Quantum Histories and Quantum Gravity

TL;DR

This paper reviews the histories approach to quantum mechanics and explores its implications for quantum gravity, emphasizing the importance of classical history approximation for recovering classical physics and constraining quantum gravity theories.

Contribution

It applies the histories framework to quantum gravity, highlighting the necessity of classical history approximation and its impact on theory formulation and classical correspondence.

Findings

Quantum histories must approximate classical histories for classical regime recovery.

Constraints on quantum gravity kinematics to preserve quantum/classical correspondence.

Implications for Lorentz symmetry and emergent geometry in quantum gravity.

Abstract

This paper reviews the histories approach to quantum mechanics. This discussion is then applied to theories of quantum gravity. It is argued that some of the quantum histories must approximate (in a suitable sense) to classical histories, if the correct classical regime is to be recovered. This observation has significance for the formulation of new theories (such as quantum gravity theories) as it puts a constraint on the kinematics, if the quantum/classical correspondence principle is to be preserved. Consequences for quantum gravity, particularly for Lorentz symmetry and the idea of "emergent geometry", are discussed.