Tolman/Bacher House

The Manhattan Project

Both Richard Tolman and Robert Bacher were instrumental to the success of the Manhattan Project during the Second World War, and they devoted a large part of their professional lives to considering and controlling the implications of nuclear energy after the war, both in terms of nonproliferation and disarmament and future peacetime applications. Caltech during the 1940s, like many American universities, experienced an unprecedented call to join efforts aiding national defense strategies from a science and technology point of view. Robert A. Millikan’s retirement as chairman of the Executive Council in 1945 and Lee DuBridge’s arrival as the institute’s first president marked the end of an era in Caltech’s history in more ways than one. More than $80 billion in federal funding went to the university for research and development of weapons and other wartime technologies during the conflict, and the entanglement of military and civilian scientific goals and methods profoundly marked the postwar period.

Richard Tolman and Robert Bacher receive the Medal for Merit, the highest civilian decoration of the United States, from Lt. General Leslie Groves on January 12, 1946.

Richard Tolman was a young professor at the University of Illinois in 1918 when he took on his first role as scientific advisor, in the capacity of Chief of the Disperoid Section of the Chemical Warfare Service during World War I. After the war, he became the Associate Director, and later the Director, of the Fixed Nitrogen Research Laboratory within the Department of Agriculture, which was charged with studying the nitrogen products used in fertilizers and explosives. He left this post in 1922 to accept a faculty appointment at the California Institute of Technology, which he held until his death in 1948.

Second Memorandum on the Los Alamos Project, describing living conditions for families relocating to the site.

In June of 1940, Tolman was appointed a member and elected Vice-Chairman of the National Defense Research Committee (NDRC), which had just been formed by order of President Roosevelt at the urging of Vannevar Bush, President of the Carnegie Institution. This organization was intended to facilitate collaboration between military and civilian research and development efforts, and was superseded by the Office of Scientific Research and Development (OSRD) a year later. Tolman served as Chairman of Division A, which was devoted to armor and ordnance and included studies of structural defense, propulsion, ballistics, proximity fuzes for shells, and guided projectiles. The National Bureau of Standards’ Advisory Committee on Uranium was absorbed into the NDRC in 1940 and later became the S-1 Committee of the OSRD, under which the Manhattan Project was organized. Brigadier General Leslie Groves assumed command of the Project in September of 1942, and Tolman, along with Harvard President and Chairman of the NDRC James B. Conant, were appointed as his scientific advisors. In this capacity, Tolman served as the principal liaison between the NDRC and Los Alamos. When the Quebec Agreement established a Combined Policy Committee in August of 1943 to coordinate weapons development between the United States, Canada, and the United Kingdom, Tolman became the scientific advisor to the U.S. representatives, Bush and Conant.

Page from the notebook that Robert Bacher kept during his first visit to Los Alamos in 1943.

Like Tolman, Robert Bacher was intimately involved in the development and work of the Manhattan Project. In the spring of 1942, he and the associate director of the MIT Radiation Lab, I. I. Rabi, were approached by Robert Oppenheimer for advice on setting up a laboratory to work on a nuclear weapon. To their dismay, they learned that the project had been conceived as a military operation, with all participants required to enter military service. Both Rabi and Bacher refused to join under these circumstances, and their strong reaction prompted Oppenheimer and his superiors, Conant and Groves, to reconsider the decision. In February of the following year, all three agreed that the lab would be a civilian operation until enough fissionable material had been accumulated for a bomb, at which point it would become a military project.

Letter from J. Robert Oppenheimer, director of the Manhattan Project, to Robert Bacher on April 28, 1943, urging him to accept the “direction of the experimental physical work at Los Alamos.”

The following April, Bacher attended a two-week conference during the unofficial opening of the laboratory at Los Alamos, where he heard lectures from Tolman and Fermi, among many others, and participated in discussions. The first time Oppenheimer asked him to join the lab, he refused, citing ambiguities as to his actual role in the project and the wisdom of devoting resources to an atomic bomb rather than other military technologies, such as radar. In response, Oppenheimer praised his gift for leadership and administration and asked him to direct the experimental physics department. Bacher’s acceptance letter included the caveat that he would leave the project as soon as it became a military operation, a transition that never occurred.

Clip from The Washington Daily News, August 7, 1945, on the development of the atomic bomb and peacetime applications of atomic energy.

The Bachers moved to Los Alamos in June, 1943, and the Physics Division set to work taking measurements of neutron cross-sections for many types of nuclear reactions. The lab was reorganized a year later to address the use of plutonium in nuclear weapons, and Bacher transitioned to director of the bomb physics section, also known as the G Division (“G” for “gadget”). Leading the team responsible for achieving the symmetry required by the implosion bomb design, he was a key part of the successful Trinity test in the Alamagordo desert on July 12, 1945. Bacher supervised the assembly of the plutonium bomb core and drove it to the test site in his station wagon to be installed with the rest of the bomb. Three weeks after the Trinity test, similar devices were used at Hiroshima and Nagasaki, leading to Japanese surrender and the close of World War II.

