4 October 2011
The Nobel Prize in Physics was announced on Tuesday, OCtober 4, “for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.”
One half of the prize went to Saul Perlmutter of the Supernova Cosmology Project, Lawrence Berkeley National Laboratory and University of California, Berkeley. The other half was awarded jointly to Brian P. Schmidt, High-z Supernova Search Team, Australian National University; and Adam G. Riess, High-z Supernova Search Team, Johns Hopkins University and Space Telescope Science Institute.
In 1998, their two research teams raced each other to map the Universe by finding the most distant supernovae, star explosions in space. By establishing the distance to the supernovae and the speed at which they are moving
away from us, scientists hoped to reveal our cosmic fate. They expected to find signs that the expansion of the Universe was slowing down, which would lead to equilibrium between fire and ice. What they found was
the opposite – the expansion was accelerating.
The teams used a particular kind of supernova, called type Ia supernova. It is an explosion of an old compact star that is as heavy as the Sun but as small as the Earth. A single such supernova can emit as much light as a whole galaxy. All in all, the two research teams found over 50 distant supernovae whose light was weaker than expected — this was a sign that the expansion of the Universe was accelerating. The potential pitfalls had been numerous, and the scientists found reassurance in the fact that both groups had reached the same astonishing conclusion.
For almost a century, the Universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago. However, the discovery that this expansion is accelerating is astounding. If the expansion will continue to speed up the Universe will end in ice.
The acceleration is thought to be driven by dark energy, but what that dark energy is remains an enigma – perhaps the greatest in physics today. What is known is that dark energy constitutes about three quarters of the Universe. Therefore the findings of the 2011 Nobel Laureates in Physics have helped to unveil a Universe that to a large extent is unknown to science. And everything is possible again.
All three Nobel laureates have been regular contributors to SPIE symposia. Perlmutter has been an author or co-author on 15 SPIE papers since 1993. His most recent were presented at SPIE Astronomical Instrumentation 2010, covering work on ACCESS, the Absolute Color Calibration Experiment for Standard Stars, a series of rocket-borne sub-orbital missions and ground-based experiments designed to enable improvements in the precision of the astrophysical flux scale.