Tuesday, October 04, 2011

Physics Nobel Prize

Three American scientists were awarded the 2011 Nobel Prize for physics for “the discovery of the accelerating expansion of the Universe through observations of distant supernovae.

The Nobel Prize Committee said that half of the award was given to Saul Perlmutter currently at Lawrence Berkeley National Laboratory, while the other half was split between Brian Schmidt at the Australian National University and Adam Riess at Johns Hopkins University.

In 1997 through 1998 the two research teams examined the redshifts of distant supernovas to measure the expansion of the universe. They both independently published findings in 1998 announcing the unexpected conclusion that the universe appears to be accelerating as it expands. The discovery came as a complete surprise to the field, and finding out its cause is one of the biggest mysteries in cosmology.

“Not only do we not know what dark energy might be, that would be making the universe expand faster and faster, we don't even know whether really the answer will turn out to be a new energy in the universe,” Pearlmutter said in an interview with Nobel Media following the announcement. “It's possible that we've just discovered an extra wrinkle in Einstein's Theory of Relativity, and that that would be the real final result. But at this point, the job is really back in our court again as observers, and we have to come up with more data that will help narrow in on what the answer is.”

Further investigation showed that this mysterious force, often dubbed “dark energy” makes up about three quarters of the known universe. Dark matter makes up about 20 percent of the universe, leaving only 5 percent of the universe visible by normal means.

“I think that the idea of the accelerating universe, indicating that there was some other big thing in the universe, other than things that have normal gravity, meant that a lot of the problems that existed in cosmology back in 1998 were suddenly solved if this stuff existed,” Schmidt said in an interview with Nobel Media. “So there was a lot of people, especially theorists, who wanted the universe to be geometrically flat, which means it had to have a lot of stuff in it that we just didn't know was there. And this stuff solved that problem. It gave the extra matter in the universe that needed to be flat.”

Many have compared dark energy to Einstein’s defunct “cosmological constant” his original general theory of relativity which he used to explain the existing belief of a static universe. In 1999, physicist Michael Turner, coined the term “dark energy” in a paper published in Physical Review D.

“We actually did not have to propose [dark energy], seeing that there was, I would say, off-the-shelf and ready, a model from Albert Einstein, something he referred to as the cosmological constant, which would neatly do the trick. And so all we did was to say that that seemed like at that point the simplest hypothesis,” Reiss said in an interview with Nobel Media.

This year has seen the Nobel Prize Committee make a couple of gaffes when awarding the prizes. It turns out that they didn't have Pearlmutter's home phone number, and he inadvertently learned he won the prize when a reporter from Sweden called him. On Monday, the committee awarded part of its medicine prize to Dr. Ralph Steinman who passed away days earlier.

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