One-loop quantum gravity repulsion in the early Universe

TL;DR

This paper uses perturbative quantum gravity to calculate one-loop corrections to early Universe cosmology, revealing quantum-induced repulsive effects that could influence the Universe's initial expansion.

Contribution

It demonstrates that quantum corrections from graviton vacuum polarization produce repulsive effects in early Universe models, akin to loop quantum cosmology.

Findings

Quantum corrections are UV cutoff free.

Quantum effects produce repulsive forces in early Universe.

Corrections are significant in the very early Universe.

Abstract

Perturbative quantum gravity formalism is applied to compute the lowest order corrections to the classical spatially flat cosmological FLRW solution (for the radiation). The presented approach is analogous to the approach applied to compute quantum corrections to the Coulomb potential in electrodynamics, or rather to the approach applied to compute quantum corrections to the Schwarzschild solution in gravity. In the framework of the standard perturbative quantum gravity, it is shown that the corrections to the classical deceleration, coming from the one-loop graviton vacuum polarization (self-energy), have (UV cutoff free) opposite to the classical repulsive properties which are not negligible in the very early Universe. The repulsive "quantum forces" resemble those known from loop quantum cosmology.