Nonlocality in Bell's theorem, in Bohm's theory, and in Many Interacting Worlds theorising

TL;DR

This paper explores different notions of locality in quantum theories, focusing on Bell's theorem, Bohmian mechanics, and Many Interacting Worlds, and reports progress in modeling wavefunctions with nodes.

Contribution

It clarifies the concept of locality in quantum theories and advances the modeling of wavefunctions with nodes in the Many Interacting Worlds approach.

Findings

Progress in modeling wavefunctions with nodes

Clarification of locality concepts in quantum theories

Advancement in simulating Many Interacting Worlds

Abstract

'Locality' is a fraught word, even within the restricted context of Bell's theorem. As one of us has argued elsewhere, that is partly because Bell himself used the word with different meanings at different stages in his career. The original, weaker, meaning for locality was in his 1964 theorem: that the choice of setting by one party could never affect the outcome of a measurement performed by a distant second party. The epitome of a quantum theory violating this weak notion of locality (and hence exhibiting a strong form of nonlocality) is Bohmian mechanics. Recently, a new approach to quantum mechanics, inspired by Bohmian mechanics, has been proposed: Many Interacting Worlds. While it is conceptually clear how the interaction between worlds can enable this strong nonlocality, technical problems in the theory have thus far prevented a proof by simulation. Here we report significant progress in tackling one of the most basic difficulties that needs to be overcome: correctly modelling wavefunctions with nodes.