Page last updated at 13:54 GMT, Tuesday, 7 October 2008 14:54 UK

Cosmic imperfections celebrated

By Jonathan Amos
Science reporter, BBC News

Artist's impression of quarks (SPL)
The protons and neutrons in atoms are made up of quarks

The Nobel Prize for physics this year lauds three individuals who described tiny - but hugely significant - flaws in the fabric of the Universe.

Yoichiro Nambu, Makoto Kobayashi and Toshihide Maskawa have all provided new insights into the nature of matter.

Nambu described a mechanism called spontaneous broken symmetry in sub-atomic physics.

The work of Kobayashi and Maskawa predicted the existence of three families of particles known as quarks.

According to the Standard Model in particle physics - which ties together the smallest known building blocks of matter and three of nature's four fundamental forces - quarks are the elementary sub-units of protons and neutrons, which together make up the nuclei of atoms.

The new laureates' investigations explain anomalies in the laws of physics.

'Long overdue'

According to the Royal Swedish Academy of Sciences, "spontaneous broken symmetry is said to conceal nature's order under an apparently jumbled surface".

One analogy is to consider a pencil balancing on its point that then suddenly falls over. Prior to falling, the pencil is in perfect symmetry and has no preferred direction in which to topple; but in moving to the lower energy position of resting lengthways on the surface, the pencil suddenly defines a direction and the symmetry is broken.

Nambu is said to have formulated a mathematical description for this phenomenon in particle physics. The work is highly relevant in relation to upcoming experiments on the Large Hadron Collider (LHC), the recently completed giant accelerator at Cern on the Swiss-French border.

The LHC will search for an explanation for why the Universe has mass - with the leading candidate being the so-called Higgs field.

At the extremely high energies that existed in the very early Universe, symmetries would have existed that were then suddenly broken as the cosmos cooled and expanded. Theory suggests mass resulted when the Higgs field lost its symmetry.

Professor Sir Chris Llewellyn Smith, who was director general at Cern in the 1990s, said Nobel recognition for Nambu was long overdue.

"Hidden symmetries allow simple, economical laws to give rise to very diverse, apparently unrelated, phenomena," he commented.

"They play a key role in the unification of different forces in the successful Standard Model of particle physics."

Makoto Kobayashi, left, smiles upon being congratulated by Japanese Prime Minister Taro Aso on his mobile
Makoto Kobayashi (L) takes a call on his mobile from Japan's Prime Minister

Broken symmetry has become powerful concept in particle physics in recent decades.

Prior to the 1950s and 60s, it was thought the laws of physics would be invariant - they would look and perform the same in mirrored spatial directions; in forward and reverse time; and between particles and their opposites, anti-particles.

Toshihide Maskawa
Toshihide Maskawa speaks at a press conference in Kyoto

Observations of decaying sub-atomic particles in accelerators, however, demonstrated that these symmetric effects were being broken; and one of the most important is a spatial and time inconsistency which has become known as CP violation.

Jim Stirling, a professor of particle physics at Cambridge University, explained: "When we wish to build a theory in which broken symmetry is incorporated then we have to add to the theory some aspect, some property of the theory, that distinguishes between particles and anti-particles; and the work of Kobayashi and Maskawa was based on trying to understand the CP violation that was observed; and they postulated there should be more particles than were known at the time.

"They suggested that in addition to the two generations of quarks known at the time, there should be a third generation; and this was before the third generation was discovered."

Observations subsequently confirmed the Kobayashi and Maskawa predictions.

Professor Nambu, 87, from the University of Chicago, is a US citizen but was born in Japan.

Professor Kobayashi, 64, works at the KEK Laboratory, Tsukuba, Japan; while Professor Toshihide Maskawa, 68, is affiliated to the University of Kyoto, Japan.

The Nobel Prizes - which also cover chemistry, medicine, literature, peace and economics (more properly called the Sveriges Riksbank Prize) - are valued at 10m Swedish Kronor (800,000; $1.4m).

Nambu will receive 5m Kronor; Kobayashi and Maskawa will share the other half.

Laureates also receive a medal and a diploma.

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