U.S. theorist, 2 Japanese win Nobel in physics

A Japanese-American theorist whose work helped explain how the cosmos came into being and two Japanese theorists who predicted the existence of a family of exotic particles called quarks will share the 2008 Nobel Prize in Physics, the Swedish Nobel Foundation said Tuesday.

All three studied a curious but essential phenomenon known as broken symmetry, which helps to explain the behavior of matter on the smallest scale, where the everyday laws of physics seemingly break down or are ignored.

Yoichiro Nambu, 87, a Tokyo-born physicist at the University of Chicago's Enrico Fermi Institute, will receive half the $1.4 million prize for his mathematical description of "spontaneous broken symmetry," which played a major role in development of the Standard Model of particle physics, which integrates elementary particles and the strong, weak and electromagnetic forces of nature.

Makoto Kobayashi, 64, a researcher at the High Energy Accelerator Research Organization, or KEK, in Tsukuba, Japan, and Toshihide Maskawa, 68, of Kyoto University's Yukawa Institute for Theoretical Physics, will share the other half of the award for their explanation of why the breakdown of elementary particles called kaons and B-mesons is not symmetrical, as scientists had once thought it should be.

Nambu, who moved to the United States in 1952, said he was surprised and honored when he received news of the award Tuesday. "I didn't expect it. I've been told for many years that I was on the list" to receive the award, he told The Associated Press. "I had almost given up." He became a U.S. citizen in 1970.

At a news conference in Tsukuba, Kobayashi said he also was not expecting the award. "I've only been pursuing my interest. ... It's an honor to receive the prize for my work from long ago. I wrote that paper more than 30 years ago."

At a separate news conference in Kyoto, however, Maskawa said he saw it coming.

"There is a pattern to how the Nobel Prize is awarded," he said. "I did not think I would get the award up until last year, but I predicted it pretty much this year."

He also seemed less than impressed with the award. "The Nobel Prize is a rather mundane thing," he said. "I was happier when our theories were acknowledged around 2002."

Three fundamental types of symmetry play a major role in physics: mirror, time and charge parity. Mirror symmetry says that particles in a mirror universe behave exactly as those in this one, so an observer cannot tell which universe he is watching. The letter "A," as an example, looks the same in the mirror and the real worlds.

Time symmetry means that physical processes look the same whether time is going forward or backward, such as a movie of colliding billiard balls. Charge parity means that particles in the universe of antimatter — in which particles have the same properties as in conventional matter but charges are reversed — should behave exactly as particles in the matter universe.

But if charge parity truly applied, the universe would not exist. If matter and antimatter had been created in equal quantities during the big bang, all matter and its antimatter counterparts would eventually have come into contact and exploded, leaving behind only radiation.

But for every 10 billion antimatter particles created when the cosmos was formed, 10 billion plus one matter particles were formed. This slight excess allowed the universe we know to remain intact. Nambu's theories explained how this spontaneous broken symmetry could occur.

Physicists think that a never-before-detected particle called the Higgs boson may be responsible for this spontaneous broken symmetry. The $8 billion Large Hadron Collider at the European Organization for Nuclear Research, or CERN, was built to detect the Higgs particle or particles. Scientists will be looking for the Higgs particle when they restart the collider in spring 2009.

Symmetry is also broken in the breakdown of certain elementary particles, such as the kaon. Nobel laureates James Cronin and Val Fitch discovered in the 1960s that the radioactive decay of kaons produced a minute excess of matter over antimatter.

Kobayashi and Maskawa provided a theoretical explanation for this phenomenon, predicting the existence of six new elementary particles: two charmed quarks, top and bottom quarks and two strange quarks. These quarks were discovered experimentally between 1974 and 1994.

They also predicted a similar symmetry breakdown in the decay of particles called B-mesons. The Stanford Linear Accelerator in California and the KEK accelerator in Japan produced large quantities of B-mesons for study and confirmed the theoretical prediction.

Information from The Associated Press and The Washington Post is included in this report.