Quantum Gravity, Time, Bounces and Matter

TL;DR

This paper explores how non-classical quantum states of the universe, including bounce scenarios, can influence inflationary perturbations and primordial spectra, highlighting effects often neglected in classical models.

Contribution

It investigates the impact of a non-semiclassical wave-function and bounce phenomena on early universe inflationary perturbations within Quantum Cosmology.

Findings

Bounce scenarios can cause interference effects affecting primordial spectra

Quantum gravitational effects may alter trans-Planckian mode dynamics

Non-classical states influence the evolution of inflationary perturbations

Abstract

In the context of Quantum Cosmology and the Wheeler-DeWitt equation we investigate the possible effects of a non semiclassical wave-function of the universe on the evolution of the inflationary perturbations. These are associated with the quantum behaviour of the homogenous degrees of freedom (in particular the radius of the universe) in the early stages of the inflationary expansion, which in turn can affect the dynamics of the trans-Planckian modes of the fields present. The existence of a bounce for the homogeneous gravitational wave-function is studied. This can lead to an interference between a contracting and an expanding universe and, as a consequence, to the above quantum gravitational effects on the primordial spectra. In the traditional study of the inflationary fluctuations such effects are neglected and a quasi-classical behaviour for the homogeneous inflaton-gravity system is taken.