Breit, Gregory

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(b. Nikolayev, Russia, 14 July 1899; d. Salem, Oregon, 11 September 1981),


Breit was one of the most prolific members of the U.S. physics community for nearly fifty years. Equally active in experimental and theoretical physics, he left his mark in geophysics (upper-air studies), radio, ballistic, and accelerator technology, experimental nuclear physics, and, above all, in nuclear theory—with his seminal contributions to nucleon-nucleon scattering and nuclear reactions. His wartime contributions included neutron studies, ship degaussing, the proximity fuse, and various ordnance problems. Reflecting the breadth of his interests, and despite a difficult personality, he left a large school of appreciative students, colleagues, and collaborators—the “Breit group,” as it was called—attested to by the many notable speakers at a symposium in his honor at Yale in 1968.

Yet Breit was hardly known at all in the early twenty-first century. As emphasized by John Wheeler, one of his close colleagues, “Anyone in the United States who before World War II contributed more importantly to more fields of physics than Gregory Breit would be difficult to name.” However, oddly enough, continues Wheeler, “Insufficiently appreciated in the 1930s, [Breit] is today the most unappreciated physicist in America” (1979, p. 234). Part of this lack of recognition can probably be blamed on Breit’s legendary irascibility. This in spite of Breit’s devotion to the development of his students, a trait McAllister Hull treats as “equally legendary” (p. 34).

Background. Breit’s parents, Alfred and Alexandra Smirnova Breit Schneider, operated a textbook business in Nikolayev, some 100 kilometers northeast of Odessa on the Black Sea. When Alexandra died in 1911, the business was sold, and the next year Alfred emigrated to the United States, leaving Gregory and his sister Lubov in the charge of a governess. In 1915, Alfred insisted that his children follow him to the United States, and with their governess they traveled by train to Arkhangelsk, and thence by steamer to New York. They joined their father, Alfred Breit, having dropped “Schneider” from the family name, in Baltimore where he had settled.

In addition to his sister Lubov, Gregory had an older brother, Leo, who had avoided recruitment in the tsar’s army by fleeing through Turkey; he, too, wound up in Maryland where he practiced medicine—still sought by the tsar’s agents as a deserter. Gregory, by contrast, approached Russian recruiters in 1918, eager for service in the Russian army. Turned down on physical grounds, he continued his higher education, begun at the School of Emperor Alexander in Nikolayev, by enrolling at Johns Hopkins University in Baltimore. There he earned his AB in 1918, the MA in 1920, and the PhD in 1921, all three degrees in electrical engineering. His dissertation, under the advice of Joseph Sweetman Ames, was on the distributed capacity of inductive coils. This work, with both calculations and measurements, Breit carried out while he was an apprentice in the Radio Section of the Bureau of Standards. A man of great reputation, the motto of “Joe Ames” was that “no matter what it is, everybody who is anybody at Hopkins goes to work on something that deeply interests him”—an admonition that suited Gregory, only twenty-two in 1921, to a tee (Wheeler, 1979, p. 219).

Career. With his doctorate in hand, Gregory Breit served a postdoctoral stint as a National Research Council fellow at the University of Leiden (1921–1922). There, in his own words, he “was exposed to the influence of Ehrenfest in theory and of Kamerlingh Onnes in experiment.” Kamerlingh Onnes’s influence on his career would prove to have “been salutory,” and “being with Ehrenfest was also an unforgettable experience” (Bromley et al, 1970, p. 192). He held a subsequent fellowship at Harvard University (1922–1923), after which he began his professional career as an assistant professor of physics at the University of Minnesota (1923–1924). From there he went on to the Carnegie Institution of Washington, DC, where he held a staff position as a mathematical physicist from 1924 to 1929, with a residency at the Eidgenössische Technische Hochschule (ETH), Zürich, in 1928. Breit would remain associated with the ETH as a research associate until 1944. For the next five years (1929–1934), he was professor of physics at New York University, followed by a professorship at the University of Wisconsin in Madison from 1934 to 1947. The latter appointment was interrupted by a two-year residency at the Institute for Advanced Study at Princeton (1935–1936), and his wartime work. He worked in the Naval Ordnance Laboratory during 1940 and 1941, at the Metallurgical Laboratory, University of Chicago, in 1942, became a member of the Applied Physics Laboratory, Johns Hopkins University (1942–1943), and headed physics at the Ballistic Laboratory, Aberdeen Proving Grounds (1943–1945). (His brief service with the fledgling Manhattan Project below.)

