Presents part of course, Frontiers and controversies in Astrophysics, when Professor Bailyn explained reasons for the expansion of the universe are addressed at the start of this lecture, focusing especially on the acceleration of dark energy. Supernovae are the first evidence for the existence of dark energy, and two other proofs are presented: the first is the Cosmic Microwave Background and Secondly, Large-Scale Clustering . Computer simulations of the evolution of the universe are shownEducação Superior::Ciências Exatas e da Terra::Astronomia