Horava-Lifshitz gravity, absolute time, and objective particles in curved space

TL;DR

This paper explores a version of quantum gravity that introduces absolute time, enabling a clear definition of particles in curved space and providing new insights into observer-dependent phenomena like the Unruh effect.

Contribution

It proposes a framework where absolute time in Horava-Lifshitz gravity allows for an objective particle concept in curved spacetime, contrasting with traditional observer-dependent notions.

Findings

Objective particles can be consistently defined in curved space.

The Unruh effect is interpreted as an interaction effect with objective particles.

The theory maintains compatibility with general relativity at large scales.

Abstract

Recently, Horava formulated a renormalizable theory of quantum gravity that reduces to general relativity at large distances but violates Lorentz invariance at small distances. The absolute time involved in this theory allows to define an objective notion of particles associated with quantization of fields in classical gravitational backgrounds. The Unruh effect and other observer-dependent notions of particles in curved space are interpreted as effects caused by interaction between the objective vacuum and the measuring apparatus made up of objective particles.