Viscous cosmologies in scalar-tensor theories for Kasner type metrics

TL;DR

This paper explores viscous cosmological models within scalar-tensor theories, demonstrating that such models can satisfy thermodynamic laws and energy conditions unlike in Einstein's gravity.

Contribution

It introduces scalar-tensor theories as a framework to model viscous Kasner-type universes that comply with thermodynamics and energy conditions.

Findings

Viscous Kasner metrics can satisfy the second law of thermodynamics.

Scalar-tensor theories enable anisotropic models to meet energy conditions.

The approach broadens the scope of viable cosmological models.

Abstract

In a viscous Bianchi type I metric of the Kasner form, it is well known that it is not possible to describe an anisotropic physical model of the universe, which satisfies the second law of thermodynamics and the dominant energy condition (DEC) in Einstein's theory of gravity. We examine this problem in scalar-tensor theories of gravity. In this theory we show that it is possible to describe the growth of entropy, keeping the thermodynamics and the dominant energy condition.