The Early Universe as a Window to Quantum Gravity

Louisiana State University, Baton Rouge LA

Investigators

Abstract

Recent observations have been able to detect remnants of physical processes that occurred a tiny fraction of second after the so-called big bang. On the theoretical side our understanding of the cosmic evolution although quite sophisticated is still incomplete. A deep understanding of how to make Einstein's theory of gravity and quantum mechanics consistent is needed to describe the very early universe, and such a theory is not fully developed yet. This project seeks to contribute to filling this gap by incorporating ideas and techniques of quantum gravity to cosmology with the goal of overcoming limitations of current models. The objective of this project is therefore twofold: to extend our understanding of the origin and fate of the universe, and to confront new quantum-gravity ideas with the last generation of observations. The proposed research aims at developing approximate methods to incorporate quantum gravity physics in models of the early universe. Investigations will focus on theoretical as well as phenomenological aspects of quantum cosmology, with special emphasis on techniques coming from loop quantum gravity. From the theoretical point of view, it will be explored how matter fields propagate on regimes in which the quantum aspects of gravity are important, and the way in which the familiar quantum field theory in curved space-times emerges from the more fundamental theory. From the phenomenological viewpoint, the resulting theoretical framework will be applied to extend cosmological models to include Planck scale physics. Investigations will cover scalar perturbations that are responsible for the temperature anisotropies in the cosmic microwave background and galaxy distribution, non-Gaussianity, primordial magnetic fields, and particular attention will be paid to gravitational waves generated in the early universe.