Effective inhomogeneous inflation: curvature inhomogeneities of the Einstein vacuum

TL;DR

This paper demonstrates that inhomogeneous vacuum geometries can generate an effective scalar field that drives inflation, leading to a flat, homogeneous universe without external matter sources.

Contribution

It introduces a novel mechanism where curvature inhomogeneities in vacuum spacetime produce an inflaton-like scalar field, enabling inflation without matter or energy sources.

Findings

Inhomogeneous vacuum models can produce an effective inflaton field.

The scalar field drives inflation from negative curvature.

The mechanism naturally leads to a flat, homogeneous universe.

Abstract

We consider spatially averaged inhomogeneous universe models and argue that, already in the absence of sources, an effective scalar field arises through foliating and spatially averaging inhomogeneous geometrical curvature invariants of the Einstein vacuum. This scalar field (the `morphon') acts as an inflaton, if we prescribe a potential of some generic form. We show that, for any initially negative average spatial curvature, the morphon is driven through an inflationary phase and leads - on average - to a spatially flat, homogeneous and isotropic universe model, providing initial conditions for pre-heating and, by the same mechanism, a possibly natural self-exit.