SERBER, ROBERT

(b. Philadelphia, Pennsylvania, 14 March 1909; d. New York, New York, 1 June 1997), nuclear and particle physics.

Serber’s long and distinguished career will probably be best remembered for the important contributions he made in producing the world’s first nuclear weapons. For two years he served as a group leader at the secret Los Alamos Laboratory, working in Hans Bethe’s Theoretical Division. On Tinian Island he prepared the bombs for delivery against Japan. Only a few weeks later he would travel to Hiroshima and Nagasaki, witnessing the destruction firsthand. But Serber’s interesting life and productive scientific career transcend the short time he spent at Los Alamos. Foreshadowing the fate of his close friend and mentor J. Robert Oppenheimer, he endured the injustices

of McCarthy-era America by having a security clearance request rejected by Naval Intelligence. Despite this, he would serve as a consultant to the Brookhaven National Laboratory for nearly two decades. Serber also mentored a myriad of scientists during his years at Columbia University, including 1972 Nobel laureate Leon Cooper. His imprints on Los Alamos, Columbia University, and the field of theoretical physics remain visible over a decade after his passing.

Youth On 14 March 1909, Robert Serber was born in Philadelphia to David and Rose Frankel Serber. His paternal grandfather had immigrated to the United States from Russia in the mid-1880s. David Serber, a native of Russia, was only a toddler at the time. Robert’s mother, Rose Frankel, was born in Philadelphia to Polish immigrants a few years later.

Rose died when Robert was very young, leaving David a widower. Several years later, during Robert’s high school years, David married Frances Leof. Frances’s uncle, Morris Leof, was a well-known physician who owned a large house in a nearby neighborhood. The house, located at 322 South Sixteenth Street, was a favorite haunt for Jewish artisans and intellectuals, and soon it would become a refuge for Robert. Here he developed friendships with Dr. Leof’s children, Madelin, Milton, and Charlotte, and was introduced to the family’s socialist politics. This close connection with his stepmother’s family would shape Robert’s life for years to come.

Robert’s father David, a liberal Democrat, became a wealthy lawyer, which afforded the family a life of comfort. Robert enjoyed gymnastics, swimming, and school, where his curriculum included the study of chemistry, math, and physics. An interesting passage in his Central High Yearbook states: “His wonderful inventive brain has invented inventions galore. The trouble is that none is practical … (Edison must step fast or else he will soon have a strong rival).” Robert graduated in 1926 and went on to Lehigh University in nearby Bethlehem, Pennsylvania, where he earned a BS in engineering physics.

After receiving his degree in 1930, Robert decided to take the advice of his Lehigh professors and left Pennsylvania to attend graduate school at the University of Wisconsin. He earned an $800-per-year salary (a considerable sum, considering the declining economic state of the country) as a teaching assistant and gained valuable experience as a lecturer. Robert was fortunate enough to study under John Van Vleck, one of the nation’s leading physicists and a future Nobel laureate. Van Vleck introduced him to the new field of quantum mechanics. To his professor’s delight, Robert delivered his first lecture to the American Physical Society in December 1931 and published his first Physical Review article the following spring.

While attending Lehigh, Robert had maintained close ties to the Leofs. He started to lose contact with the family until Charlotte, Morris Leof’s daughter, decided to write him a letter in late 1931. On a trip home the following summer, Robert and Charlotte started dating. The two were married in Philadelphia less than a year later, in spring 1933, and took up residence in an apartment back in Madison.

Oppenheimer In 1934, Serber was awarded his doctorate in theoretical physics as well as a National Research Council Fellowship. At Van Vleck’s suggestion, he decided to work with Eugene Wigner at Princeton. The twelve hundred dollar prize that accompanied the award would easily support him and Charlotte for the following year, so the couple packed for the journey to New Jersey. The trip included a stop at the University of Michigan where the Serbers attended the annual physics summer school and met a young professor from Berkeley named J. Robert Oppenheimer. “His mind was so quick and his speech so fluent,” Serber states in his memoir, “that he dominated nearly every gathering. He was generous and could be very charming. At Ann Arbor that summer I soon became fascinated by him” (Serber, 1998, p. 25) Serber was so impressed that he decided to spend his fellowship working with “Oppie” at Berkeley instead of going to Princeton.

