FRW Universe Models in Conformally Flat Spacetime Coordinates. II: Universe models with negative and vanishing spatial curvature

TL;DR

This paper derives general expressions for universe models with negative and zero spatial curvature in conformally flat coordinates, exploring their properties, horizons, and matter creation phenomena.

Contribution

It provides new formulations of FRW universe models with negative and zero curvature in conformally flat coordinates, including analysis of horizons and matter creation.

Findings

Continual creation of space, matter, and energy in negative curvature models.

Existence of particle horizons in these models.

Explicit models with dust, radiation, and vacuum energy.

Abstract

We deduce general expressions for the line element of universe models with negative and vanishing spatial curvature described by conformally flat spacetime coordinates. The empty Milne universe model and models with dust, radiation and vacuum energy are exhibited. Discussing the existence of particle horizons we show that there is continual creation of space, matter and energy when conformal time is used in Friedmann-Robertson-Walker models with negative spatial curvature.