Norman Kroll

Norman Myles Kroll (6 April 1922, Tulsa, Oklahoma – 8 August 2004, La Jolla, California) was an American theoretical physicist, known for his pioneering work in QED.

Kroll received in 1942 his bachelor's degree from Columbia University after 2 years of study, having studied from 1938 to 1940 at Rice University in Houston. During WW II he did theoretical radar research (magnetron theory), during 1943–1945, at Columbia under the supervision of Willis Lamb and I. I. Rabi. In 1943 Kroll received his master's degree and in 1948 his PhD from Columbia University with Lamb as thesis advisor.

He collaborated with Lamb on their famous paper “On the Self-Energy of a Bound Electron,” which was published in 1949 in the Physical Review and reprinted by Dover Publications in 1959 as part of Selected Papers on Quantum Electrodynamics. Based on Kroll’s thesis work, the paper provided the first theoretical explanation of the Lamb shift in QED and became one of the most important landmarks of the field.

In the academic year 1948–1949 he was a visiting scholar at the Institute for Advanced Study, where he, with Robert Karplus, calculated the QED two-loop contributions for the anomalous magnetic moment of the electron. Kroll was, with Lamb, one of the first (including Victor Weisskopf and his student Bruce French) to calculate the relativistic Lamb shift (after Hans Bethe made a rough, non-relativistic estimate for it). This work was part of the pioneering efforts that led to the QED formalism developed by Richard Feynman, Julian Schwinger, and Sin-Itiro Tomonaga.

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