL;DR

This paper clarifies the different definitions of locality in physics, highlighting the overlap and differences, and argues against a specific interpretation related to Bell inequalities using a classical card example.

Contribution

It distinguishes three common non-equivalent definitions of locality and refutes a fourth, Bell-based definition as untenable through a classical example.

Findings

Most physicists associate non-locality with violations of one of three conditions.

A minority uses Bell inequality hypotheses as 'locality', which the paper challenges.

A classical card example demonstrates the untenability of the Bell-based definition.

Abstract

There are various non-equivalent definitions of locality. Three of them, impossibility of instantaneous communication, impossibility of action-at-a-distance, and impossibility of faster-than-light travel, while not fully implying each other, have a large overlap. When the term non-locality is used, most physicists think that one of these three conditions is being violated. There is a minority of physicists, however, who uses "locality" with a fourth meaning, the satisfaction of the hypotheses underlying Bell inequality. This definition devoids Bell's theorem of its profoundness, reducing it to a mere tautology. It is demonstrated here, through a classical example using a deck of cards, that this latter definition of "locality" is untenable.