# More on the regularized big bang singularity

## TL;DR

This paper explores a regularization of the big bang singularity by introducing a degenerate metric and a length scale, resulting in a nonsingular bounce that is compared with loop quantum and string cosmology bounces.

## Contribution

It provides a detailed calculation of the dynamics of a regularized big bang bounce using a degenerate metric and compares it with other quantum cosmology models.

## Key findings

- The regularized bounce avoids singularity with maximum curvature and density proportional to 1/b.
- The bounce features a contracting phase before and an expanding phase after the bounce.
- Maximum curvature and density are finite and depend on the length scale b.

## Abstract

The big bang singularity of the expanding-universe Friedmann solution of the Einstein gravitational field equation can be regularized by the introduction of a degenerate metric and a nonzero length scale $b$. The result is a nonsingular bounce of the cosmic scale factor with a contracting prebounce phase and an expanding postbounce phase. The corresponding maximum values of the curvature and the energy density occur at the moment of the bounce and are proportional to powers of $1/b$. This article presents a detailed calculation of the dynamics of such a nonsingular bounce. In addition, a comparison is made between this nonsingular bounce and the bounces of loop quantum cosmology and string cosmology.