Quantum empty Bianchi I spacetime with internal time

TL;DR

This paper investigates the role of internal time in quantum Bianchi I cosmology, revealing two classes of time parameters that either lead to or prevent singularities, and suggesting a potential resolution to the clock problem.

Contribution

It classifies internal time parameters in quantum Bianchi I cosmology and shows how different choices affect singularity avoidance and physical outcomes.

Findings

Fast-gauge time leads to singularities.

Slow-gauge time prevents singularities.

Existence of an asymptotic regime independent of clock choice.

Abstract

We discuss the question of time in a Bianchi I quantum cosmology in the framework of singularity avoidance. We show that time parameters fall into two distinct classes, that are such that the time development of the wave function either always leads to the appearance of a singularity (fast-gauge time) or that always prevents it from occurring (slow-gauge time). Furthermore, we find that, in the latter case, there exists an asymptotic regime, independent of the clock choice. This may point to a possible solution of the clock issue in quantum cosmology if there exists a suitable class of clocks all yielding identical relevant physical consequences.