A Spherically Symmetric Closed Universe as an Example of a 2D Dilatonic Model

TL;DR

This paper analyzes a 2D dilatonic gravity model that, when interpreted in four dimensions, describes a closed, spherically symmetric universe with specific dynamic properties, providing insights into simplified cosmological scenarios.

Contribution

It presents the general solution of a 2D dilatonic model with spherical symmetry and interprets it as a closed universe in four dimensions.

Findings

The model admits static and homogeneous solutions.

The homogeneous solution describes a closed universe.

The solutions involve null dust streams with spherical symmetry.

Abstract

We study the two-dimensional (2D) dilatonic model describing a massless scalar field minimally coupled to the spherically reduced Einstein-Hilbert gravity. The general solution of this model is given in the case when a Killing vector is present. When interpreted in four dimensions, the solution describes either a static or a homogeneous collision of incoming and outgoing null dust streams with spherical symmetry. The homogeneous Universe is closed.