Saul Perlmutter Wins Nobel Prize

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Scientist and 2011 Nobel Prize winner Saul Perlmutter Lawrence Berkeley National Lab - Roy Kaltschmidt, photographer

Saul Perlmutter

Science is all about opening eyes and expanding horizons. That's especially true for Dr. Saul Perlmutter in the Office of Science's Lawrence Berkeley National Laboratory, who was recently named the winner of the 2011 Nobel Prize in Physics.

Dr. Perlmutter, who shared the Nobel Prize with Brian Schmidt and Adam Riess, looked up to the skies and found something astonishing: The universe is expanding…and at an accelerating rate. That simply isn't supposed to happen. According to the accepted theory of the time, the great expansion that began at the beginning of the universe (the Big Bang) would eventually slow down, as gravity exerted a tenuous but inexorable pull on the planets and stars and galaxies.

The theory made perfect cosmological common sense…it just didn't fit Dr. Perlmutter's observations. To study the expected rate of deceleration, he and his fellow Nobel Laureates observed the behavior of distant stars. Specifically, they studied a special class of exploding stars known as Type Ia supernovae. Those stars are thought to explode in about the same way, and so the dimmer they are, the more distant they are. (Nighttime drivers do something similar while estimating the distance to other cars.)

Dr. Perlmutter and his team have also used the powerful supercomputers at Berkeley Lab's National Energy Research Scientific Computing Center (NERSC) to hone and refine their data; to reduce potential experimental errors, and to improve the comparisons between near and distant Type Ia supernovae. This increased the confidence in their original results, which were utterly unexpected.

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Scientist Saul Perlmutter sitting atop a ladder with a large image of the universe in the background Lawrence Berkeley National Lab - Roy Kaltschmidt, photographer

Saul Perlmutter heads the Supernova Cosmology Project at Lawrence Berkeley National Laboratory. It was this team along with the High-z Supernova Search Team which found evidence of the accelerating expansion of the universe.

In studying distant supernovae, Dr. Perlmutter discovered that they weren't slowing down as they moved away, but rather were zooming out at an accelerating rate. Imagine if the apple that allegedly dropped on Isaac Newton's head – and thereby gave him the idea for gravity – instead leaped upward into the sky. (Newton's perspective would have changed…as would have the apple's!) But as Dr. Perlmutter found, that accelerating expansion seems to be happening on large scales, and it seems to be driven by a phenomena we now know as dark energy.

Scientists have measured that dark energy makes up some 70 percent of the mass-energy in the universe—a huge fraction of everything that's out there. But they still don't know what it actually is. As the Nobel Committee noted, "It is an enigma, perhaps the greatest in physics today."

It's a mystery that Dr. Perlmutter, who also leads the International Supernova Cosmology Project, continues to study. And the insights he and others gain could prove almost as surprising as their original findings. That's what the Office of Science is all about: The brightest minds using the best tools to transform our view of the world; to make us see further, and aim higher.

So congratulations to Dr. Perlmutter and his fellow Physics Nobel Laureates. They've opened our eyes, expanded our horizons and made us see an expanding, and accelerating, universe.

For more information on Dr. Perlmutter and his Nobel Prize, please go to: and And for more information on DOE's Office of Science, please go to:

Charles Rousseaux is a Senior Writer in the Office of Science.