Discovery of ‘accelarating expansion of the universe’ wins Physics Nobel

Three U.S.-born scientists won the Nobel Prize in physics on Tuesday for a study of exploding stars that discovered that the expansion of the universe is accelerating.

The Royal Swedish Academy of Sciences said American Saul Perlmutter would share the 10 million kronor ($1.5 million) award with U.S.-Australian Brian Schmidt and U.S. scientist Adam Riess “for the discovery of the accelerating expansion of the universe through observations of distant supernovae.”

Their discoveries “have helped to unveil a universe that to a large extent is unknown to science,” the citation said.

Mr. Perlmutter, 52, heads the Supernova Cosmology Project at the University of California, Berkeley.

Mr. Schmidt, 44, is the head of the High-z Supernova Search Team at the Australian National University in Weston Creek, Australia.

Mr. Riess, 42, is an astronomy professor at Johns Hopkins University and Space Telescope Science Institute in Baltimore, Maryland.

Excerpts from the Nobel

Excerpts from the citation awarding the 2011 Nobel Prize in physics to Mr. Perlmutter, who shared it with Mr. Schmidt and Mr. Riess “for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.”

“They have studied several dozen exploding stars, called supernovae, and discovered that the Universe is expanding at an ever—accelerating rate. The discovery came as a complete surprise even to the Laureates themselves.”

“In 1998, cosmology was shaken at its foundations as two research 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.”

“The teams used a particular kind of supernova, called type Ia supernova. It is an explosion of an old compact star that 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. 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.”

AP

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