Towards Nonperturbative Renormalizability of Quantum Einstein Gravity

TL;DR

This paper discusses evidence that four-dimensional Quantum Einstein Gravity may be nonperturbatively renormalizable, potentially resolving key cosmological issues without requiring inflation, and establishing a fixed point for a consistent quantum gravity theory.

Contribution

It provides evidence for a non-Gaussian fixed point in Quantum Einstein Gravity supporting its nonperturbative renormalizability and explores its cosmological implications.

Findings

Existence of a suitable non-Gaussian fixed point for QEG.

QEG could solve horizon and flatness problems without inflation.

Supports the asymptotic safety scenario for quantum gravity.

Abstract

We summarize recent evidence supporting the conjecture that four-dimensional Quantum Einstein Gravity (QEG) is nonperturbatively renormalizable along the lines of Weinberg's asymptotic safety scenario. This would mean that QEG is mathematically consistent and predictive even at arbitrarily small length scales below the Planck length. For a truncated version of the exact flow equation of the effective average action we establish the existence of a non-Gaussian renormalization group fixed point which is suitable for the construction of a nonperturbative infinite cutoff-limit. The cosmological implications of this fixed point are discussed, and it is argued that QEG might solve the horizon and flatness problem of standard cosmology without an inflationary period.