At Berkeley, Serber quickly fell under Oppenheimer’s “spell.” The two became very close friends, and spent a great deal of time with each other. Not only was Serber introduced to nuclear physics, but also fine foods, wine, and art. This complete education included access to Oppenheimer’s colleagues at Caltech, Stanford, and Ernest O. Lawrence’s Radiation Laboratory. Only a year later, the Serbers even started joining Oppenheimer on his vacations. During one of these trips, they visited a small ranch Oppenheimer had acquired in northern New Mexico, not too far from a place called Los Alamos. Each year, from 1935 to 1941, this pilgrimage to New Mexico was repeated by the trio.

When Serber’s fellowship ran out in 1936, Oppenheimer secured a position for him as a research assistant. In these years Oppenheimer began taking an interest in left-wing politics at the behest of his girlfriend, Jean Tat-lock. With help from Oppenheimer, Charlotte established a local chapter of the Medical Aid Committee for the Spanish Loyalists, a communist-sponsored organization set up to aid the Spanish government in the civil war being fought against the fascist forces of Francisco Franco. Activities such as this would haunt the Serbers, and especially Oppenheimer, years later.

In 1938 Serber became an assistant professor at the University of Illinois. He was not anxious to leave Berkeley, but Charlotte convinced him to take advantage of the opportunity. During his years at Illinois he continued to refine his skills as a lecturer, though he often failed to return papers to his students on time. Another deficiency was his inability to recall the names of his students, and as a result Serber was prohibited from teaching the larger undergraduate classes. This period was also marked by his publication of several outstanding scientific articles, many of which were coauthored by Oppenheimer. The productive collaboration between the two would continue into the 1940s. Ironically, events thousands of miles away were about to result in a reunification at Berkeley.

The 1938 discovery of fission in Germany made atomic bombs possible. The public announcement of this discovery, made by Niels Bohr at a theoretical physics conference being held in Washington, D.C., both excited and alarmed physicists. Though an important scientific discovery, it came as Nazi Germany, Imperial Japan, and Fascist Italy were stepping up their territorial conquests. A potential enemy armed with an atomic bomb would be formidable. Despite the significance of this discovery, the United States initially failed to respond in a vigorous manner. Albert Einstein’s famous letter to President Franklin Roosevelt stimulated some research, but it was not until the Japanese attack on Pearl Harbor and Enrico Fermi’s successful production of a fission chain reaction that work on atomic matters accelerated in the United States.

Shortly after Pearl Harbor, Oppenheimer asked Serber to return to Berkeley. Oppenheimer had been given the task of developing an atomic bomb and wanted Serber to handle major portions of the undertaking. At Berkeley, Serber worked on the general properties of atomic bombs including questions of the masses of material needed and the energy release expected. He also directed studies of fissionable material, the behavior of neutrons in a chain reaction, as well as the hydrodynamics of a nuclear explosion. Also at Berkeley, Serber made estimates of the properties and amounts of material for the planned Water Boiler reactor, so named because it used an aqueous solution. In 1944, the Water Boiler became the first reactor in the world to go critical using enriched uranium. After his year at Berkeley, Serber knew more about atomic bomb design than anyone else in the world.

In the summer of 1942, at the request of the National Bureau of Standards, Oppenheimer convened a conference at the University of California with Hans Bethe, Edward Teller, and others to analyze existing research on fission. During a discussion of how to make a fission bomb, Teller, out of the blue, proposed a hydrogen bomb. As Serber recalled in 1993, “And then a really remarkable thing happened. Edward brought up the super, a detonation wave in liquid deuterium heated by an atomic bomb. Everybody turned eagerly to discuss the super forgetting all about the atomic bomb as if that was an accomplished fact already!” (Serber, 1994, p. 60). Teller, before anyone else, understood that an atomic bomb could produce the stellar temperatures needed to ignite a hydrogen bomb. With further debate, however, the excitement over the “super” quickly died. Even if an atomic bomb could ignite deuterium, radiation cooling, known as the inverse Compton effect, would stop the thermonuclear process. The conference went on to decide that an atomic bomb was achievable and could be developed in a relatively short period. As Serber noted many years later, there seemed to be an implicit assumption “that I had the fission bomb under control, that there was nothing to worry about” (Serber, 1992, p. xxxi).

