Stable Isotropic Cosmological Singularities in Quadratic Gravity

Abstract

We show that, in quadratic lagrangian theories of gravity, isotropic cosmological singularities are stable to the presence of small scalar, vector and tensor inhomogeneities. Unlike in general relativity, a particular exact isotropic solution is shown to be the stable attractor on approach to the initial cosmological singularity. This solution is also known to act as an attractor in Bianchi universes of types I, II and IX, and the results of this paper reinforce the hypothesis that small inhomogeneous and anisotropic perturbations of this attractor form part of the general cosmological solution to the field equations of quadratic gravity. Implications for the existence of a 'gravitational entropy' are also discussed.

18 pages, no figures

References in corpus (1)

• Lanczos potentials and a definition of gravitational entropy for perturbed FLRW space-times

Cited by in corpus (6)

• The Cosmology of Ricci-Tensor-Squared Gravity in the Palatini Variational Approach
• The Parameterised Post-Newtonian Limit of Fourth-Order Theories of Gravity
• Perihelion precession for modified Newtonian gravity
• Higher Powers in Gravitation
• The Stability of an Isotropic Cosmological Singularity in Higher-Order Gravity
• Quadratic superconducting cosmic strings revisited