Casimir Effects Near the Big Rip Singularity in Viscous Cosmology

TL;DR

This paper analyzes the behavior of the scalar expansion and cosmic fluid near the Big Rip singularity in viscous cosmology, considering the effects of Casimir energy contributions and their diminishing influence close to the singularity.

Contribution

It introduces a model incorporating Casimir effects into viscous cosmology and examines their impact near the Big Rip singularity, showing the Casimir influence fades at the singularity.

Findings

Casimir effects become negligible near the Big Rip

Scalar expansion behaves similarly with or without Casimir effects near the singularity

The scale factor and energy density exhibit the same singular behavior regardless of Casimir influence

Abstract

Analytical properties of the scalar expansion in the cosmic fluid are investigated, especially near the future singularity, when the fluid possesses a constant bulk viscosity \zeta. In addition, we assume that there is a Casimir-induced term in the fluid's energy-momentum tensor, in such a way that the Casimir contributions to the energy density and pressure are both proportional to 1/a^4, 'a' being the scale factor. A series expansion is worked out for the scalar expansion under the condition that the Casimir influence is small. Close to the Big Rip singularity the Casimir term has however to fade away and we obtain the same singular behavior for the scalar expansion, the scale factor, and the energy density, as in the Casimir-free viscous case.