The 2011 Nobel Prize in Physics

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.

This year’s Nobel in Physics goes to Saul Perlmutter, Brian Schmidt, and Adam Riess for their discovery that the expansion of the Universe is accelerating, not decelerating as expected. This result came from an examination of distant supernova, and has been confirmed by an examination of the cosmic microwave background and the dynamics of galaxy clusters.

Dr. Perlmutter led a team studying distant type Ia supernova occurring in binary star systems in which a white dwarf accretes matter from the evolving companion. As the white dwarf’s mass grows, it becomes unstable, and eventually destroys itself in a huge blaze of energy which can be seen across the Universe. These explosions are amazingly uniform and consistent in energy, which enable astronomers to use them as “standard candles”, or objects of known absolute brightness. By measuring the observed peak brightness, the distance to the supernova can be computed.

Drs. Schmidt and Riess started a second search for high-z, or distant, supernova a few years later. Both teams came to similar but astonishing conclusions; the Universe’s expansion is not decelerating, but rather is speeding up over time.

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