Effective Inhomogeneous Cosmologies and Emerging Scalar Fields

TL;DR

This paper explores how inhomogeneities in the universe can be modeled as an effective scalar field, leading to new insights into cosmic evolution scenarios including inflation and dark energy.

Contribution

It demonstrates a correspondence between backreaction effects in inhomogeneous cosmologies and an effective scalar field, providing new models for cosmic evolution.

Findings

Backreaction terms can be interpreted as a scalar field ('morphon').

Different evolution scenarios, including inflation, emerge from inhomogeneity models.

Closure conditions lead to novel cosmological equations and interpretations.

Abstract

In this contribution we summarize two recent applications of a correspondence between backreaction terms in averaged inhomogeneous cosmologies and an effective scalar field (the `morphon'). Backreaction terms that add to the standard sources of Friedmannian kinematical laws and that emerge from geometrical curvature invariants built from inhomogeneities, can be interpreted in terms of a minimally coupled scalar field in the case of a dust matter source. We consider closure conditions of the averaged equations that lead to different evolution scenarii: a) the standard Chaplygin equation of state imposed as an effective relation between kinematical fluctuations and intrinsic curvature of space sections, and b) an inflationary scenario that emerges out of inhomogeneities of the Einstein vacuum, where averaged curvature inhomogeneities model the potential of an effective classical inflaton.