Willis Lamb, RIP

Willis Lamb, a major contributor to atomic physics and laser theory and recipient, (split with Polykarp Kusch), of the 1955 Nobel Prize in Physics for measurements of hydrogen fine structure (including his eponymous shift) died today from complications of a gallbladder disorder. He was ninety-four years old.

Lamb's career arc is quite interesting. He performed his PhD work under the direction of Robert Oppenheimer performing neutron scattering experiments to probe the electrical properties of the atomic nucleus. He went on to become a pioneer of microwave spectroscopy; his measurements (largely in collaboration with Robert Retherford) of the electronic fine structure of hydrogen provided an early test for quantum electrodynamics.

Note the short length, relaxed language, and fast turnaround at Physical Review sixty years ago. Some things have not changed for the better!

Later in his career he shifted somewhat to being a theorist, becoming a major contributor to the theory of lasers, including the now ubiquitous ring laser gyroscope. In his many later years he also became in many ways the official curmudgeon of quantum optics and the University of Arizona's Optical Sciences Center, infamously offering "licenses" for use of the term "photon". Most of his theoretical work was done in a semiclassical formalism; some of it would almost seem to imply that he was never quite comfortable with quantization of the light field and sought to avoid it if possible, but his 1994 essay in Applied Physics B, "Anti-Photon", is right on the money and worthwhile reading for anyone interested in fundamental physics. "Photon" is not a synonym for "light" or "radiation", the electromagnetic field cannot be considered to be like bowling balls or an atom beam, and one certainly should not be able to claim with a straight face, especially after even a few hours studying quantum optics, that lasers "produce vast numbers of particles of exactly the same energy and wavelength."

Lamb is survived by his wife Elsie, his brother Perry, and many former students and collaborators. An official obituary can be found on the University of Arizona website.