Further Exact Cosmological Solutions to Higher-Order Gravity Theories

TL;DR

This paper finds exact anisotropic cosmological solutions in higher-order gravity theories, showing deviations from general relativity can eliminate Mixmaster oscillations near singularities, with implications for early universe models.

Contribution

It introduces new exact vacuum solutions of modified Kasner type in fourth-order gravity theories, extending understanding of early universe anisotropies beyond general relativity.

Findings

Mixmaster oscillations are suppressed in these solutions.

New anisotropic vacuum solutions are derived for fourth-order gravity.

Deviations from general relativity affect approach to singularity.

Abstract

We investigate the effect of deviations from general relativity on approach to the initial singularity by finding exact cosmological solutions to a wide class of fourth-order gravity theories. We present new anisotropic vacuum solutions of modified Kasner type and demonstrate the extent to which they are valid in the presence of non-comoving perfect-fluid matter fields. The infinite series of Mixmaster oscillations seen in general relativity will not occur in these solutions, except in unphysical cases.