Breit’s postwar stay on the Madison campus was cut short by his acceptance of a professorship at Yale University in 1947. He remained at Yale, the last ten years as the first Donner chair, until he reached Yale’s mandatory retirement age of sixty-eight in 1968. He completed his professional career as distinguished professor of physics at the State University of New York at Buffalo, from which he retired to private life in Oregon in 1973.

Honors. Breit was elected to the National Academy of Sciences in 1939, and to the American Academy of Arts and Sciences in 1951. He was a fellow of the American Physical Society, Physical Society of London, Institute of Radio Engineers, and the American Association for the Advancement of Science. He was a member of the American Mathematical Society, American Geophysical Union, Washington Academy of Science, The Army Ordnance Association, Sigma Xi, and Phi Beta Kappa. He was awarded an honorary doctorate of science by the University of Wisconsin in 1954, the Benjamin Franklin Medal in 1964, and the National Medal of Science in 1968. He served, at various times in his career, as associate editor of Physical Review, Proceedings of the National Academy of Sciences, and Il Nuovo Cimento.

Breit married Marjory Elizabeth McDill on 30 December 1927, in Washington, DC, and acquired a stepson, Ralph Wycoff, from Marjory’s previous marriage. When he retired from the State University of New York (SUNY) Buffalo, he and Marjory moved into a retirement home near Salem, Oregon, where Marjory could be near her son and daughter-in-law. His health had begun declining in Buffalo, and Breit died on 13 September 1981.

Early Work: Geophysics. Breit’s first noteworthy item of research involved the experimental determination of the height of the “conducting” or “Kennelly-Heaviside” layer in the upper atmosphere. This ionospheric layer was inferred, nearly simultaneously in 1902 by Arthur Edwin Kennelly in the United States and Oliver Heaviside in the United Kingdom, to account for the long-distance propagation of very long wavelength radio waves. The auroras and magnetic storms pointed toward the circulation of large electrical currents in high regions of the atmosphere—a subject obviously within the province of the Carnegie’s Department of Terrestrial Magnetism (DTM). Breit’s partner in this effort was Merle Antony Tuve, whom he met in the summer of 1923 while at Minnesota, when he assisted Tuve on his MA thesis on UHF oscillator tubes. The tubes were experimental components in a project involving short radio waves, vacuum tubes, and related phenomena, including the Kennelly-Heaviside layer. Breit’s own MA thesis, at Johns Hopkins in 1920, had been on the transmission of electromagnetic waves in wireless telegraphy. Tuve’s interest in radio stemmed from his childhood in Canton, South Dakota, where he and his pal across the street, Ernest Orlando Lawrence, communicated in Morse code via home-crafted radio transmitters and receivers.

On joining the DTM in July of 1924, Breit began to plan a program for an in-depth study of the KennellyHeaviside layer; he was joined by Merle Tuve, who was then an instructor at Johns Hopkins while casting about for a PhD thesis topic. Breit’s scheme involved beaming short radio waves upward on a slant, reflecting them from the Heaviside layer down to Baltimore, where Tuve was conveniently available as an observer. Tuve, however, was somewhat skeptical of the critical reflection coefficient for such short waves, suspecting the waves would pass right through the reflecting layer, and suggested instead using pulses of conventional-length radio waves in a radio-echo sounding method first proposed by the English physicist William Francis Gray Swann. Swann was a former DTM staff member, where he started the first U.S. work on what was later called cosmic rays. He had left the department for a professorship at Minnesota, where he discussed his method at a seminar in 1922 that Tuve had attended. The new scheme involved comparing two sets of signals, one arriving by the line-of-sight path from the transmitter and the other scattered via the ionosphere. The time difference between the two paths would afford a measure of the height of the conducting layer.

Breit believed a large parabolic reflector, perhaps forty feet in diameter, located at the Broad Branch Road Campus of DTM, along with a much smaller receiving set in Baltimore, would be suitable for the attempt; however, funding limitations at DTM ruled that out. Instead, they availed themselves of a Naval Research Laboratory crystal-controlled transmitter located in Bellevue, Anacostia, a few miles from the DTM laboratory, which was modulated to transmit a series of short pulses. In June of 1925, they recorded pulse echoes at 4 MHz, received and recorded on the roof of the main building at DTM. In testing the apparatus, they noted occasional spurious signals, finally attributed to aircraft flying out of Washing-ton’s airport; in effect, they had unknowingly observed a radar signal.

