The pre-inflationary dynamics of loop quantum cosmology: Confronting quantum gravity with observations

TL;DR

This paper applies loop quantum gravity techniques to early universe cosmology, exploring pre-inflationary dynamics, resolving trans-Planckian issues, and identifying potential observational signatures of quantum gravity effects.

Contribution

It extends the inflationary paradigm to include the Planck era using loop quantum gravity, revealing new effects and observational prospects.

Findings

A self-consistent extension of inflation over 11 orders of magnitude in density and curvature.

Potential modifications to the tensor-to-scalar ratio and spectral index relations.

New sources of non-Gaussianities linked to quantum gravity effects.

Abstract

Using techniques from loop quantum gravity, the standard theory of cosmological perturbations was recently generalized to encompass the Planck era. We now apply this framework to explore pre-inflationary dynamics. The framework enables us to isolate and resolve the true trans-Planckian difficulties, with interesting lessons both for theory and observations. Specifically, for a large class of initial conditions at the bounce, we are led to a self consistent extension of the inflationary paradigm over the 11 orders of magnitude in density and curvature, from the big bounce to the onset of slow roll. In addition, for a narrow window of initial conditions, there are departures from the standard paradigm, with novel effects ---such as a modification of the consistency relation between the ratio of the tensor to scalar power spectrum and the tensor spectral index, as well as a new source for non-Gaussianities--- which could extend the reach of cosmological observations to the deep Planck regime of the early universe.