The case for cosmic acceleration: Inhomogeneity versus cosmological constant

TL;DR

This paper proposes an alternative explanation for cosmic acceleration based on inhomogeneous spacetime models, suggesting that matter inhomogeneity, rather than a cosmological constant, accounts for observed supernova data.

Contribution

It introduces a spherically symmetric inhomogeneous model with matter inhomogeneity causing apparent acceleration, challenging the standard cosmological constant explanation.

Findings

Inhomogeneity can mimic cosmic acceleration effects.

Model maintains isotropy consistent with CBR observations.

Provides an alternative to dark energy explanation.

Abstract

In this work, I develop an alternative explanation for the acceleration of the cosmic expansion, which seems to be a result of recent high redshift Supernova data. In the current interpretation, this cosmic acceleration is explained by including a positive cosmological constant term (or vacuum energy), in the standard Friedmann models. Instead, I will consider a Locally Rotationally Symmetric (LRS) and spherically symmetric (SS), but inhomogeneous spacetime, with a barotropic perfect fluid equation of state for the cosmic matter. The congruence of matter has acceleration, shear and expansion. Within this framework the kinematical acceleration of the cosmic fluid or, equivalently, the inhomogeneity of matter, is just the responsible of the SNe Ia measured cosmic acceleration. Although in our model the Cosmological Principle is relaxed, it maintains almost isotropy about our worldline in agreement with CBR observations.