Tolman/Bacher House


Big Science

By the time Richard C. Tolman arrived in Pasadena in 1922, the California Institute of Technology had occupied its current site for just over a decade and had received its present name only two years earlier. Caltech had its beginnings in Throop University, a vocational school founded by Amos G. Throop that was originally located in Old Pasadena. A fruitful partnership with astronomer George E. Hale, as well as a generous land donation from Arthur Fleming, made it possible to expand the campus and move it eastward in 1910.

Newspaper clipping from Pasadena Star News, January 1950: “Caltech Draws Leading Scientists of the World”

With the establishment of Gates Laboratory of Chemistry in 1917, Hale convinced Arthur Amos Noyes, a prominent physical chemist at the Massachusetts Institute of Technology, to move west and take on the development of the fledgling institute. A couple of years later, in 1921, Hale and Noyes brought Robert A. Millikan from Chicago to Caltech to direct the new program in physics and to become the school’s first chief administrator. Hale, Noyes, and Millikan together shaped the early expansion, curriculum, and philosophy of Caltech, quickly turning the small vocational college into a center of scientific achievement.

Millikan saw in Caltech the opportunity to develop a rigorous training program in scientific research, which, to his mind, was too often overlooked at universities in favor of teaching. His drive to establish a scientific center where creativity and critical thinking could stimulate each other became the cornerstone of Caltech’s philosophy under his direction. In 1923, when Millikan received the Nobel Prize in Physics for his prior work on the elementary electronic charge and the photoelectric effect, it would be the first of many achievements to bolster the prestige of the burgeoning university.

Robert Millikan’s Nobel Prize in Physics, Medal, 1923

One of the great talents of Caltech’s three early champions was their ability to attract a variety of high-profile researchers to southern California. Richard C. Tolman, who had worked with Noyes as a graduate student at the Massachusetts Institute of Technology, was one Caltech’s earliest faculty members, accepting a professorship in physical chemistry and mathematical physics in 1922, the same year he joined the National Academy of Sciences. In his lifetime, Tolman was widely regarded as a clear lecturer with a keen physical insight. He published four substantial textbooks during his time at Caltech, two on statistical mechanics and two on relativity and cosmology. He was especially interested in the relationship between statistical mechanics and thermodynamics and in his 1938 monograph, he took quantum, rather than classical, mechanics as a basis for statistical mechanics.

Early in his career, Tolman became interested in relativity, publishing with Gilbert N. Lewis the first American edition of the theory of special relativity in 1909 and a monograph in 1917. His interest surfaced again in the late 1920s, when E. P. Hubble discovered that the amount that various stars are red-shifted correlates with their distance, and the two worked together on a cosmological theory to explain the observations, laying the foundations of the theory of the expanding universe.

Newspaper clipping showing Edwin Hubble and Richard Tolman with a model of the 200-inch Hale Telescope, New York Sun, 6/18/1931.

When Albert Einstein visited Caltech in 1931, 1932, and 1933, he did so largely to spend time with Tolman and a very few others, including Millikan and Paul S. Epstein, who understood and worked on relativity theory. On February 4, 1931, a special dinner at the Athenaeum was held in honor of Einstein’s visit, and Tolman was called upon to act as toastmaster and organize the other speakers. After satirizing Millikan’s organization of the event, which primarily involved volunteering others for various responsibilities, he concluded the story by saying, “That, Fellow Scientists, is the reason why I am toastmaster tonight and the reason why the problem of the entropy of the universe still remains unsolved.”

Richard Tolman and Albert Einstein in 201 E. Bridge Laboratory, 1932.
Speech card from Tolman’s opening remarks at a dinner in honor of Dr. Einstein’s visit to Pasadena, 1931.

While the cosmological theories of Einstein, Hubble, and Tolman were gaining attention in scientific and public circles, efforts to construct a bigger and better telescope were soon underway to test them. Hale received a Rockefeller Foundation grant in 1928 to fund a new observatory and a 200-inch reflecting telescope, the most powerful instrument in existence at the time. The site for the observatory, 100 miles southeast of Pasadena on Palomar Mountain, was chosen in the 1930s to minimize distortion due to light pollution. The mirror, made of Pyrex and cast by Corning Glass Works of New York, was transported to Caltech in 1936 and took 11 years to grind and polish in the Optical Shop on campus. When the telescope saw first light in 1949, the honor of first use was given to Edwin Hubble, whose observational work complemented the theoretical advancements of Einstein, Tolman and others in understanding the nature of the universe.

Dome of the 200-inch Hale Telescope at Palomar Observatory, which was completed in 1948 and saw first light on January 26, 1949.
Aerial photo of the planned Palomar Observatory site with annotations.

Seeing further was not the only goal at Caltech in the 1930s; some dreamed of soaring higher as well. In 1930, Theodore von Kármán, a Hungarian-born physicist and engineer, arrived on campus to lead the new Guggenheim Aeronautical Laboratory (GALCIT). Together with Caltech graduate students Frank Malina, Apollo Smith, Weld Arnold, and Tsien Hsue-shen, as well as Jack Parsons and Edward Forman, von Kármán established a test area in the Arroyo Seco for rocket experiments in 1936. After obtaining military funding for their endeavors and moving across the arroyo to a more permanent site a few years later, this facility was dubbed the Jet Propulsion Laboratory in 1944 and von Kármán became its first director. In 1963, he was the first recipient of the National Medal of Science from President Kennedy.

