DAVID PARKER / SCIENCE PHOTO LIBRARY DAVID PARKER / SCIENCE PHOTO LIBRARY
Saul Perlmutter. Portrait of the American cosmo- logist Saul Perlmutter. Perlmutter is head of the Supernova Cosmology Project (SCP) at the Lawrence Berkeley Laboratory, part of the University of California, USA. The SCP studies "type Ia" super- novae, a type of explosive star death which all have the same intrinsic brightness, allowing their distances to be accurately measured. By studying the light spectra of these explosions, researchers at the SCP determined how fast the universe was expanding when the stars exploded. They found that the universe is expanding at an accelerating rate, implying it will expand forever, rather than being slowed by gravity. Photographed in 1999.
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