Identical quantum particles as distinguishable objects

TL;DR

This paper challenges the standard view of indistinguishable quantum particles, proposing an alternative conception where quantum particles are emergent and distinguishable like classical particles, addressing conceptual issues in quantum theory.

Contribution

It introduces a non-factorist approach to quantum particles, arguing they are emergent and distinguishable, aligning quantum and classical particle concepts.

Findings

Quantum particles are not fundamental but emergent.

Distinguishability of particles applies in applicable situations.

Addresses conceptual problems with factorism and indistinguishability.

Abstract

According to classical physics particles are basic building blocks of the world. Classical particles are distinguishable objects, individuated by physical characteristics. By contrast, in quantum mechanics the standard view is that particles of the same kind ("identical particles") are in all circumstances indistinguishable from each other. This indistinguishability doctrine is motivated by the (anti)symmetrization postulates together with the assumption (``factorism'') that each single particle is represented in exactly one factor space in the tensor product Hilbert space of a many-particles system. Although the factorist assumption is standard in the literature, it is conceptually problematic. Particle indistinguishability is incompatible with the everyday meaning of ``particle'', and also with how this term is used both in classical physics and in the experimental practice of physics. The standard view requires quantum particles of the same kind to remain indistinguishable even in the classical limit, so that a transition to the classical picture of the world seems impossible. Earlier we have proposed an alternative conception of quantum particles that does not rely on factorism and that avoids these and other problems. We further explain and develop this proposal here. In our view, particles in quantum theory are not fundamental but \emph{emergent}. However, in those situations where the particle concept is applicable, quantum particles---identical or not---are distinguishable in the same way as classical particles.