Tuesday, December 8, 2015

A comparative appreciation of P.W. Anderson and Linus Pauling

Andrew Zangwill contacted me because he is working on scientific biography of Phil Anderson. I think this is overdue. I would argue that Phil is the greatest theoretical physicist of the second half of the twentieth century. I would argue this on similar grounds to why I think Linus Pauling was the greatest theoretical chemist of the first half of the twentieth century. Crucially, their scientific legacies have extended far beyond condensed matter physics and chemistry, respectively.

Specifically, Pauling did not just make essential contributions to our understanding of chemical bonding, x-ray crystallography, and quantum chemistry. His impact went far beyond chemistry. Francis Crick said Pauling was the "father of molecular biology." He proposed and elucidated alpha helices and beta sheets in proteins. Furthermore, he began the whole field of molecular medicine, by showing the molecular basis of a specific disease, sickle cell anemia.

Phil Anderson has made incredibly diverse and valuable contributions to condensed matter physics (anti-ferromagnetism, localisation, weak localisation, magnetic impurities in metals, Kondo problem, poor mans scaling, superfluid 3He, spin liquids, RVB theory of superconductivity... ).
I can think of three significant and profound influences of Phil beyond condensed matter physics.

Codifying and elucidating the concept of emergence (and the limitations of reductionism) in all of science, in More is Different in 1972.

Laying ground work for the Higgs boson in 1963 by connecting spontaneous gauge symmetry breaking and mass. 

Elucidating spin glasses in a way that was key to John Hopfield's development of a particular neural network and to the notion of a "rugged landscape", relevant in protein folding and evolution. Anderson described these connections nicely in two pages in Physics Today in 1990.

Are there other examples?

Who do you think is the greatest theoretical physicist of the second half of the twentieth century?
[n.b. If you are thinking Feynman, he did path integrals and QED before 1950].


  1. Localization (Absence of Diffusion in Certain Random Lattices, 1958)

  2. Replies
    1. Guatam,

      Thanks for the suggestion.


      I think Wilson vs. Anderson is an interesting question. Wilson is particularly impressive because his contributions spanned condensed matter and field theory. But I don't think he has much influence outside physics beyond Feigenbaum using RG ideas in chaos theory.

      The other thing that is interesting is that Anderson actually applied scaling to Kondo before Wilson.

  3. Walter Kohn should probably get a mention.

  4. I think that P.W. Anderson was the greatest theorical physicist in the second half XX century, for many reasons. But, your work in the gauge field theory is one of the most beautiful in physics. About Superconductivity is important talk in Lev Gor'kov, almost forgotten every time.