Lemaitre-Tolman-Bondi model and accelerating expansion

TL;DR

The paper explores how inhomogeneous LTB models can mimic accelerated cosmic expansion observed via supernova data without invoking dark energy, by considering spatial variations in matter density and Hubble rate.

Contribution

It demonstrates that inhomogeneous LTB models can explain supernova observations traditionally attributed to dark energy, challenging the standard homogeneous cosmology assumptions.

Findings

Inhomogeneous LTB models can fit supernova data without dark energy.

Spatial variations in Hubble rate can mimic acceleration effects.

Review of semi-realistic universe descriptions using LTB models.

Abstract

I discuss the spherically symmetric but inhomogeneous Lemaitre-Tolman- Bondi (LTB) metric, which provides an exact toy model for an inhomogeneous universe. Since we observe light rays from the past light cone, not the expansion of the universe, spatial variation in matter density and Hubble rate can have the same effect on redshift as acceleration in a perfectly homogeneous universe. As a consequence, a simple spatial variation in the Hubble rate can account for the distant supernova data in a dust universe without any dark energy. I also review various attempts towards a semirealistic description of the universe based on the LTB model.