In early 1943 Serber moved to New Mexico to assist Oppenheimer in setting up the Los Alamos laboratory. Since most of the incoming scientists knew very little, if anything, about atomic bombs, Oppenheimer asked Serber to hold a series of indoctrination lectures. Over the course of two weeks, Serber gave five lectures that shared his extensive knowledge (in reality the sum of known knowledge) of nuclear weapons physics. The first lecture began with a bald statement of the purpose of the Los Alamos Project: “The object of the project is to produce a practical military weapon in the form of a bomb in which the energy is released by a fast neutron chain reaction in one or more of the materials known to show nuclear fission.” Edward Condon took notes at each lecture that he and Serber would edit for internal publication. These notes became LA-1, the first technical report produced at Los Alamos. LA-1 served as the research blueprint for subsequent work at Los Alamos. In 1992 the University of California Press published Serber’s lectures under the title The Los Alamos Primer: The First Lectures on How to Build an Atomic Bomb.

After delivering the five primer lectures, Serber became a group leader in Bethe’s Theoretical Division. Serber’s group, T-2, had the responsibility of accurately predicting the critical mass of an atomic bomb by developing an understanding of the behavior of neutrons. Serber also assumed responsibility for the theoretical design of the gun-type weapon known as Little Boy. In addition to these two major tasks, Serber worked on implosion bomb physics. Implosion, the use of high explosives to create supersonic shockwaves to compress plutonium, required a great deal of instrumentation, much of which Serber had responsibility for. As part of his implosion work, Serber invented the RaLa (radio-lanthanum) method of analyzing the implosion process. The RaLa method proved valuable and would be used by Los Alamos until 1962.

On 16 July 1945 Serber witnessed the first detonation of an atomic bomb, the Trinity Test, which was conducted in the desert of southern New Mexico. Standing about twenty miles from ground zero, Serber looked directly at the detonation without eye protection and was momentarily blinded by the bright flash of light. He later wrote that “The grandeur and magnitude of the phenomenon were completely breathtaking” (Serber, 1998, p. 79).

Following the Trinity test, Serber traveled to Tinian Island in the Pacific to join the 509^th Composite Group, which was making preparations for the combat use of the atomic bombs against Japan. The 509^th commander, Paul Tibbets, asked Serber to verify that the strike aircraft would survive the detonation of an atomic bomb. He did so. Slated to fly on the Nagasaki mission, Serber was thrown off the photo plane at the last minute because the supply sergeant had not given him a parachute. As Serber wryly noted, it did not matter in the long run, because the pilot of the photo plane did not make contact with the strike craft and missed the drop completely.

After the surrender of Japan, Serber was chosen to assess bomb damage at Hiroshima and Nagasaki, where he and several others took photographs, collected bomb debris, and made initial estimates of the yields of Little Boy and Fat Man. Although the mission was plagued by logistical problems, it was completed without incident.Serber was back in Los Alamos on 15 October, one day before Oppenheimer resigned as director of the laboratory.

Cold War Physics and Politics After the war, professional opportunities abounded for physicists for the first time in Serber’s career. Illinois offered him a full professorship, but future Nobel laureates Luis Alvarez and Edwin McMillan (new friends made at Los Alamos) secured the position of Theoretical Division leader for him at Lawrence’s Berkeley Radiation Laboratory. Serber did not sever his ties with Los Alamos, however, and agreed to serve on a committee to assess the feasibility of building the hydrogen bomb.

Oppenheimer spent less and less time at Berkeley because of duties as an advisor on atomic energy. Serber often lectured in his stead, and eventually inherited his post in the Physics Department after Oppenheimer agreed to lead Princeton’s Institute for Advanced Study. Despite his responsibilities to the Physics Department and the Radiation Laboratory, Serber still managed to publish more articles in 1947 than in any other year of his career. In the classroom he focused on theoretical physics, while his work at the laboratory offered him the opportunity to pursue experimental work using particle accelerators, cyclotrons, and synchrotrons. But Serber was about to face challenges outside the laboratory.

