abstract:The accelerating universe is the observation that the universe appears to be expanding at an increasing rate. In formal terms, this means that the cosmic scale factor a(t) has a positive second derivative, so that the velocity at which a distant galaxy is receding from us should be continuously increasing with time.
Riess shared this year's prize with with fellow American Saul Perlmutter and the Australian Brian Schmidt for the discovery, back in 1998, that the expansion of the Universe is accelerating.
When it's bolted onto the Blanco Telescope at the Cerro Tolodo Observatory in Chile next month the 570-megapixel Dark Energy Camera will survey some 300 million galaxies in the southern sky, measuring the speed at which they are moving apart with phenomenal accuracy, and giving the best description yet of the accelerating expansion of the Universe.
The list of top discoveries made with Hubble reads like the hit parade of astronomy: a mysterious new "dark energy" causing the accelerating expansion of the universe, distances to other galaxies, the supermassive black holes at their centers, the age of the universe, planet formation around other stars, searches for signs of extraterrestrial life -- and the list goes on.