More General Sudden Singularities

TL;DR

This paper introduces a broad class of sudden singularities in expanding Friedmann universes where pressure and acceleration diverge while the scale factor and density stay finite, applicable to general relativity and modified gravity theories.

Contribution

It provides a general solution framework for sudden singularities in both standard and modified gravity Friedmann universes, extending previous specific models.

Findings

Sudden singularities occur with finite scale factor and density but divergent pressure and acceleration.

The phenomenon is shown to exist in both general relativity and theories with analytic functions of scalar curvature.

The solutions encompass a wide range of conditions leading to sudden singularities.

Abstract

We present a general form for the solution of an expanding general-relativistic Friedmann universe that encounters a singularity at finite future time. The singularity occurs in the material pressure and acceleration whilst the scale factor, expansion rate and material density remain finite and the strong energy condition holds. We also show that the same phenomenon occurs, but under different conditions, for Friedmann universes in gravity theories arising from the variation of an action that is an arbitrary analytic function of the scalar curvature.