On Breit’s urging, Joseph Sweetman Ames accepted Tuve’s contributions to the radio-echo project for his PhD dissertation in 1926, and, again on Breit’s suggestion, Tuve joined Breit at the DTM on 1 July of that year. In 1927, he and Breit were joined by the Norwegian Odd Dahl in the ionospheric work. However, several developments soon steered them away from this project. In England, the energetic physicist Edward Victor Appleton (whom Breit met during his postdoctoral stint in Europe) and his students at King’s College, London, were also working seriously on radio methods for investigating the ionosphere, but by a somewhat different method that would earn Appleton the Nobel Prize in Physics in 1947. At the same time, Breit’s interest was turning towards the emerging field of quantum mechanics, which led to his extended trip to Europe in 1928. Finally, the ongoing nuclear studies by Ernest Rutherford and colleagues at Cambridge had captured the attention not only of Breit and Tuve, but of John Ambrose Fleming, the assistant director at DTM; after all, the structure of the atomic nucleus was surely the fundamental key to the secrets of terrestrial magnetism! Before long, goaded by Fleming, the study of nuclear structure would occupy most of the working hours of Breit, Tuve, and Dahl.

Nuclear Physics Experiments. The key to a successful attack on the atomic nucleus, as Rutherford himself had declared, and as Breit realized early on in the United States, was to replace the weak flux of alpha particles from a radioactive source, as utilized by Rutherford in 1919 while still at Manchester University, with a potent artificial source of alphas or other particles, preferably protons, accelerated through an electric potential of millions of volts in a vacuum tube. However, there were limited methods of producing a million volts or higher in 1927. About the only device available was the Tesla transformer, in which a resonant primary coil of a few turns induces high alternating voltages in a multiturn secondary coil. Very high voltages could thereby be produced, especially if operated in oil under high pressure—the method by which the DTM team coaxed the coil to more than five million volts. However, the oscillatory character of the output potential, with a very short duty cycle, soon ruled the Tesla coil out for nuclear disintegration experiments. What was needed for energizing the discharge tube was a steady DC voltage. Just as Breit left the DTM, Tuve and Dahl, now joined by Lawrence Hafstad, adopted the electrostatic generator devised by Robert Van de Graaff as a highly suitable accelerator for precision experiments in nuclear research.

Breit sailed for Europe in August of 1928, where he spent his time following up on some theoretical work by Wolfgang Pauli and Werner Heisenberg. However, he cut his year abroad short and returned to the United States in January 1929. In view what he saw as the untruthful nature of theoretical physics and the need for new data about the nucleus, Breit felt that it was more desirable to return to Washington to assist in obtaining this information through investigations into high-voltage developments.

However, back at DTM, Breit found himself in a situation less happy than it had been before his sojourn abroad. He had left DTM partly because his personal relations with his colleagues had reached an impasse. Now his relationship with Tuve was, if anything, more difficult, and Breit left DTM in August 1929 to accept a position at New York University. Curiously, in the years to come he cooperated closely with Tuve’s nuclear physics team, offering sound theoretical knowledge and analysis of their experimental results via letters and occasional visits with Tuve in New York.

Theory. In New York, Breit, too, continued high voltage experiments with various collaborators on the ground floor of a large building at University Heights in the Bronx. However, increasingly his time was spent, at New York and later in Madison and New Haven, on theory and advising students and colleagues on proposed experiments and their results. Many have nostalgic memories of the joint Columbia–New York University theoretical seminar conducted by Isidor I. Rabi and Breit, in Room 831 in the Pupin Laboratory, often followed by a late evening discussion in Rabi’s Riverside Drive apartment. Breit’s range of contributions was sufficiently diverse that only a full-length biography could do them justice. For a starter, they encompassed fine and hyperfine structures, magnetic moments, and the nuclear isotope shift. Altogether, Breit published, alone and with colleagues, some 320 papers, according to McAllister Hull. His definitive work, carried out at Princeton with Eugene P. Wigner on the resonance theory of the capture of slow neutrons, appeared in 1936. The same year saw his famous paper, with Edward U. Condon and Richard D. Present, on the theory of the scattering of protons by protons—the original objective at DTM as an experimental tool for probing the short-range attractive force between the constituents of atomic nuclei.

