A radiation-like era before inflation

TL;DR

This paper proposes a model where a radiation-like era precedes inflation, driven by non-adiabatic effects in the Wheeler-DeWitt equation, suggesting a transition from a radiation-dominated phase to inflation.

Contribution

It introduces a semiclassical approach to quantum cosmology showing a radiation-like initial phase before inflation, a novel perspective on early universe evolution.

Findings

Identifies a radiation-like era driven by non-adiabatic gravitational effects.

Shows the transition from radiation-like expansion to inflation.

Provides a quantum cosmological framework for pre-inflationary dynamics.

Abstract

We show that the semiclassical approximation to the Wheeler-DeWitt equation for the minisuperspace of a minimally coupled scalar field in the spatially flat de Sitter Universe prompts the existence of an initial power-law evolution driven by non-adiabatic terms from the gravitational wavefunction which act like radiation. This simple model hence describes the onset of inflation from a previous radiation-like expansion during which the cosmological constant is already present but subleading.