By DENNIS OVERBYE
Published: October 4, 2011
Three astronomers won the Nobel prize on Tuesday for discovering that the universe is apparently being blown apart by a mysterious force that cosmologists now call dark energy. They are Saul Perlmutter of the Lawrence Berkeley National Laboratory in Berkeley, Calif., Brian P. Schmidt of the Australian National University in Weston Creek, Australia, and Adam G. Riess of the Space Telescope Science Institute and Johns Hopkins University in Baltimore.
They were the leaders of two competing teams of astronomers who were trying to use the exploding stars known as Type 1a supernovae as cosmic lighthouses to measure the expansion of the universe. They were hoping to measure how fast the universe, which has been expanding since its fiery birth in the Big Bang 14 billion years ago, was slowing down, and thus to find out if its ultimate fate was to fall back together in what is called a Big Crunch or not. Instead, they reported in 1998, it was inexplicably speeding up, a conclusion that nobody would have accepted if not for the fact that both groups wound up with the same answer.
At the time, “We were a little scared,” Dr. Schmidt said. Subsequent cosmological measurements have confirmed that roughly 70 percent of the universe by mass or energy consists of this antigravitational dark energy.
The most likely explanation for this bizarre behavior is a fudge factor Albert Einstein introduced into his equations in 1917 to stabilize he universe against collapse and then abandoned as his greatest blunder. “Every test we have made has come out perfectly in line with Einstein’s original cosmological constant in 1917,” Dr. Schmidt said.
more
http://www.nytimes.com/2011/10/05/science/space/05nobel.html