“Why is the universe speeding up?
In 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. Yet, according to Einstein’s theory of General Relativity, gravity should lead to a slowing of the expansion. To explain cosmic acceleration, cosmologists are faced with two possibilities: Either 75% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.
The Dark Energy Survey (DES) is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 120 scientists from 23 institutions in the United States, Brazil, Spain, Germany and the United Kingdom are working on the project. This collaboration is building an extremely sensitive 570-Megapixel digital camera, DECam, and will mount it on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes. Starting in late 2011 and continuing for five years, DES will survey a large swath of the southern sky out to vast distances in order to provide new clues to this most fundamental of questions. ”