Classical limit of quantum gravity in an accelerating universe

TL;DR

This paper derives a classical limit of quantum gravity incorporating an inverse Riemann curvature term, relevant for accelerating universes, and explores its implications for black holes and string theory.

Contribution

It introduces a one-parameter deformation of Einstein-Hilbert gravity as a classical limit of quantum gravity compatible with acceleration.

Findings

Deformation includes an inverse Riemann curvature term.

Sectional curvature bounds prevent static black holes.

String theory remains unaffected by this deformation.

Abstract

A one-parameter deformation of Einstein?Hilbert gravity with an inverse Riemann curvature term is derived as the classical limit of quantum gravity compatible with an accelerating universe. This result is based on the investigation of semi-classical theories with sectional curvature bounds which are shown not to admit static spherically symmetric black holes if otherwise of phenomenological interest. We discuss the impact on the canonical quantization of gravity, and observe that worldsheet string theory is not affected.