Nobody knows what's driving the accelerating expansion of the universe. Until recently, no one even suspected that the universe is accelerating! Berkeley Lab scientists led the way to that surprising discovery, and they are leading the effort to determine the nature of the "dark energy" that is stretching space-time itself.
Astrophysicist Saul Perlmutter leads the international Supernova Cosmology Project headquartered at Berkeley Lab.
He says that as a child, "I always enjoyed looking at the sky, but I was never one of those people who had their own backyard telescope. It was only because I started needing telescopes to answer the fundamental questions that I started learning much about astronomy."
After graduating from Harvard magna cum laude in 1981, Perlmutter got his Ph.D. from UC Berkeley in 1986. By then the astrophysical bug had bitten him; one possibility that fascinated him was using robotic telescopes to capture fleeting cosmic events "on the fly" -- events such as relatively nearby exploding stars, called supernovae. Perlmutter and his colleagues soon devised ways to guarantee that ever more distant supernovae could be found; with their new search technique, a few nights on the world's best telescopes dependably resulted in many new supernova discoveries.
In the next ten years the Supernova Cosmology Project found dozens of distant type Ia supernovae, ideal for measuring the expansion of the universe. The result was a surprise to scientists everywhere -- the universe is expanding at an accelerating rate. In 1998, Science magazine named the accelerating universe its "Breakthrough of the Year."
Perlmutter emphasizes the importance of group effort. As a violinist who plays in orchestras for pleasure, he finds the same pleasure in scientific collaboration. "I was somebody who had fewer individual heroes and more collective heroes. The idea that people working together could understand the world and that no single one of them by themselves could understand the world, that really captured my imagination."