Trio win physics Nobel for studying universe's expansion

The laureates studied several dozen exploding stars, called supernovae and made the discovery

By Ankur Paliwal
Published: Tuesday 04 October 2011

Three US scientists who discovered that our Universe's expansion is accelerating have been awarded this year's Nobel prize for physics.

Saul Perlmutter of the Lawrence Berkeley National Laboratory ofUniversity of California, Brian P Schmidt of Australian National University, and Adam G Riess of Johns Hopkins University and senior member of Science staff at Space Telescope Science Institute, both in Baltimore, will share the prize money of US $1.5 million.

The laureates 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, read a statement released by the The Royal Academy of Sciences.

In 1998, cosmology was shaken by its foundation when two research teams presented their findings. Headed by Perlmutter, one of the teams had set to work in 1988. Schmidt headed another team, launched at the end of 1994, where Riess played 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 Ia. 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. 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.

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 continues to speed up, the Universe will end in ice, scientists say.

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.

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