## An Introduction to Large Scale Structure

##### Summary

With the development of more and more large scale surveys in the past few years, and the years to come, the importance of understanding the large scale structure of the universe is steadily increasing. Without an effective model to describe this structure we would not be able to glean all the information we can from the surveys, wasting their potential. In this work some of the dynamics behind the evolution of large scale structures will be explained, as well as methods to accurately study this in both the linear and the perturbative nonlinear regime, using Standard Perturbation Theory and the Effective Field Theory of Large Scale Structure. From this we will find that using either method we can compute the time dependence of the density contrast perturbatively. The EFToLSS will be more accurate but needs more information to determine important parameters like the speed of sound and equation of state. We will also look at an elaboration on the theory by considering some of the implications from General Relativity. Here the most important result will be a motivation why using a Newtonian approximation in the first chapters of the thesis is warranted. After this a simplification of the theory is considered in the form of Spherical Collapse, where it will be shown that the importance of the growing mode in linear SPT with respect to higher order modes depends highly on the begin conditions.