At Wisconsin, as in New York, Breit began his tenure with the construction of an accelerator, of the Cockcroft-Walton type pioneered in Cambridge, and this modest experimental program inspired the work of Ray Herb and colleagues in their classic Van de Graaff experiments on proton-proton scattering begun shortly before World War II and resumed after the war. His paper on evidence concerning the equality of neutron-neutron and proton-proton forces appeared in 1950. With McAllister H. Hull and Robert L. Gluckstern, he explored, in 1952, the possibility of heavy-ion bombardment in nuclear studies. With Gluckstern he studied Coulomb excitation in great detail, and Hull was his partner in nucleon-scattering studies over a number of years. At Yale he collaborated with his student Gerald E. Brown, who later rose to high prominence in theoretical nuclear physics. It might be added that Robert K. Adair, who knew Breit well at Yale, believed that once ensconced in New Haven, Breit’s creativity declined somewhat in that he largely spent his time going over in increasing depth research that had gained his reputation in the earlier years. Be that as it may, Breit’s last concern with accelerators was apparently at Yale in 1964, with the proposal for a “meson factory” as a source of an intense beam of pi-mesons for the study of light nuclei.

Wartime Contributions. It was Breit who proposed, at a National Research Council meeting in April 1940, after experiments in 1939 confirmed the military potentials of nuclear fission, the voluntary censorship of publications of uranium studies—a practice adhered to by most Allied scientists during Word War II. The same month, Breit was the second person to be appointed to the Advisory Committee on Uranium, chaired by Lyman Briggs of the Bureau of Standards, charged with the coordination of “Rapid Rupture”: fast neutron bomb studies and overall evaluation of potential weapons problems. In January 1942, when Arthur Holly Compton organized the Metal-lurgical Laboratory in Chicago, he chose Breit to supervise bomb studies and lecture Met Lab staff on bomb theory that might guide plans for a plutonium bomb. When J. Robert Oppenheimer arrived, Compton made him a consultant, formally under Breit. However, Breit and Oppenheimer did not get along, with Breit’s concern over bomb theory leaking out, and Oppenheimer’s concern that the theory was not disseminated fast enough. Breit resigned, replaced by Oppenheimer, and left the fledgling Manhattan Project for ballistic research, as sketched earlier.

As for Breit versus Oppenheimer, John Wheeler had interesting things to say about the two leaders of theoretical nuclear physics in the United States. On receiving a National Research Council Fellowship for 1933–1934, he had to decide under whom to work, Oppenheimer or Breit. Having talked with both of them, he felt he could have worked with either.

In personality they were utterly different. Oppenheimer saw things in black and white and was a quick decider. Breit worked in shades of gray and could be described in those words that Charles Darwin used in speaking of his own most important qualities: “The love of science—unbounded patience in long reflecting over any subject— industry in observing and collecting facts—and a fair share of invention ...” Being temperamentally uncomfortable with quick decisions, and attracted to issues that require long reflections, I chose to work with Breit. (Wheeler, 1979, p. 229)

Retirement Symposium. At the aforesaid symposium in honor of Breit’s retirement at Yale in 1968, a multitude of his colleagues and former students from around the world filled the Yale Law School Auditorium. Chaired by Robert K. Adair and Robert Gluckstern, the symposium speakers were as follows: Hans Bethe, D. Allan Bromley, Gerald Brown, Ray Herb, Vernon Hughes, McAllister Hull, Merle Tuve, and Eugene Wigner. The talks are all reprinted in Facets of Physics, listed in the bibliography below. The banquet speakers included Henry Margenau, Isidor Rabi, Victor Weisskopf, and John Wheeler, the toastmaster. In his banquet remarks, Margenau recalled the waning of his own interest in nuclear physics due to imposed wartime secrecy:

[M]y spirits rose when Gregory, having conceived of an important problem, offered me collaboration. I looked at it and it seemed intriguing. Closer study of what Gregory had already done and what would have been my task in bringing the calculations to a conclusion made it clear to me that nearly all the work had already been accomplished. The generosity involved in this offer was overwhelming, and I decided on what may have been an unwise surge of propriety or pride to decline the kind suggestion to share the honor of that publication.

Thus I forfeited a chance to scientific stature by refusing the kind of bid from which many in this audience have profited; for collaboration with Gregory Breit was a road to distinction in physics, a road on which many have traveled, led by a master’s hand. (Facets of Physics, p. 188)

Breit’s response included recollections of a few “giants” of physics who “lived for essential ideas,” including Einstein, Rutherford, Kamerlingh Onnes, Bohr, and especially Ehrenfest, whose “clarity of thought regarding essential steps in theoretical physics was of utmost importance to him” (pp. 193–194). The same year, 1968, President Johnson presented Breit with a National Medal of Science for his contributions to the first atom smashers and ordnance developments.


A selected bibliography is given by McAllister Hull in his biographical memoir (see below), the selection of which was “intended to note the [papers] that initiated a study [or] made a significant advance.” Breit’s geophysical papers, coauthored with Merle Tuve, are listed in the references of Gilmor’s paper. A complete bibliography is found in Bromley and Hughes, eds., Facets of Physics.


