Quantum Ontology: Out of This World?

Abstract

Many commentators agree (based on the PBR theorem or other less-rigorous but still-compelling arguments) that the quantum mechanical wave function must represent some physically real thing/things/stuff. Existing proposals for the nature of this thing/things/stuff have tended to reflect the mathematically abstract character of the wave function: it has been suggested that the wave function represents, for example, a physical field of a mysterious and indeed rather incomprehensible character; or maybe a more comprehensibly-physical field that (incomprehensibly) lives not in ordinary physical space but instead in an abstract high-dimensional space; or maybe a non-local beable of a genuinely novel and ineffable sort; or maybe a kind of reified Law of Nature. None of these proposals is fully satisfying, physically and/or philosophically. The goal of the present paper is to advocate, by developing an analogy to two equivalent formulations of classical mechanics, for an under-appreciated alternative possibility—namely that the quantum wave function could represent some thing/things/stuff of a more mundane and more easily comprehensible character.