Gravitational instanton, inflation and cosmological constant

TL;DR

This paper explores how quantum fluctuations around gravitational instantons induce vacuum energy changes that drive early universe inflation and evolve into the observed cosmological constant, linking quantum gravity effects to cosmology.

Contribution

It proposes a mechanism where quantum black hole nucleation from gravitational instantons explains inflation and the cosmological constant evolution.

Findings

Vacuum energy gain from quantum fluctuations leads to inflation.

Reheating is caused by Hawking radiation of quantum black holes.

The model aligns with current cosmological observations.

Abstract

Quantum fluctuation of unstable modes about gravitational instantons causes the instability of flat space at finite temperature, leading to the spontaneous process of nucleating quantum black holes. The density of vacuum energy-gain in such process gives the cosmological term in the Einstein equation. This naturally results in the inflationary phase of Early Universe. While the reheating phase is attributed to the Hawking radiation of these quantum black holes. In the Standard cosmology era, this cosmological term depends on the reheating temperature and asymptotically approaches to the cosmological constant in matter domination phase, consistently with current observations.