Discovery of Cosmic Acceleration

Abstract

Recognizing that the expansion of the universe is accelerating due to dark energy was one of the most fundamental and exciting discoveries of the twentieth century. Two teams of scientists took advantage of advances in detector technology and improved understanding of supernovae to map the expansion history of the universe half way back to the Big Bang. Their original goal was to estimate the mass density of the universe, but as their measurements became more precise, they were eventually faced with the need to radically change the standard model of cosmology.