By Mcallister Hull

For nearly fifty year, Gregory Breit was a leading figure in the development of physics in the twentieth century. John Wheeler in Some Men and Moments in Nuclear Physics wrote, ''Insufficiently appreciated in the 1930's, he is today the most unappreciated physicist in America." This was written in 1979, when Gregory was in physical decline, and he probably never saw it, but if public recognition was slight (but by no means absent), he was appreciated very well (in spite of a difficult personality) by his students, collaborators, and colleagues. The range of his interests and duration of his active career made this cadre a large one.

Trained as an electrical engineer, Breit did his early work in radio, including the definition of the characteristics of early tubes and finite coils. The most important of this work, with Merle Tuve, was the use of radio to demonstrate the existence of the postulated ionosphere by receiving return signals of a pulsed radio beam sent from the earth's surface. Ranging with a pulsed signal is, of course, the principle of radar. He also inspired and worked with the production of high voltages to accelerate charged particles (protons) to use as probes of the nucleus—the first manmade probes in the United States (Cockroft and Walton at Cambridge, England, had a beam of protons and deuterons