Wednesday, April 24, 2013

Did Fritz London surpass Einstein and Bohr?

I learned today of two impressive endorsements of Fritz London as a great theoretical physicist.

First, after John Bardeen got his second Nobel Prize he used the money to endow the Fritz London lectures at Duke University.

Second, in 2005 Phil Anderson wrote an essay in Nature, Thinking big which lauded London for having the vision that quantum theory was correct on all length scales, including the macroscopic, as manifested in superconductivity and superfluidity. Furthermore, Anderson argues this allows a "common sense" understanding of the quantum measurement problem.

London's vision is contrasted with that of Bohr and Einstein, of whom the "thoughtful curmudgeon" says
In reading about these [Einstein-Bohr] debates I have the sensation of being a small boy who spots not one, but two undressed emperors. Niels Bohr’s ‘complementarity principle’ — that there are two incompatible but equally correct ways of looking at things — was merely a way of using his prestige to promulgate a dubious philosophical view that would keep physicists working with the wonderful apparatus of quantum theory. 
Albert Einstein comes off a little better because he at least saw that what Bohr had to say was philosophically nonsense. But Einstein’s greatest mistake was that he assumed that Bohr was right — that there is no alternative to complementarity and therefore that quantum mechanics must be wrong. This was a far greater mistake, as we now know, than the cosmological constant.
I first learnt of these two endorsements in a beautiful essay by David Pines, Emergent behavior in quantum matter.

Aside: London's theory of the van der Waals interaction may have been the first case of deriving an effective low-energy Hamiltonian by integrating out high energy states, as discussed in the last point of this post.

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