By the late 1940s, the country was changing. The Cold War was beginning to set in and security requirements were being reexamined; a prelude to the “Red Scare.” In 1948, the Atomic Energy Commission (AEC) launched an investigation into Serber’s background due to his previous associations with several known and suspected members of the Communist Party. Oppenheimer, who had access to the final report as a member of the AEC’s General Advisory Committee (GAC), informed his friend that he had “passed with glowing praise.” “But,” Serber later wrote, “I … found the experience humiliating and frightening, and resented having been put through it” (Serber, 1998, p. 165).

Others would endure similar hearings, especially after Senator Joseph McCarthy’s reign of political terror began. McCarthy fed off the hysteria created by Communist victories in China, the Soviet Union’s first successful nuclear test in August 1949, and stalemate on the Korean Peninsula. Many in the scientific community, including Lawrence, Alvarez, and Teller, favored initiating a crash program to build the “super,” but Serber felt such an effort was not necessary and that such a device could probably not be built anyway. The GAC recommended that thermonuclear weapons research should not go forward, but President Harry Truman felt otherwise and ordered the development program to proceed rapidly.

Serber found himself in the middle of other controversies as well. The University of California (UC) regents chose to require all UC employees to take an oath of loyalty to the United States or face termination. Though Serber agreed to sign the oath, other top scientists chose to leave the university. Others still, who refused to sign, were fired.

Meanwhile, scientists from around the country were divided over the explosive political issues of the time. The informal leaders of these groups were Oppenheimer, representing the liberals, and Lawrence, who harbored a much more conservative outlook. Serber remained loyal to his very close friend Oppenheimer, though he had developed a deep respect for Lawrence during his years at the Radiation Laboratory. But if Serber had to choose, there was no question that he felt more comfortable in the Oppenheimer camp. Isidor Rabi, a good friend and former consultant to Los Alamos, helped persuade Serber to come to Columbia University and work with him. After struggling to make a decision, the Serbers agreed to leave California and much of its controversy for New York in mid-1951.

Upon arriving at Columbia, Serber inherited George Pegram’s office in the university’s famous Pupin Laboratory. He settled into his new academic life by teaching a graduate course in quantum mechanics, working on atomic beam measurements for Rabi and taking on his first PhD candidate at Columbia, future Nobelist Leon Cooper. During his Columbia years, Serber collaborated with Abraham Pais on meson studies and developed the Serber-Dancoff method, a more accurate technique for analyzing strong coupling.

Unfortunately, Serber would not be able to escape the Cold War politics of the era. In early 1953, Naval Intelligence denied his request for a security clearance needed to attend a physics conference in Japan. Serber still had his AEC clearance and neither he nor Charlotte had been politically active since World War II, yet the navy was unwilling to accept responsibility for granting a clearance. Serber recalls, “I was really offended, and my resentment played a significant part in my later refusal to become a consultant to the Department of Defense during the Vietnam War” (Serber, 1998, p. 175). Only a year later, Oppenheimer’s AEC security clearance would be revoked on similarly baseless grounds, infuriating Serber and rocking the scientific community.

Later Activities Although the navy rejected his request for a clearance to visit Japan, his AEC clearance enabled Serber to work at Brookhaven National Laboratory, just up the highway from New York City. Once a week, for the better part of two decades, he would make the trip to Brookhaven where he served as a consultant. This position allowed him to contribute to many of the institution’s projects, including the construction of the Cosmotron, the world’s first billion-electron-volt accelerator.

The Serbers enjoyed the next several years in New York, but made time to journey around the world. Their travels took them to England, France, Italy, Turkey, Israel, India, Cambodia, Hong Kong, and Japan. In 1959 the couple went to Kiev, in the Soviet Union, for an international physics conference; times had clearly changed. Back in New York, the Serbers often sailed off Long Island Sound and even made a voyage to the Virgin Islands. It would be the first of many trips to the Caribbean for Serber.

In 1963, the Oppenheimers went to Brookhaven where Oppie would give the annual Pegram Lecture. By this time his physical state was rapidly deteriorating due to the loss of his clearance, which most agree broke his spirit, and years of heavy smoking. Only a few years later, in February 1967, Oppenheimer would die of throat cancer. Unfortunately for Serber, another tragedy came only months later. Charlotte was suffering from Parkinson’s disease, and soon fell into a deep depression brought on by her symptoms. That May, she ended her own life.

