Spacetime expansion in the presence of a background velocity field

TL;DR

This paper proposes a modified spacetime metric with a velocity term that can explain cosmic expansion, inflation, and dark matter alternatives without breaking Lorentz symmetry, supported by null geodesic analysis.

Contribution

Introduces a new spacetime metric with a velocity-based term that accounts for universe expansion and black hole formation without dark matter or dark energy.

Findings

Velocity variations are too small to detect experimentally.

Models can explain early universe expansion and late-time acceleration.

Primordial black holes can form without dark matter.

Abstract

In this article, we introduce a new metric assuming an additional velocity-based term in a spacetime metric. Although the inclusion of this additional phrase can indicate that the Lorentz symmetry has broken, the results of null geodesics demonstrate that the amount of variation in the speed of light is considerably smaller than what can be observed. This article delves into the primary use of this additional phrase in the expansion development of Minkowski and de Sitter spacetimes. The findings indicate that multiple versions of the velocity function may explain the universe's initial explosion and expansion behavior even before the inflation epoch, the inflation itself, and the universe's positive acceleration in late time cosmology without dark matter or dark energy. These models can also rebuild primordial black holes in the early universe as an alternative to dark matter.