Cosmology of the Very Early Universe

TL;DR

This paper reviews early universe models, including inflation, Matter Bounce, and String Gas Cosmology, focusing on their ability to explain large-scale structure and connect to observations through cosmological perturbations.

Contribution

It provides a comprehensive survey of inflationary and alternative early universe scenarios, highlighting recent progress and unresolved issues.

Findings

Inflation explains large-scale structure but has unresolved problems.

Alternative models like Matter Bounce and String Gas Cosmology are viable options.

Cosmological perturbation evolution links models to observable data.

Abstract

In these lectures I focus on early universe models which can explain the currently observed structure on large scales. I begin with a survey of inflationary cosmology, the current paradigm for understanding the origin of the universe as we observe it today. I will discuss some progress and problems in inflationary cosmology before moving on to a description of two alternative scenarios - the Matter Bounce and String Gas Cosmology. All early universe models connect to observations via the evolution of cosmological perturbations - a topic which will be discussed in detail in these lectures.