Towards a Nonsingular Universe

TL;DR

This paper proposes an effective gravitational action that ensures all homogeneous and isotropic solutions are nonsingular, eliminating big bang and big crunch singularities, and potentially resolving black hole singularities.

Contribution

It introduces a novel effective action for gravity that guarantees nonsingular solutions, extending general relativity at high curvatures.

Findings

All homogeneous and isotropic solutions are nonsingular.

Black hole interiors are free of singularities.

Anisotropies decrease at high curvatures.

Abstract

A unified theory of all forces should be nonsingular. In such a unified theory, Einstein's general relativity will be a very low curvature effective theory. At larger curvatures, new terms will become important. The question then arises as to whether it is possible to construct an effective action for gravity which leads to a nonsingular theory. In this work, we construct an effective action for gravity in which all homogenerous and isotropic solutions are nonsingular. In particular, there is neither a big bang nor a big crunch. Preliminary work indicates that our construction provides a theory in which anisotropies decrease at large curvatures, and in which the inside of a black hole is singularity free.