Robert Karplus - Early Career in Physics

Early Career in Physics

After completing his education Karplus worked at the Institute for Advanced Study in Princeton, where he became interested in the developing, but yet untested, theory of quantum electrodynamics (QED). The magnetic moment of the electron had been determined very precisely by means of a variety of experiments, but the best theoretical calculations of this quantity, based on quantum mechanics, were seriously at variance with the experimental results. There was great interest among physicists in knowing whether or not a calculation based on QED would agree with the experimental results, but because of the ambiguities and complexity of QED, no one had so far been able to do such a calculation. Karplus, in collaboration with Norman Kroll, used QED to calculate the value of the magnetic moment of the electron. This was an extremely difficult calculation, requiring more than a year of intense effort from both men; the agreement between their result and the experimental measurements was the first, dramatic confirmation of QED.

Karplus continued his work at the highest level in theoretical physics for more than 10 years, at Harvard from 1950 to 1954 and then at the University of California, Berkeley, publishing 50 research papers, mostly in QED but also in other areas of physics, including the Hall effect, Van Allen radiation, and cosmic rays. He also thoroughly enjoyed experimental work, investigating the chemistry of Land Camera instant pictures and setting up an experimental germanium purification assembly line for transistors.