Reported by Amy Standen and Gabriela Quirós, Quest
At this morning’s press conference at Lawrence Berkeley National Laboratory, newly-minted Nobel laureate, astrophysicist Saul Perlmutter said what attracted him to his work initially was that it took a scientific approach to a philosophical question: What is the fate of the universe?
Since astronomer Edwin Hubble’s observations in 1929, scientists have known that the universe appears to be expanding, pushing outwards and becoming thinner, like a stretched T-shirt.
Perlmutter, and others, assumed that the rate of this expansion must be slowing down, dragged down by the force of gravity.
“The obvious question,” said Perlmutter, “was how much is it slowing down? Is it slowing enough that it could slow down to the point where it would come to a halt someday and perhaps turn around and collapse? In which case, we could discover that the universe was really coming to an end.”
Perlmutter and his colleagues at the Berkeley Lab’s Supernova Cosmology Project came up with a method to test their question. They located a type of distant stars called Type 1a supernovae and measured how much the stars’ light shifted towards the red wavelengths as it traveled through the universe. That calculation showed how long ago the stars had exploded and allowed them to create a history of the expansion of the universe.
What they found when they crunched the numbers was surprising. The light from many supernovae was actually weaker than expected, a sign that the universe’s speed of expansion was accelerating, not slowing down.
Some mysterious force was driving this accelerated expansion. Scientists called the force “dark energy.” The name is a “placeholder,” said Perlmutter, because scientists don’t understand what it is.
When it announced the prize early this morning, the Royal Swedish Academy of Sciences called dark energy perhaps the greatest enigma in physics today.
This year’s Nobel Prize in Physics was awarded to Perlmutter, who is an astrophysicist at the Berkeley Lab and a professor at Cal, and to Brian P. Schmidt, of the Australian National University in Weston Creek, and Adam G. Riess, of the Space Telescope Science Institute and Johns Hopkins University in Baltimore. Half of the $1.4 million award will go to Perlmutter, and the other half will be split by Riess and Schmidt.