After Charlotte’s death, Serber’s life took on a new direction. At the urging of Kitty Oppenheimer, Robert’s widow, Serber organized the first of several annual theoretical physics conferences in honor of Oppenheimer. Serber also became the president of the American Physical Society (APS) in 1971. Serving at the height of social and campus protests against the Vietnam War, he had the unenviable duty of steering the society through treacherous waters. Serber firmly believed that the APS should concern itself solely with matters of science and leave politics to others. As a member of the APS nominating committee, Serber took the lead in nominating the first woman to be president of the society, Chien-Shiung Wu. Her selection ultimately led to the promotion of women in science both as teachers and as science administrators.

Serber’s work with Kitty on the annual physics conference led to a renewal of their friendship. In 1972, while on sabbatical, he began an extended sailing expedition with Kitty. While off the coast of Panama, Kitty became ill and was hospitalized in Panama City. She died on 27 October. Serber helped the two Oppenheimer children, Peter and Toni, with funeral arrangements. He remained close to Toni and spent many vacation days with her at the Oppenheimer cottage on St. John.

In 1975 Serber became chair of the Physics Department at Columbia, a post he held until his retirement at the end of the 1978 academic year. He married Fiona St. Clair, a longtime friend from St. John, in 1979. A son, William, was born in November 1980, joining Fiona’s son Zachary as part of the family.

After his retirement from Columbia, Serber returned twice to Los Alamos. His 1983 visit was part of the laboratory’s fortieth anniversary, where he and many of his colleagues gave talks and lectures related to the scientific work of the wartime laboratory. Serber returned again for the laboratory’s fiftieth anniversary in 1993, accompanied by his son William.

Robert Serber died 1 June 1997 following surgery for brain cancer. He was eighty-eight. As his longtime colleague Wolfgang Panofsky said in Serber’s New York Times obituary, “Serber’s talent was being able to comprehend a theory at its widest and narrowest points and to communicate that information to others.” This ability enabled Serber to play an important role in the advancement of physics during one of its most exciting periods.

BIBLIOGRAPHY

The Niels Bohr Institute at the Center for the History of Physics, American Institute of Physics, has several oral history interviews of Serber.

WORKS BY SERBER

“The Theory of the Faraday Effect in Molecules.” Physical Review 41 (1932): 489–506.

With J. Robert Oppenheimer. “On the Stability of Stellar Neutron Cores.” Physical Review 54 (1938): 540L.

With S. M. Dancoff. “Nuclear Forces in Strong Coupling Theory.” Physical Review 61 (1941): 53–58.

“The Spins of Mesons.” Physical Review 75 (1949): 1459A.

With A. Pais. “Interaction between k-Particles and Nucleons.”Physical Review 99 (1955):1551–55.

With R. P. Feynman and F. de Hoffmann. “Dispersion of the Neutron Emission in U-235 Fission.” Journal of Nuclear Energy 3 (1956): 64-69.

Serber Says: About Nuclear Physics. Singapore: World Scientific,1987.

The Los Alamos Primer: The First Lectures on How to Build an Atomic Bomb. Berkeley: University of California Press, 1992.

“Peaceful Pastimes: 1930–1950.” Annual Review of Nuclear and Particle Science 44 (1994): 1–26.

With Robert Crease. Peace and War: Reminiscences of a Life on the Frontiers of Science. New York: Columbia University Press, 1998.

OTHER SOURCES

Bird, Kai, and Martin J. Sherwin. American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer. New York: Knopf, 2006.

Conant, Jennet. 109 East Palace: Robert Oppenheimer and the Secret City of Los Alamos. New York: Simon & Schuster, 2005.

Crease, Robert. Making Physics: A Biography of Brookhaven National Laboratory, 1946–1972. Chicago: University of Chicago Press, 1999.

Hawkins, David, Edith C. Truslow, and Ralph Carlisle Smith. Project Y: The Los Alamos Story. New York: Tomash Publishers, 1983.

Hewlett, Richard G., and Oscar E. Anderson Jr. The New World: A History of the United States Atomic Energy Commission Volume I, 1939–1946. Berkeley: University of California Press, 1990.

Hoddeson, Lillian, et al. Critical Assembly: A Technical History of Los Alamos during the Oppenheimer Years, 1943–1945. New York: Cambridge University Press, 1993.

Alan B. Carr

Roger A. Meade