By Doug Oakley
Staff Writer
A UC Berkeley astrophysicist received the 2011 Nobel Prize in Physics Tuesday for proving that the universe is expanding at an ever increasing rate, rather than shrinking toward an eventual collapse, a concept even other scientists have difficulty wrapping their heads around.
Saul Perlmutter, 52, who works at the Lawrence Berkeley National Laboratory and is a professor of physics at UC Berkeley, took one half of the $1.5 million prize, while the other half is shared by competing researchers Adam Riess, 41, of The Johns Hopkins University and Brian Schmidt, 44 of Australian National University.
Both Perlmutter and the other two scientists were working on the same problem at the same time.
Perlmutter said during a Tuesday press conference that he and other scientists proved the universe is expanding at an increasing rate by examining streams of light coming from exploding stars, or supernovae, billions of light years from earth.
The stretched-out streams of light, which change color as they come across the universe, were picked up by telescopes and used as yardsticks to measure the accelerating expansion of the universe.
“Because we had developed a technique to find supernovae using computers and cameras in a more organized way, we tried to find supernovae father away that could act as markers,” Perlmutter said, “In the end all we had to do was plot the stretch of the universe (by studying) the light.”
He said a scientist can tell how far away an exploding star is by how faint the light is.
“Then you can say, ‘this one has been traveling 2 billion years and that one 4 billion and this one is farther away than that one,’” Perlmutter said. “Light leaves supernovae looking mostly blue, but by the time it reaches us it has changed and has been stretched along with the rest of the universe.”
The concept is contrary to previous ideas in which scientists believed that the universe initially expanded after a big bang and that the expansion started to slow, or de-accelerate. From that belief they theorized that it would then start shrinking and collapse on itself.
But what Perlmutter found and what Robert Cahn, head of the cosmology department at the lab, called “the biggest discovery in the history of science,” is the exact opposite.
“You might expect the expansion would be slowing down because all the stuff in the universe is attracted to each other,” Perlmutter said. “Would it then slow down and come to a halt and collapse and the universe would come to an end?”
The answer, he now knows, is no.
Even other scientists scratch their heads when they think of the concept for which Perlmutter was awarded the prize.
David Schlegel, a senior scientist in the physics division who works down the hall from Perlmutter, said the concept is “just weird” and counterintuitive, even to the brainiest.
“It’s like you take an apple and throw it up in the air and rather than seeing it fall back down to Earth, it zooms off into infinity,” said Schlegel. “At the time of the first discovery on this, I didn’t believe it. I just thought they had done something wrong.”
He added that “we have not yet figured out,” how it affects people on Earth.
Don DePaolo, associate director of the lab, said Perlmutter proved “the exact opposite of what was expected.”
“We hope this award sparks the imagination of young would-be scientists everywhere who look up into the night’s sky and wonder what they see,” DePaolo said.
Perlmutter’s work brings up other unanswered questions about dark matter and dark energy.
“There are two vast unknowns we have identified in cosmology,” Perlmutter said. “One is that 20 percent of the universe is dark matter, and we know it exists because it holds galaxies together. And 73-75 percent of the universe is dark energy that is responsible for causing the universe to expand faster and faster, but we have no good tie between them, so we’re looking for a theoretical concept there.”
Perlmutter also didn’t know how his discovery could be used here on the ground, but he does know scientific discoveries are often used to solve problems in completely unrelated areas.
“We have no idea whether or not we will be able to use this knowledge to do something magical,” Perlmutter said. “But in the past we have been able to do more with our discoveries. It’s the only way we can proceed as scientists.”
Doug Oakley covers Berkeley. Contact him at 510-843-1408. Follow him at Twitter.com/douglasoakley
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