Friday, December 10, 2004

Theoretical impotence

Finally, Frank Wilczek's and David Gross's Nobel lectures are available as streaming video: ... (Gross) ... (Wilczek)

Gross was the first one I have watched. I highly recommend you to look at it! David explained how amazing their discovery was in the context of the 1960s.

It was a period of experimental supermacy and theoretical impotence. The experimentalists were making progress all the time while the theoreticians had no clue how to explain the obscure data about strongly interacting physics. Freeman Dyson declared in 1960:
  • The right theory of the strong force won't be found in the next 100 years.
Well, Dyson was only wrong by 87 years, Gross explains. He then sketches the renormalization, screening, anti-screening, quarks, Bjorken scaling, the competition between the S-matrix theory and field theory, the sum rules, the Landau pole and the Soviet claims that field theory was doomed, the pragmatic (calculational) character of American physicists, how quarks suddenly looked real, how the scaling suggested that there can be no interactions, how it seemed that interactions are always stronger at short distances, how they proved it with Coleman for spin below 1 theories, how QCD is beautiful, UV complete, and free of dimensionless parameters, how the asymptotic freedom improves gauge coupling unification, which is also helped by supersymmetry that many of us expect at the LHC, and so forth.

I've also listened to Frank Wilczek's talk - it is complementary in various respects - but someone else should describe it instead of me.


  1. Come on, Lubos, who cares about Gross and Wilczek!? The one Nobel lecture worth watching is going to be Maathais

    Among her qualifying accomplishments are:
    * She's a woman from Africa.
    * She doesn't like to burn fuel. (And she didn't, for lack of opportunity *and* conviction.)
    * She dresses all orange in her finest hour in the civilized world.
    *She's a woman from Africa.

    And you keep talking about this teeny-weeny quarks-stuff-type-of-thing. How boring. ;)) Save a tree, save the day!

    Yours, Mike

  2. Hey Mike!

    Sure, I agree that QCD can't compare with this excellent woman in Africa. I guess that she will now have enough money to burn some fuel. ;-)


  3. Intentional or not, your comments about the 60's seem to mirror the landscape of theoretical physics now. Hopefully we'll score a similar upset!

  4. Dear David,
    nice; this is actually exactly the same idea I wanted to write to the article. ;-)

    Maybe in 2030, a Nobel prize winner will speak in Stockholm, and she will say:

    Back in 2004, we had so many vacua in string theory and it looked so confusing that many famous people, such as Mike Douglas, said that even in the following 100 years, we would not be able to find the right vacuum and we would have to study them just statistically.

    Obviously, a revolution was needed. ;-) And so on...

    All the best

  5. Lubos,

    Check out R. Shankar's stand up comedy. There's a nice bit about how M theory being dual to another theory (you'll have to listen to the mp3 to find out). Just kidding, but it's a pretty good joke.

  6. Lubos, this is Doug. Can you elaborate on what Gross meant when he said something about it's wrong to thing of the Higg's mass?


  7. Hey Doug,

    Gross did not say that there is something wrong with the Higgs mass. Gross said that it is not true that most mass comes from the couplings to the Higgs boson.

    The bare masses of the electron, muon, tau, and quarks come from the coupling with the Higgs boson. You get 511 keV for the electron, 206.8 times more for the muon, 4 MeV for the up quark and 7 MeV for the down quark. These masses of the elementary particles do originate from the Higgs field.

    However, the proton mass (and similarly the neutron mass) is not just a sum of the quark masses. If you sum up the three quark masses, you get roughly 15 MeV. But the mass of the proton is almost 1000 MeV, 60 times more. It's because most of the mass comes from the strong interactions. This mass is m=E/c^2 where E is the total interaction energy between the quarks plus their total kinetic energy - as also explained in Wilczek's talk. The strong interaction between the quarks - which is what Gross, Wilczek, Politzer got their Nobel prize for - contributes 60 times more to the mass of the proton than the coupling of the quarks with the Higgs boson.