Tuesday, October 07, 2008

Nobel Prize in physics 2008

I've found the awarding of physics Nobel prizes in the last decade or two to be, well, erratic. Probably it was always erratic, but this was not apparent to me as a student, and the particulars of prizes even further past are lost to the mists of time.

Once again, I'm not sure I understand today's selection of Nambu together with Kobayashi and Maskawa. All are deserving theoreticians. K-M generalized the flavor mixing matrix of Cabibbo to 3 flavors and thereby introduced the likely origin of (thus far observed) CP violation.

But what is the justification of the Nambu prize? If it is for spontaneous symmetry breaking shouldn't people like Goldstone, Higgs, Englert, Brout, etc. also share the prize? The citation says

...for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics.

If by mechanism they mean the general phenomena of spontaneous symmetry breaking then surely others deserve credit as well. If by mechanism they mean the actual dynamics, then I can only conclude they are giving the prize for the Nambu-Jona-Lasinio model? (Which is clearly not deserving of the prize!)

I think a more appropriate choice would have been Cabibbo-Kobayashi-Maskawa (Cabbibo is still alive) and Nambu-Goldstone + other.

Note added: I take back my comment about Cabibbo. The prize citation for KM is really for CP violation, and Cabibbo played no role in that. Regarding Nambu, the citation focuses on his being the first to discuss spontaneous symmetry breaking in a field theoretic context (not exactly Nobel worthy, in my view), and being the first to guess that the strong interactions exhibit spontaneous symmetry breaking, making an analogy with a conventional superconductor. This analogy is fleshed out in a talk given at Purdue in 1960, one year before Goldstone's scalar model which explicitly realizes what has now become known as a Nambu-Goldstone boson. Probably Nambu was the first person to deeply understand that the strong interaction (QCD) ground state spontaneously breaks axial symmetries -- I suppose that is by itself worthy of the prize.

See this Nobel committee scientific report for more details. Thanks to reader MFA for the pointer!


Anonymous said...


Actually, the Nobel citation does a decent job of explaining reasons for giving Nambu the prize:

Nambu had discovered spontaneous symmetry breaking in a field theoretic formulation.

and especially
The really bold assumption that Nambu now made in 1960 [44] was that spontaneous symmetry breaking could also exist in a quantum field theory for elementary particles.

Note that [44] was before Goldstone and others---he was certainly the first on the subject (in QFT/particle theory). It is true that the original NJL is by itself not that great, but to be the first to propose relevance of SSB in particle physics is certainly very impressive. Perhaps Higgs and Goldstone at a later date. Sometimes one prize is not enough. Kinda like GSW '79 before 't Hooft and Veltman '99---without the latter's work, nobody would have paid attention (and nobody did!) to the GSW work.

Many of the older generation physicists I knew thought Nambu deserved it for SSB in QFT and particle physics for work cited and uncited.


Steve Hsu said...

I'm not questioning whether Nambu deserves the prize. But this way of separating his work out based on a talk seems strange to me.

[44] Y. Nambu, “A ‘Superconductor’ Model of Elementary Particles and its Consequences”,
Talk given at a conference at Purdue (1960).

Anonymous said...

It's like they decided national origin was a more important dividing line than subject matter.

Jeff said...

I suppose this is the closest that the BaBar/Belle experiments will come to receiving a Nobel.

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