“The Distributed Capacity of Inductive Coils.” Physical Review 17 (1921): 649–677.

With Merle Antony Tuve. “A Radio Method of Estimating the Height of the Conducting Layer.” Nature 116 (1925): 357.

With Merle Antony Tuve. “Radio Evidence of the Existence of the Kennelly-Heaviside Layer.” Journal of the Washington Academy of Sciences16 (1926): 98.

With Merle Antony Tuve. “The Production and Application of High Voltage in the Laboratory.” Nature 121 (1928): 535.

With Merle Antony Tuve and Odd Dahl. “Effective Heights of the Kennelly-Heaviside Layer.” Proceedings of the Institute of Radio Engineering 16 (1928): 1236–1239.

“On the Possibility of Nuclear Disintegration by Artificial Sources.” Physical Review 34 (1929): 817–818.

With Merle Antony Tuve and Lawrence R. Hafstad. “The Application of High Potentials to Vacuum Tubes.” Physical Review 35 (1930): 66–71.

With F. L. Yost and John Archibald Wheeler. “Coulomb Wave-Functions in Repulsive Fields.” Physical Review 49 (1936): 174–189.

With Eugene Wigner. “Capture of Slow Neutrons.” PhysicalReview 49 (1936): 519–531.

With Edward Uhler Condon and Richard D. Present. “Theory of Scattering of Protons by Protons.” Physical Review 50 (1936): 825–845.

With L. E. Hoisington, S. S. Share, and H. M. Thaxton. “The Approximate Equality of the Proton-Proton and Proton-Neutron Interactions for the Meson Potential.” Physical Review 55 (1939): 1103.

“The interpretation of resonances in nuclear reactions.” PhysicalReview 58 (1940): 506–537.

With Arthur A. Broyles and McAllister H. Hull, Jr. “Sensitivity of Proton-Proton Scattering to Potentials at Different Distances.” Physical Review 73 (1948): 869–876.

With Gerald E. Brown. “Effect of Nuclear Motion on the Fine Structure of Hydrogen.” Physical Review 74 (1948): 1278–1284.

“Evidence Concerning Equality of n-n and p-p Forces.” PhysicalReview 80 (1950): 1110–1111.

With McAllister H. Hull Jr., and Robert L. Gluckstern. “Possibilities of Heavy Ion Bombardment in Nuclear Studies.” Physical Review 87 (1952): 74–80.

With McAllister H. Hull Jr. “Advances in Knowledge of Nuclear Forces.” American Journal of Physics 21 (1953): 184–220.

With Marvin E. Ebel. “Nucleon Tunneling in N14 + N14 Reactions.” Physical Review 103 (1956): 679–701.

With Robert L. Gluckstern and J. E. Russell. “Reorientation Effect in Coulomb Excitation.” Physical Review 103 (1956): 727–738.

With McAllister H. Hull Jr., Kenneth E. Lassila, H. M. Ruppel, and F. A. McDonald. “Phase Parameter Representation of Neutron-Proton Scattering from 13.7 to 350 MeV. II.” Physical Review 128 (1962): 830–832.

With McAllister H. Hull Jr., Kenneth E. Lassila, K. D. Pyatt Jr., and H. M. Ruppel. “Phase parameter representation of proton-proton scattering from 9.7 to 345 MeV. II.” Physical Review 128 (1962): 826–830.


Bromley, D. Allan, and Vernon W. Hughes, eds. Facets of Physics. New York: Academic Press, 1970.

Gilmor, C. Stewart. “The Big Story: Tuve, Breit, and Ionospheric Sounding, 1923–1928.” In The Earth, the Heavens and the Carnegie Institution of Washington, edited by Gregory A. Good. History of Geophysics, vol. 5. Washington, DC : American Geophysical Union, 1994.

Hull, McAllister H., Jr. “Gregory Breit.” Physics Today (October 1983): 102–104. Obituary.

———. “Gregory Breit: July 14, 1899–September 11, 1981.” Biographical Memoirs, vol. 74. Washington, DC: National Academy of Sciences, 1998. The most extensive obituary notice and principal account of Breit’s life and work.

Kihss, Peter. “Dr. Gregory Breit, Early Authority on Atom Weapons, Is Dead at 82.” New York Times, 22 September 1981. A multicolumn obituary.

Wheeler, John. Some Men and Moments in the History of NuclearPhysics. Minneapolis: University of Minnesota Press, 1979.

Per F. Dahl