2 Japanese, American win physics Nobel

An American and two Japanese physicists on Tuesday won the Nobel Prize in Physics for their work exploring the hidden symmetries among elementary particles that are the deepest constituents of nature.

Yoichiro Nambu, 87, of the University of Chicago's Enrico Fermi Institute, will receive half of the 10 million krona prize (about $1.4 million) awarded by the Royal Swedish Academy of Sciences.

Makoto Kobayashi, 64, of the High Energy Accelerator Research Organization in Tsukuba, Japan, and Toshihide Maskawa, 68, of the Yukawa Institute for Theoretical Physics at Kyoto University, will each receive a quarter of the prize.

Ever since Galileo, physicists have been guided in their quest for the ultimate laws of nature by the search for symmetries, or properties of nature that appear the same under different circumstances. "It's the lamppost we search under," said Michael Turner, an astrophysicist at of the University of Chicago.

One example of an obvious symmetry is a snowflake, which looks the same when you rotate it through one-sixth of a turn. Another is Einstein's theory of relativity, which says the laws of physics are the same no matter what speed. However, in the 1960s, Nambu, inspired by studies of superconductivity, suggested that some symmetries in the laws of elementary particle physics might be hidden, or "broken" in actual practice. "You have to look for symmetries even when you can't see them," Turner said.

The principle of symmetry breaking is now embedded in all of modern particle physics. The $8 billion Large Hadron Collider, a giant particle accelerator soon to go into operation outside Geneva, was designed largely to find a particle known as the Higgs boson, which is theorized to be responsible for breaking the symmetry between electromagnetism and the so-called weak nuclear force, imparting mass to many particles that in theory are massless.

In 1972, Kobayashi and Maskawa, extending work by the Italian physicist Nicola Cabibbo, showed that if there were three generations of the elementary particles called quarks, the constituents of protons and neutrons, the principle of symmetry breaking would explain a puzzling asymmetry known as CP violation.

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