Nobel for symmetry breaking

Great news for particle physics –  the 2008 Nobel Prize in Physics has been awarded for hidden gauge symmetry.

This year’s prize has been awarded to three particle theorists – one half to Yoichiro Nambu“for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics”, and the other half to Makoto Kobayashi and Toshihide Maskawa “for the discovery of the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature”

While I was betting on a prize for neutrino oscillation (experimental), most would agree that the Nambu prize is long overdue. He was the first to introduce the concept of spontaneous symmetry breaking to particle physics, having studied the phenomenon in superconductivity. The idea caught hold rapidly and was a seminal step in the construction of the Standard Model of particle physics (for example, symmetry breaking is an integral part of the theory of the electro-weak interaction, and the process by which particles acquire mass via the Higgs field is thought to be an example of symmetry breaking).

There’s more: among theoreticians, Nambu is most revered for his discovery of the gauge theory of the strong interaction  – in other words as the grandfather of quantum chromodynamics. And if that weren’t enough, he is also a godfather of string theory, so some may see this prize as a nod towards string theory.

Nambu: pioneer of gauge symmetry, QCD and string theory

Spontaneous symmetry breaking : symmetry is broken as the ball rolls down the hill

I know less about the others, but Kobayashi and Maskawa developed the mechanism of CP violation in the weak force, and how CP violation is reflected in the interactions of quarks – this work led to the prediction of  three generations of quarks (the last of the 3rd generation of quarks was found in the 1990s).  CP violation is crucial to our understanding of the asymmetry of matter and antimatter, and was experimentally demonstrated in some famous k -meson experiments in the 1960s (more recent experiments at the BaBar detector at Stanford and the Belle detector at KEK in Japan have also demonstrated CP violation). Next year, matter/antimatter asymmetry and CP violation and will be examined in further detail at the LHCb experiment.

You can find more details and the official announcement on the Nobel site here.

All in all, a good day for particle physics, as spontaneous symmetry breaking is a crucial component of the modern theory of elementary particles. I do have my reservations about Nobel prizes in general, but I’ll leave that discussion for another day..


A couple of people hinted darkly at political timing over lunch – is it a coincidence that the prize should be awarded to particle physics in this year, the year of the LHC?

I think it is, and even if not so what. The prize is decades overdue, in all three cases. The importance of hidden gauge symmetry in particle physics may not be as obvious as the latest measurements of the Cosmic Microwave Background (say), but it is a vital piece of our understanding of the subatomic world. Plus, the relevant experiments have been done decades ago.


For a more technical discussion of the issues above, see today’s postings on blogs such as Symmetry Factor and Not Even Wrong.  An important point being made is that the third (and original) physicist of the Cabibbo-Kobayashi-Maskawa matrix was overlooked – Cabibbo is yet another victim of the silly Nobel rule that the prize can only be awarded to three. This is also true of Goldstone, a gauge theorist who even has a famous particle named after him- in an ideal world one Nobel prize should go to Nambu and Goldstone, and another to C,K and W. There is a good discussion of this on T. Dorigo’s blog  A Quantum Diaries Survivor

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