Hints of (trans-Planckian) asymptotic freedom in semiclassical cosmology

TL;DR

This paper uses semiclassical methods in quantum cosmology to show that quantum gravitational effects diminish at early times, supporting the idea of asymptotic safety in quantum gravity.

Contribution

It demonstrates that quantum gravitational fluctuations become negligible near the Planck scale in a de Sitter universe, providing evidence for asymptotic safety.

Findings

Quantum gravitational effects are negligible at early times.

Scalar field states approach plane-waves asymptotically.

Modes originate from the minimum energy vacuum.

Abstract

We employ the semiclassical approximation to the Wheeler-DeWitt equation in the spatially flat de Sitter Universe to investigate the dynamics of a minimally coupled scalar field near the Planck scale. We find that, contrary to naive intuition, the effects of quantum gravitational fluctuations become negligible and the scalar field states asymptotically approach plane-waves at very early times. These states can then be used as initial conditions for the quantum states of matter to show that each mode essentially originated in the minimum energy vacuum. Although the full quantum dynamics cannot be solved exactly for the case at hand, our results can be considered as supporting the general idea of asymptotic safety in quantum gravity.