Universal Approach to Cosmological Singularities in Two Dimensional Dilaton Gravity

TL;DR

This paper investigates the nature of cosmological singularities in two-dimensional dilaton gravity models with matter, revealing a universal threshold for singularity formation and the influence of quantum states on singularity persistence.

Contribution

It introduces a model-independent threshold for singularities in semiclassical solutions and analyzes how quantum states affect singularity existence in non-conformal matter cases.

Findings

Weak coupling singularity occurs below a matter threshold.

Singularity persistence depends on the quantum state chosen.

Universal behavior observed across different models.

Abstract

We show that in a large class of two dimensional models with conformal matter fields, the semiclassical cosmological solutions have a weak coupling singularity if the classical matter content is below a certain threshold. This threshold and the approach to the singularity are model-independent. When the matter fields are not conformally invariant, the singularity persists if the quantum state is the vacuum near the singularity, and could dissappear for other quantum states.