Real World Interpretations of Quantum Theory

TL;DR

This paper introduces 'real world interpretations' of quantum theory, proposing a mathematical framework with preferred factorizations and measurements to describe possible worlds in closed quantum systems, avoiding ambiguous concepts like quasiclassicality.

Contribution

It presents a novel class of interpretations that mathematically characterize possible worlds in quantum systems without relying on traditional ambiguous concepts.

Findings

Defines a new interpretation framework with preferred factorizations and measurements.

Mathematically characterizes possible worlds as evolving quantum states.

Suggests a natural probability distribution for selecting the realized world.

Abstract

I propose a new class of interpretations, {\it real world interpretations}, of the quantum theory of closed systems. These interpretations postulate a preferred factorization of Hilbert space and preferred projective measurements on one factor. They give a mathematical characterisation of the different possible worlds arising in an evolving closed quantum system, in which each possible world corresponds to a (generally mixed) evolving quantum state. In a realistic model, the states corresponding to different worlds should be expected to tend towards orthogonality as different possible quasiclassical structures emerge or as measurement-like interactions produce different classical outcomes. However, as the worlds have a precise mathematical definition, real world interpretations need no definition of quasiclassicality, measurement, or other concepts whose imprecision is problematic in other interpretational approaches. It is natural to postulate that precisely one world is chosen randomly, using the natural probability distribution, as the world realised in Nature, and that this world's mathematical characterisation is a complete description of reality.