Do primordial Lithium abundances imply there's no Dark Energy?

TL;DR

This paper proposes that cosmic inhomogeneity, such as a large void, can explain both the universe's apparent acceleration and the Lithium problem without invoking dark energy, challenging standard cosmological assumptions.

Contribution

It introduces a void model that accounts for cosmic acceleration and Lithium abundance discrepancies by relaxing the assumption of large-scale homogeneity.

Findings

Inhomogeneous models can replicate observed acceleration without dark energy.

Lithium abundance discrepancies can be explained by cosmic inhomogeneity.

The model remains consistent with cosmic microwave background observations.

Abstract

Explaining the well established observation that the expansion rate of the universe is apparently accelerating is one of the defining scientific problems of our age. Within the standard model of cosmology, the repulsive 'dark energy' supposedly responsible has no explanation at a fundamental level, despite many varied attempts. A further important dilemma in the standard model is the Lithium problem, which is the substantial mismatch between the theoretical prediction for 7-Li from Big Bang Nucleosynthesis and the value that we observe today. This observation is one of the very few we have from along our past worldline as opposed to our past lightcone. By releasing the untested assumption that the universe is homogeneous on very large scales, both apparent acceleration and the Lithium problem can be easily accounted for as different aspects of cosmic inhomogeneity, without causing problems for other cosmological phenomena such as the cosmic microwave background. We illustrate this in the context of a void model.