Full causal dissipative cosmologies with stiff matter

TL;DR

This paper derives a full causal solution for a viscous stiff fluid cosmology in flat FRW spacetime, analyzing its evolution from a singular state with detailed physical and geometric properties.

Contribution

It provides the first complete causal solution for a stiff viscous cosmology with a specific bulk viscosity dependence, including detailed dynamical and invariant analyses.

Findings

Universe starts from a singular state without inflation

Scale factor and invariants evolve with specific time dependencies

Viscous effects significantly influence cosmological dynamics

Abstract

The general solution of the gravitational field equations for a full causal bulk viscous stiff cosmological fluid, with bulk viscosity coefficient proportional to the energy density to the power 1/4, is obtained in the flat Friedmann-Robertson-Walker geometry. The solution describes a non-inflationary Universe, which starts its evolution from a singular state. The time variation of the scale factor, deceleration parameter, viscous pressure, viscous pressure-thermodynamic pressure ratio, comoving entropy and Ricci and Kretschmann invariants is considered in detail.