Dark-energy discoverers share cosmology prize

Saul Perlmutter, Brian Schmidt, and their respective teams, the Supernova Cosmology Project and the High-z Supernova Search Team, are the recipients of the 2007 Gruber Cosmology Prize “for their discovery that the expansion of the Universe is currently accelerating.” The prize, being presented this month at a ceremony at the University of Cambridge, will be shared by the two team leaders and the 51 coauthors of the key papers.

Both teams reported in 1998 that the expansion of the universe is not slowing, as was generally expected, but was instead increasing (see the article by Perlmutter in Physics Today April 2003, page 53 ). Their conclusions were based on studies of type Ia supernovae—standard candles with which the teams could accurately determine distances billions of light-years away. “An accelerating universe was a crazy result that was hard to accept,” wrote the Peter and Patricia Gruber Foundation. “The discovery of the accelerated expansion has radically changed our perception of cosmic evolution.” To account for the acceleration, astronomers have posited the existence of an expansive force dubbed dark energy, now thought to account for about three-quarters of the mass-energy in the universe.

Perlmutter is an astrophysicist at Lawrence Berkeley National Laboratory and a professor of physics at the University of California, Berkeley. Schmidt is an Australian Research Council Federation fellow at the Australian National University’s Mount Stromlo Observatory.