Theory of Cosmological Perturbations and Applications to Superstring Cosmology

TL;DR

This paper reviews the theory of cosmological perturbations, from Newtonian to quantum levels, and discusses their applications in inflationary cosmology to connect fundamental physics with observations.

Contribution

It provides a comprehensive introduction to cosmological perturbation theory and explores its application to testing Planck-scale physics via inflation.

Findings

Inflationary cosmology can be tested through fluctuation evolution.

Quantum perturbation theory bridges fundamental physics and observations.

Applications demonstrate the connection between string theory and cosmological data.

Abstract

The theory of cosmological perturbations is the main tool which connects theories of the early universe (based on new fundamental physics such as string theory) with cosmological observations. In these lectures, I will provide an introduction to this theory, beginning with an overview of the Newtonian theory of fluctuations, moving on to the analysis of fluctuations in the realm of classical general relativity, and culminating with a discussion of the quantum theory of cosmological perturbations. I will illustrate the formalism with applications to inflationary cosmology. I will review the basics of inflationary cosmology and discuss why - through the evolution of fluctuations - inflation may provide a way of observationally testing Planck-scale physics.