The cosmological constant filter without big bang singularity

TL;DR

This paper explores a modified gravity model that acts as a cosmological constant filter, replacing the big bang singularity with a cosmic bounce and ensuring finite energy density and curvature at early times.

Contribution

It demonstrates that the CC filter mechanism can eliminate the big bang singularity, replacing it with a bounce where physical quantities remain finite.

Findings

Big bang singularity replaced by a cosmic bounce.

Finite matter energy density and curvature at early times.

The finiteness can be observed algebraically in certain cases.

Abstract

In the recently proposed cosmological constant (CC) filter mechanism based on modified gravity in the Palatini formalism, gravity in the radiation, matter and late-time de Sitter eras is insensitive to energy sources with the equation of state -1. This implies that finite vacuum energy shifts from phase transitions are filtered out, too. In this work we investigate the CC filter model at very early times. We find that the initial big bang singularity is replaced by a cosmic bounce, where the matter energy density and the curvature are finite. In a certain case this finiteness can be observed already on the algebraic level.