Standard Cosmology Delayed

TL;DR

Introducing a delay in the Friedmann equation can naturally produce early accelerated expansion in the universe without requiring scalar field inflation, potentially simplifying cosmological models.

Contribution

This paper proposes a delayed Friedmann equation model that explains early universe acceleration without scalar fields, offering an alternative to inflation.

Findings

Delayed Friedmann equation induces early accelerated expansion.

The model transitions smoothly to standard decelerated expansion.

Inflation can occur without violating energy conditions.

Abstract

The introduction of a delay in the Friedmann equation of cosmological evolution is shown to result in the very early universe undergoing the necessary accelerated expansion in the usual radiation (or matter) dominated phase. Occurring even without a violation of the strong energy condition, this expansion slows down naturally to go over to the decelerated phase, namely the standard Hubble expansion. This may obviate the need for a scalar field driven inflationary epoch.