for discovering that the expansion rate of the universe is accelerating, implying in the simplest interpretation that the energy density of space is non-vanishing even in the absence of any matter and radiation.
Saul Perlmutter, Adam Riess, and Brian Schmidt are awarded the Shaw Prize in Astronomy 2006 in recognition of their leadership roles on the two teams that made the remarkable discovery of an acceleration in the rate of the expansion of the universe. Such an effect had been known theoretically since shortly after Einstein applied his theory of general relativity to cosmology, but the general belief, including Einstein’s own assessment, was that the cosmological constant had no basis in reality. Thus, the 1998 announcement of the acceleration of the universe by the Supernova Cosmology Project and the High-z Supernova Search teams electrified the scientific community. The simplest interpretation, that the vacuum has energy even in the absence of matter and radiation, has profound implications that may revolutionize our understanding of the nature of the physical world and its ultimate fate. It is an achievement that is already taught to schoolchildren.
Einstein replaced Newton’s conception of gravitation as a force with general relativity, which views gravitation as the dynamics of spacetime. In 1917 he applied his theory to the universe as a whole. He made two assumptions: the universe is homogeneous on average and static; and it is closed on itself, a curved volume of space with no boundary. However, Einstein’s equations have no such solutions unless an extra term is inserted that acts as a repulsion to offset the gravitational attraction of matter for itself. Thus were born both modern cosmology and the notion of a cosmological constant, Lambda.
In 1929 Hubble found that the universe is expanding, a feature that Friedmann and Lemaître had shown were necessary consequences of Einstein’s equations if Lambda were zero. There are then three models depending on whether the geometry of space is closed, Euclidean, or open. All three models are characterized by a deceleration in the expansion from a big bang.
Saul Perlmutter, born 1959 is presently a Professor of Physics at the University of California, Berkeley, and Senior Scientist at Lawrence Berkeley National Laboratory. He joined the University of California Berkeley Physics Department in 2004. He is also an astrophysicist at Lawrence Berkeley National Laboratory and leader of the international Supernova Cosmology Project, which first announced the results in 1998 indicating that the universe will last forever, with its expansion ever accelerating.
He graduated from Harvard magna cum laude in 1981, and received his PhD from the University of California, Berkeley in 1986. He was elected a member of the National Academy of Sciences of the USA in 2002.
Adam Riess, born 1969 is an astronomer at the Space Telescope Science Institute and a Professor at Johns Hopkins University in Baltimore, USA. Between 1996 and 1999 Professor Riess was a Miller Fellow at the University of California, Berkeley.
Professor Riess received his BS in Physics from the Massachusetts Institute of Technology in 1992 where he was inducted into the Phi Beta Kappa Society. He received his PhD from Harvard University in 1996.
Brian Schmidt, born 1967 is a Federation Fellow at the Australian National University’s Mount Stromlo Observatory, Canberra. Professor Schmidt received undergraduate degrees in Physics and Astronomy from the University of Arizona in 1989, and his Master’s degree (1992) and PhD (1993) in Astronomy from Harvard University.
