Three scientists who probed the mysteries of particle physics have been awarded the Nobel Prize in physics, the Royal Swedish Academy of Sciences announced today. The winners are Yoichiro Nambu, a Tokyo-born American citizen, and Makoto Kobayashi and Toshihide Maskawa of Japan.
Nambu identified a mechanism called spontaneous broken symmetry in subatomic physics. Kobayashi and Maskawa work predicted the existence of three families of elementary particles known as quarks. According to the Standard Model of particle physics, quarks are the sub-units of protons and neutrons, which together make up the nuclei of atoms [BBC News].
"Spontaneous broken symmetry conceals nature's order under an apparently jumbled surface," the academy said in its citation. "Nambu's theories permeate the standard model of elementary particle physics. The model unifies the smallest building blocks of all matter and three of nature's four forces in one single theory." Kobayashi and Maskawa "explained broken symmetry within the framework of the standard model but required that the model be extended to three families of quarks" [AP].
Nambu proposed his theory of spontaneous broken symmetry in 1960, while Kobayashi and Maskawa studied different types of broken symmetries in the 1970s. The hypothetical quarks that their model predicted have recently appeared in physics experiments, the Nobel Foundation noted.
"As late as 2001, the two particle detectors BaBar at Stanford ... and Belle at Tsukuba, Japan, both detected broken symmetries independently of each other. The results were exactly as Kobayashi and Maskawa had predicted almost three decades earlier," the citation said [AP].
The Nobel Foundation notes that we owe our existence to an example of broken symmetry:
It must have occurred immediately after the Big Bang some 14 billion years ago when as much antimatter as matter was created. The meeting between the two is fatal for both; they annihilate each other and all that is left is radiation. Evidently, however, matter won against antimatter, otherwise we would not be here. But we are here, and just a tiny deviation from perfect symmetry seems to have been enough – one extra particle of matter for every ten billion particles of antimatter was enough to make our world survive [Nobel Foundation, pdf].
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