Universe Models with a Variable Cosmological "Constant" and a "Big Bounce"

TL;DR

This paper introduces exact cosmological solutions featuring a variable cosmological constant derived from higher dimensions, supporting a non-singular big bounce and aligning with observational data and string theory extensions.

Contribution

It presents a new class of solutions with a variable cosmological constant and a non-singular big bounce, bridging observational cosmology and higher-dimensional theories.

Findings

Supports a non-singular big bounce instead of a big bang.

Incorporates a variable cosmological constant from higher dimensions.

Aligns with observational data and string theory extensions.

Abstract

We present a rich class of exact solutions which contains radiation-dominated and matter-dominated models for the early and late universe. They include a variable cosmological ``constant'' which is derived from a higher dimension and manifests itself in spacetime as an energy density for the vacuum. This is in agreement with observational data and is compatible with extensions of general relativity to string and membrane theory. Our solutions are also typified by a non-singular ``big bounce'' (as opposed to a singular big bang), where matter is created as in inflationary cosmology.