Exponential Potential Embryo Dynamics Of The Universe

Since Gamow proposed the explosion cosmology in the end of 1940s, people never stop studying on this new subject. With the development of the observation, we get more and more accurate data and realize that the universe is dominated by the dark energy and dark matter. Though the observation data shows the existence of the dark energy, we can't observe it directly. The nature of the dark energy remains a mystery. Various models of dark energy have been proposed.In this paper, we investigate some interesting models of dark energy, especially the brane scenario, in which our four dimensional universe is embedded in a higher dimensional spacetime where the gravitation can propagate in. Since the effect of the extradimension can't be obtained by experiment exactly, the brane world models admit a much wider range of possibilities for dark energy. It forces the scientists to untie the mystery.There are lots of dark energy models under the framework of brane world scenario. In this paper we will mainly discuss the Randall-Sundrum2 model and the Dvali-Gabadadze-Porrati model. The structure of the paper is arranged as follows:In chapter1&2, I review the history of the universe and the result of observation;In chapter3, I report the achievement in theoretical study of dark energy,emphasizing on several typical models;In chapter 4, I study the development of the brane scenario and summarize several major brane models;The main work of this thesis is in chapter 5&6 in which I describe the property of RS2 model and DGP model. For example, we analyse the dynamical evolution of the exponential potential model. And we find that the dynamical attractor caused by exponential potential can make the late time behavior insensitive to the initial condition that is helpful to avoid the fine tuning problem. In addition, we find the standard DGP model has a late-time self-acceleration solution and its equation of state w