THE ROYAL SWEDISH ACADEMY OF SCIENCES has awarded the Nobel Prize in Physics for 2011 to the leaders of the teams that discovered the accelerating expansion of the universe.
One half of the prize has been awarded to Saul Perlmutter (The Supernova Cosmology Project, Lawrence Berkeley National Laboratory and University of California) and the other half jointly to Brian P. Schmidt (The High-z Supernova Search Team, Australian National University, Australia) and Adam G. Riess (The High-z Supernova Search Team, Johns Hopkins University and Space Telescope Science Institute, Baltimore, USA).
In 1998, cosmology was shaken at its foundations as the two teams presented their findings. Headed by Saul Perlmutter, one of the teams had set to work in 1988. Brian Schmidt headed another team, launched at the end of 1994, where Adam Riess was to play a crucial role.
The research teams raced to map the Universe by locating the most distant supernovae (exploding stars). More sophisticated telescopes on the ground and in space, as well as more powerful computers and new digital imaging sensors, opened the possibility in the 1990s to add more pieces to the cosmological puzzle.
The teams used a particular kind of supernova, called type Ia supernova. It is an explosion of an old compact starthat is as heavy as the Sun but as small as the Earth. A single such supernova can emit as much light as a whole galaxy.
Greatest enigma in physics
All in all, the two research teams found over 50 distant supernovae whose light was weaker than expected—this was a sign that the expansion of the Universe was accelerating.
The potential pitfalls had been numerous, and the scientists found reassurance in the fact that both groups had reached the same astonishing conclusion.
For almost a century, the Universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago. However, the discovery that this expansion is accelerating is astounding. If the expansion will continue to speed up the Universe will end in ice.
The acceleration is thought to be driven by dark energy, but what that dark energy is remains an enigma—perhaps the greatest in physics today.
What is known is that dark energy constitutes about three quarters of the Universe.
Therefore the findings of the 2011 Nobel Laureates in Physics have helped to unveil a Universe that to a large extent is unknown to science. And everything is possible again.
More information: Check out this great video on dark energy and the expansion of the universe. It features one of the Nobel Prize winners, Saul Perlmutter.
Adapted from information issued by the Royal Swedish Academy of Sciences.
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