On January 12, 1946, both Tolman and Bacher received the United States Medal for Merit--the nation’s highest civilian honor--for their service during the war, and two years later, Tolman also earned the rank of honorary officer of the Order of the British Empire for his contributions to the Allied cause. For many years afterward, both continued their work as scientific advisors to government officials on matters relating to nuclear energy. Tolman was appointed chief technical advisor to the U.S. Delegate on the United Nations Atomic Energy Commission (UNAEC), the first meeting of which took place in June of 1946. Together with Oppenheimer, both Tolman and Bacher served on the Scientific and Technical Subcommittee (STS) of the UNAEC, which developed and assessed plans for nuclear disarmament and nonproliferation with representatives from the other nations on the Security Council. Tolman and Bacher worked very closely together during this time, spending every weekday for two months working out all aspects of the control and inspection of nuclear weapons. By September of that year they produced a report that was unanimously approved by the members of the STS.

Final paragraph of “Survey of the Sciences,” a commencement speech given by Richard Tolman at Brown University in 1947.

Tolman also headed the Committee on Declassification for the U.S. Atomic Energy Commission (AEC). In the fall of 1945, he was asked by Groves to produce a report laying out guidelines for the declassification of information related to atomic energy. Robert Bacher was among the six scientists he selected to join him on what became known as the Tolman Committee, which produced its first report on November 17 of that year. In order to be deemed acceptable for declassification, information would have to either contribute to the advancement of military or civilian aspects of science and technology or be considered already known or easily obtained by the outside community. According to the report, nothing that could jeopardize the military security, position within the international community, or patent claims of the United States could be released. The Atomic Energy Act of 1946 established the AEC, which assumed the operations of the Manhattan Project on January 1, 1947, and the rules laid out by the Tolman Committee were incorporated into the AEC Declassification Report.

David Lilienthal, chairman of the newly-established AEC, approached Bacher to serve on the commission in October of 1946, and, although he preferred to return to his lab at Cornell, he accepted the post in order to ensure that a scientist with experience in nuclear physics would be included in the decisions to follow. During his term, Bacher worked exhaustively to assess and restore the various nuclear facilities and stockpiles that had fallen somewhat into disarray after the conclusion of the war, as civilian personnel returned to their peacetime employment and equipment assembled hastily during the conflict degraded over time. This project was of extreme priority to the United States government, which relied upon the strength of the nation’s nuclear stockpile to maintain its position in international discussions. Near the end of his original two-year term, Bacher also found time to assess major non-explosive uses of atomic energy, ultimately advocating for a high-flux reactor to test the durability of materials, a prototype reactor for marine propulsion, and a breeder reactor that could generate more fissile material than it consumes, producing heat for power generation as a byproduct. Although he agreed to a second two-year term in 1948, Bacher left the AEC in May of the following year, and his position on the commission was filled by physicist Henry Smyth. Rather than return to the laboratory he had founded at Cornell, he chose to accept Lee DuBridge’s offer to chair the Division of Physics, Mathematics, and Astronomy at Caltech, and the Bachers arrived in Pasadena in August of 1949.

Letter to Ruth Tolman dated August 12, 1945, describing reactions to the detonation of the atomic bomb in Japan and the end of the Second World War.

These developments in the use and control of atomic energy unfolded within a highly polarized atmosphere that was fraught with political tension in the wake of the Second World War and the beginning of the Cold War. Before the Bachers reached Caltech in 1949, for example, their vacation was interrupted by a call to testify before the Joint Committee on Atomic Energy as to the effectiveness of the leadership of the AEC, especially regarding its chairman, David Lilienthal, who was politically liberal and had been accused in the past of Communist associations. In 1950, when resistance to a new, anti-Communist loyalty oath by the University of California resulted in a faculty crisis at Berkeley, Caltech formed a Committee on Academic Freedom and Tenure to arbitrate in similar cases, and Bacher served two terms as its chairman. In 1951, he also participated in Project Vista, one of several federally-funded “summer studies” undertaken at American universities to develop recommendations for military uses of technology.

Both Bacher and Tolman were highly sensitive to the potentially destructive uses of their scientific achievements during and after the Manhattan Project, and the sometimes precarious interplay of military and civilian scientific goals, funded by federal or private sources, characterized nearly every aspect of the postwar period at Caltech. Nevertheless, both men remained optimistic about the ability of civilized nations to control this new source of energy, as well as possible peacetime applications for the greater good. As Tolman expressed in a 1947 speech given at Brown University:

“It is my faith that the ethical insight and scientific intelligence of man are such that the control of evil is possible. I am sure that humanity will continue to encounter great troubles, but I do not think that civilization will destroy itself. To surmount our troubles, we shall need courage, and patience, and clarity of thought, and sincerity in the advocacy of fair and reasonable courses of action. For these virtues we may pray, each in his own fashion.”