© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
October 04, 2011
2011 Physics Nobel Prize for Studies of the Universe
The 2011 Nobel Prize in Physics has been awarded to Saul Perlmutter (USA), Brian P. Schmidt (Australia) and Adam G. Riess (USA) for the discovery of the accelerating expansion of the Universe. The scientists reached their conclusions, which first came as a surprise to the physical community, on the basis of measurements carried out on distant exploding stars, called supernovae.
According to the prevailing cosmological model, the expansion of the Universe began with the Big Bang about 13.7 billion years ago, but slowed down during the first several billion years. Eventually, the expansion started to accelerate, which is believed to be caused by the so-called dark energy, a hypothetical form of energy that fills the universe and currently accounts for about 73% of its total mass and energy. At the beginning, this dark energy constituted only a small part of the Universe. But as matter got diluted by the expansion, the dark energy became more dominant, causing the acceleration. Today, this unknown form of energy is one of the greatest enigmas in physics.
The findings of this year's Nobel Laureates, published in 1998 by two different research groups, have helped unveil a Universe that –to a large extent– is still unknown. Saul Perlmutter headed one of the two research teams and Brian Schmidt was the leader of the second one, where Adam Riess was to play a crucial role.
The two groups used a particular kind of supernova, called type Ia supernova, and found over 50 distant exploding stars whose light was weaker than expected. This was a sign that the expansion of the Universe was accelerating.
Image: Nobel Medal (© ® The Nobel Foundation). Source: nobelprize.org