Two astronomers who received their Ph.D.s from Harvard’s Graduate School of Arts and Sciences were named today as among the three winners of the 2011 Nobel Prize in physics for their discovery that the universe is expanding at an ever-accelerating rate — a discovery that shook cosmology “at its foundations,” said the Royal Swedish Academy of Sciences in announcing the prize.

Adam Riess, Ph.D. ’96, of the Space Telescope Science Institute and Johns Hopkins University, and Brian Schmidt, Ph.D. ’93, of the Australian National University, share the prize with Saul Perlmutter of the Lawrence Berkeley National Laboratory and the University of California, Berkeley.

At Harvard, Riess and Schmidt shared a mentor and Ph.D. adviser in Robert P. Kirshner, himself an expert on supernovae, and the author of the popular book “The Extravagant Universe: Exploding Stars, Dark Energy, and the Accelerating Cosmos.”

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