Three U.S.-born scientists whose work showed that the universe's expansion is accelerating have won the 2011 Nobel Prize for Physics.
During the 1990s, the scientists found that the light from more than 50 distant supernovas (exploding stars) was weaker than expected, which signaled that these more distant objects were moving faster than nearer ones. And that meant that the universe's expansion is constantly speeding up.
The Nobel committee, in its statement, 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. 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 committee also noted that even the Laureates themselves were surprised by their discovery, because they had expected to find the universe's expansion was slowing down.
The three studied a supernova called a 1a supernova, which, the committee said in its statement, "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 driver of the expansion is one of the greatest puzzles of physics. It is thought to be dark energy that makes up three-quarters of the universe, though what dark energy is exactly remains unknown. The Nobel committee concluded, "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."
Perlmutter, 52, heads the Supernova Cosmology Project at the University of California, Berkeley.
Schmidt, 44, leads 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.
photo: A 1a supernova shown in optical, ultraviolet and X-ray wavelengths. (NASA/Swift/S. Immler)
For news about yesterday's announcement of winners of the 2011 Nobel Prize in medicine, click here.
And to find out who "won" last week's Ig Nobels, which celebrate the silliest science of the last year, click here.