Quantum Mechanics in the Light of Quantum Cosmology

TL;DR

This paper proposes a quantum cosmology framework that explains the emergence of classical experience through decoherence and quasiclassical domains, linking initial conditions to the universe's classical appearance.

Contribution

It introduces a comprehensive quantum cosmology approach that describes the origin of classicality and measurement via decoherence and alternative histories of the universe.

Findings

Decoherence enables probabilities to be assigned to consistent histories.

A quasiclassical domain emerges as a set of decohering, highly correlated histories.

The initial conditions and particle actions determine the emergence of classical domains.

Abstract

We sketch a quantum mechanical framework for the universe as a whole. Within that framework we propose a program for describing the ultimate origin in quantum cosmology of the quasiclassical domain of familiar experience and for characterizing the process of measurement. Predictions in quantum mechanics are made from probabilities for sets of alternative histories. Probabilities can be assigned only to sets of histories that approximately decohere. Decoherence is defined and the mechanism of decoherence is reviewed. Decoherence requires a sufficiently coarse-grained description of alternative histories of the universe. A quasiclassical domain consists of a branching set of alternative decohering histories, described by a coarse graining that is maximally refined consistent with decoherence, with individual branches that exhibit a high level of classical correlation in time. A quasiclassical domain is emergent in the universe as a consequence of the initial condition and the action function of the elementary particles. It is an important question whether all the quasiclassical domains are roughly equivalent or whether there are various essentially inequivalent ones. A measurement is a correlation with variables in a quasiclassical domain. An observer (or information gathering and utilizing system) is a complex adaptive system that has evolved to exploit the relative predictability of a quasiclassical domain. We suggest that resolution of many of the problems of interpretation presented by quantum mechanics is to be accomplished, not by further scrutiny of the subject as it applies to reproducible laboratory situations, but rather by an examination of alternative histories of the universe, stemming from its initial condition, and a study of the problem of quasiclassical domains.