Macroscopic observables and Lorentz violation in discrete quantum gravity

TL;DR

This paper examines how discrete quantum gravity models may inherently violate Lorentz invariance when their microscopic histories fail to approximate continuum physics accurately in all frames.

Contribution

It analyzes the relationship between discrete quantum gravity structures and Lorentz violation, highlighting the implications of sum-over-histories formulations for symmetry preservation.

Findings

Lorentz violation arises if microscopic histories poorly approximate continuum physics in some frames.

Discrete structures in quantum gravity can lead to Lorentz symmetry breaking.

The sum-over-histories approach impacts the preservation of local Lorentz invariance.

Abstract

This article concerns the fate of local Lorentz invariance in quantum gravity, particularly for approaches in which a discrete structure replaces continuum spacetime. Some features of standard quantum mechanics, presented in a sum-over-histories formulation, are reviewed, and their consequences for such theories are discussed. It is argued that, if the individual histories of a theory give bad approximations to macroscopic continuum properties in some frames, then it is inevitable that the theory violates Lorentz symmetry.