The accelerated universe. On the Nobel Prize in Physics 2011 awarded to Saul Perlmutter, Brian P. Schmidt, and Adam G. Riess

Abstract

Since the end of the 1920s we have known that distant galaxies are receding from us. The observations that led to this conclusion were mainly those of Edwin Hubble. The history of the universe has been one of continuous expansion and cooling, marked by several critical events. In a matter-dominated universe, it is quite intuitive that the expansion will eventually slow down; in other words, the universe should decelerate. And yet two teams, the Supernova Cosmology Project and the High-z Supernova Search Team, used a subset of supernova-type Ia (SNIa)-and reached the same surprising result: the universe is accelerating. But what, then, is producing theobserved cosmological acceleration? This article discusses the 2011 Nobel Prize for Physics, awarded to Saul Perlmutter, Brian P. Schmidt, and Adam G. Riess for the discovery of the accelerating expansion of the universe through observations of distant supernovae, and reviews the cosmological context of the discovery and the use of supernovae as standard candles. Some of the consequences of the discovery are presented as well.