De Broglie-Bohm Pilot-Wave Theory: Many Worlds in Denial?

TL;DR

This paper defends the de Broglie-Bohm pilot-wave theory against claims it is equivalent to many-worlds, emphasizing its ontological basis and unique measurement theory, and argues that many-worlds is based on questionable classical measurement assumptions.

Contribution

The paper clarifies the ontological and measurement aspects of pilot-wave theory, countering claims that it is essentially a many-worlds interpretation.

Findings

Pilot-wave theory contains an ontological pilot wave and a subquantum measurement theory.

Many-worlds claims arise from misinterpretation of pilot-wave theory's terms.

Realistic models do not produce localized pilot waves following multiple macroscopic trajectories.

Abstract

We reply to claims (by Deutsch, Zeh, Brown and Wallace) that the pilot-wave theory of de Broglie and Bohm is really a many-worlds theory with a superfluous configuration appended to one of the worlds. Assuming that pilot-wave theory does contain an ontological pilot wave (a complex-valued field in configuration space), we show that such claims arise from not interpreting pilot-wave theory on its own terms. Specifically, the theory has its own ('subquantum') theory of measurement, and in general describes a 'nonequilibrium' state that violates the Born rule. Furthermore, in realistic models of the classical limit, one does not obtain localised pieces of an ontological pilot wave following alternative macroscopic trajectories: from a de Broglie-Bohm viewpoint, alternative trajectories are merely mathematical and not ontological. Thus, from the perspective of pilot-wave theory itself, many worlds are an illusion. It is further argued that, even leaving pilot-wave theory aside, the theory of many worlds is rooted in the intrinsically unlikely assumption that quantum measurements should be modelled on classical measurements, and is therefore unlikely to be true.