Dark energy takes over: the expansion of the universe, which has always slowed down (due to gravity), is now beginning to accelerate. The universe is 57% of its current size. 4.5 billion years later, three teams of world-class supernova hunters led by Saul Perlmutter of Lawrence Berkeley Laboratories in California, Brian Schmidt and Robert Kirschner in Australia, and the High-z Supernova Project led by Adam Riess of Harvard University, discover that the expansion of the universe is accelerating.
