Models of the early universe and the origin of structure

Inflation is a period of the very early universe during which the universe undergoes an extremely rapid expansion. Vacuum fluctuations of any light scalar field are enlarged by the expansion and generate the primordial density perturbations of the universe on all scales. This thesis is about these perturbations generated during inflation and their observational consequences. After introducing inflationary cosmology we calculate the power spectra of primordial curvature and isocurvature perturbations from a general two field inflation model including next-to-leading order correction terms in a slow-roll expansion.EThOS - Electronic Theses Online ServiceGBUnited Kingdo