Quantum Particle Production at Sudden Singularities

TL;DR

This paper examines quantum particle production near a sudden singularity in a Friedmann universe, finding it insufficient to alter or avoid the singularity, thus suggesting limited observable effects.

Contribution

It provides an exact calculation of particle production at a sudden singularity and demonstrates its negligible impact on the singularity's nature.

Findings

Quantum particle production density is much smaller than background density.

Particle production does not prevent or modify the sudden singularity.

Residual anisotropies are unlikely to change the results.

Abstract

We investigate the effects of quantum particle production on a classical sudden singularity occurring at fine time in a Friedmann universe. We use an exact solution to describe an initially radiation-dominated universe that evolves into a sudden singularity at finite time. We calculate the density of created particles exactly and find that it is generally much smaller than the classical background density and pressure which produce the sudden singularity. We conclude that, in the example studied, the quantum particle production does not lead to the avoidance or modification to the sudden future singularity. We argue that the effects of small residual anisotropies in the expansion will not change these results and show how they can be related to studies of classical particle production using a bulk viscosity. We conclude that we do not expect to see significant observable effects from local sudden singularities on our past light cone.