Cosmological Perturbation Theory

Abstract

This study is a review of Cosmological perturbation theory. The theory aims to model the physical universe by perturbing about a background Friedmann-Robertson-Walker cosmological model. Two approaches are highlighted, The gauge-invariant formalism, and the gauge fixed (Conformal newtonian gauge) approach. Boltzman equations for all the matter components of the universe are studied. The study gives a set of linear differential equations. The initial conditions and the origin of fluctuations lead to the study of scalar field inflation. Future directions include quantum gravity corrections, alternative inflationary models and the study of inhomogeneity and isotropy in concordance with current day observations.