U.S. Scientists Awarded Nobel Prize In Physics
October 4, 2011

U.S. Scientists Awarded Nobel Prize In Physics

Three scientists were awarded the Nobel Prize in physics on Tuesday for showing that the expansion of the universe is constantly accelerating.

Physicists believed for decades that the expansion of the universe was getting slower, but U.S. scientists Saul Perlmutter, Brian Schmidt and Adam Riess determined it was just the opposite.

The three men worked on separate research teams in the 1990s and found that light from over 50 distant exploding stars was weaker than they expected.  This observation meant that galaxies had to be racing away from each other at increasing speed.

Riess, an astronomer at the Space Telescope Science Institute (STScI), thanked the Nobel Foundation for the award and said: "My involvement in the discovery of the accelerating universe and its implications for the presence of dark energy has been an incredibly exciting adventure. I have also been fortunate to work with tremendous colleagues and powerful facilities. I am deeply honored that this work has been recognized."

Riess and both Perlmutter and Schmidt were also awarded the Peter Gruber Foundation's 2007 Cosmology Prize for their discovery in 1998.

Riess led the study for the High-z Supernova Search Team, which resulted in the 1998 discovery that the universe's expansion is accelerating.

"We originally set out to use a special kind of exploding star called 'supernovae' to measure how fast the universe was expanding in the past and to compare it to how fast it is expanding now," Riess said in a Nobel press release. "We anticipated finding that gravity had slowed the rate of expansion over time. But that's not what we found."

Riess and his team are trying to measure dark energy's two most fundamental properties, which are how stable it is and how it has changed with the evolving universe.

The Nobel prize winners will receive a medal and diploma and will share a cash award of $1.49 million.


Image Caption: The brilliant, blue glow of young stars trace the graceful spiral arms of galaxy NGC 5584 in this Hubble Space Telescope image. Thin, dark dust lanes appear to be flowing from the yellowish core, where older stars reside. The reddish dots sprinkled throughout the image are largely background galaxies. Credit: NASA, ESA, A. Riess (STScI/JHU), L. Macri (Texas A&M University), and Hubble Heritage Team (STScI/AURA)


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