On average properties of inhomogeneous cosmologies

TL;DR

This paper reviews recent advances in understanding inhomogeneous cosmologies by exploring effective descriptions of structural evolution, including Newtonian and relativistic approaches, and suggests future research directions.

Contribution

It provides a systematic re-evaluation of inhomogeneous cosmological models and discusses effective averaging methods in Newtonian and relativistic frameworks.

Findings

Insights into spatial averaging in Newtonian cosmology

Expansion laws in general relativity with covariant fluids

Future research directions in inhomogeneous cosmologies

Abstract

The present talk summarizes the recently progressed state of a systematic re-evaluation of cosmological models that respect the presence of inhomogeneities. Emphasis is given to identifying the basic steps towards an effective (i.e. spatially averaged) description of structural evolution, also unfolding the various facets of a `smoothed--out' cosmology. We shall highlight some results obtained within Newtonian cosmology, discuss expansion laws in general relativity within a covariant fluid approach, and put forward some promising directions of future research.