Three U.S.-born scientists win the Nobel Prize in physics

By KARL RITTER and LOUISE NORDSTROM
The Associated Press

STOCKHOLM — Three U.S.-born scientists won the Nobel Prize in physics on Tuesday for their studies of exploding stars that revealed 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. Working in two separate research teams during the 1990s — Perlmutter in one and Schmidt and Riess in the other — the scientists raced to map the universe’s expansion by analyzing a particular type of supernovas, or exploding stars.

They found that the light emitted by more than 50 distant supernovas was weaker than expected, a sign that the universe was expanding at an accelerating rate, the academy said.

“For almost a century the universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago,” the citation said. “However the discovery that this expansion is accelerating is astounding. If the expansion will continue to speed up the universe will end in ice.”

Perlmutter, 52, heads the Supernova Cosmology Project at the University of California, Berkeley. He was born in Champaign-Urbana.

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

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

The academy said the three researchers were stunned by their own discoveries — they had expected to find that the expansion of the universe was slowing down. But both teams reached the opposite conclusion: far-away galaxies were racing away from each other at an ever-increasing speed.

The acceleration is believed to be driven by dark energy, one of the great mysteries of the universe.

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