Emergence of classical theories from quantum mechanics

TL;DR

This paper explores how classical theories can emerge from quantum mechanics by addressing key interpretational issues, proposing new assumptions and limits that reconcile quantum behavior with classical properties.

Contribution

It identifies tacit assumptions hindering the derivation of classical theories from quantum mechanics and proposes modifications to overcome these, including objective properties and fuzzy trajectories.

Findings

Classical properties can emerge from quantum mechanics via high entropy limits.

Objective properties defined by preparation resolve interpretational issues.

A new interpretation of quantum measurement is proposed to eliminate disturbance.

Abstract

Three problems stand in the way of deriving classical theories from quantum mechanics: those of realist interpretation, of classical properties and of quantum measurement. Recently, we have identified some tacit assumptions that lie at the roots of these problems. Thus, a realist interpretation is hindered by the assumption that the only properties of quantum systems are values of observables. If one simply postulates the properties to be objective that are uniquely defined by preparation then all difficulties disappear. As for classical properties, the wrong assumption is that there are arbitrarily sharp classical trajectories. It turns out that fuzzy classical trajectories can be obtained from quantum mechanics by taking the limit of high entropy. Finally, standard quantum mechanics implies that any registration on a quantum system is disturbed by all quantum systems of the same kind existing somewhere in the universe. If one works out systematically how quantum mechanics must be corrected so that there is no such disturbance, one finds a new interpretation of von Neumann's "first kind of dynamics", and so a new way to a solution of the quantum measurement problem. The present paper gives a very short review of this work.