Portrait of Von Kármán, who became director of the Guggenheim Aeronautical Laboratory at Caltech in 1930 and co-founded Aerojet, a precursor to JPL, in 1936 with Frank Malina and Jack Parsons.

In addition to advances in physics and aeronautics, the early decades at Caltech saw a vast expansion in campus resources and faculty across many disciplines. John P. Buwalda accepted Millikan’s invitation to chair the new Geology Division in 1925, and a Division of the Humanities and Social Sciences was established with William Bennett Munro as its first chairman. The distinguished biologist Thomas Hunt Morgan founded a division of biological sciences in 1928, and Millikan began a visiting-scholars program in the 1930s, which included Einstein’s first trip to Caltech in 1931 as well as visits by Niels Bohr, Paul Dirac, and Erwin Schrödinger, among many others.

The triumvirate formed by Hale, Noyes, and Millikan steered the development of Caltech from its early years through the two World Wars, and many of the core principles of scientific education established under their leadership are still a key part of the Caltech philosophy. In 1946, after Millikan retired from his post as chairman of the Institute, Lee DuBridge became its first President, and another era of rapid expansion and development brought sweeping changes to campus. During DuBridge’s tenure the campus tripled in size and new interdisciplinary fields were opened up for research, including planetary science, geochemistry, and chemical biology.

Among the many new faculty arriving on campus--the number doubled under DuBridge’s direction--was Robert F. Bacher, a nuclear physicist and proven administrator who had headed the bomb physics division of the Manhattan Project at Los Alamos during the Second World War. Soon after the armistice, Bacher worked closely with Richard Tolman and J. Robert Oppenheimer as a U.S. representative on the Scientific and Technical Subcommittee of the United Nations Atomic Energy Commission (UNAEC), developing and assessing the feasibility of plans for nonproliferation and nuclear disarmament. For two years after that, he served as the only scientist on the U.S. Atomic Energy Commission (AEC), which was tasked with assessing the nation’s nuclear facilities and restocking them to face postwar challenges.

Caltech Physics faculty, 1931. Richard Tolman is seated in the front row, two to the right of Albert Einstein, in the center. Robert Bacher, who spent a year at Caltech as a postdoctoral scholar in 1930-1, can be seen standing in the third row, second from the right. He would return to Caltech as the chairman of the Division of Physics, Mathematics, and Astronomy in 1949.

At the end of his AEC term in 1949, rather than return to Cornell University, where he had set up a nuclear physics laboratory before the war and briefly returned afterward to initialize plans for a 300 MeV electron synchrotron, Bacher chose to accept DuBridge’s offer to chair the Division of Physics, Mathematics, and Astronomy (PMA) at Caltech. The Bachers arrived in Pasadena in August of 1949, finding a house to rent on Wilson Avenue just across the street from Caltech.

GE coil fabrication, 1954

Having recently installed a synchrotron at Cornell, Bacher had negotiated as part of his agreement with DuBridge to build a particle accelerator at Caltech and expand the university’s high-energy physics research and personnel. The Caltech Synchrotron would occupy the former Optical Shop on campus, which had recently housed the 200-inch mirror for the Hale Telescope during its grinding and polishing stages and had been vacant since 1948. The immediate availability of the space, in addition to the support of Carl Anderson and Charles Lauritson, who headed the two existing experimental physics projects at Caltech, as well as E. O. Lawrence at the Berkeley Radiation Lab, who offered Bacher the vacuum chamber and magnets from the quarter-scale model of Berkeley’s 6 BeV proton accelerator, allowed for very rapid development of the synchrotron facility. By the summer of 1950 it was in preliminary use, and Phase I of the project was achieved with an electron beam of 500 MeV by 1952. This unprecedented energy allowed the synchrotron group to investigate resonances in the photoproduction of pions and their electromagnetic couplings. In the April, 1950, issue of Caltech’s Engineering & Science, Bacher is quoted as saying, “The purpose of this new accelerator will be to seek additional knowledge of the nature of the forces that hold atomic nuclei together...To obtain a better understanding of these forces is one of the most important goals of present-day physics.” In 1956, its Phase II energy of 1.2 BeV (now GeV is used for gigaelectronvolts rather than BeV) was achieved by raising the magnetic field strength, and the electron beam exceeded 1.5 GeV by 1961.


Robert Bacher and the Caltech Synchrotron group, c.1950s
Bruce Rule, Robert Bacher, Robert Langmuir, and Robert Walker at the Caltech Synchrotron, c.1952.

Throughout this period, the Caltech Synchrotron remained at the forefront of high-energy physics research facilities, but as the energy region available for research expanded, research strategies turned to larger and more powerful machines operated by consortia of universities. In the mid-1960s, Batavia, Illinois, was chosen as the site for the National Accelerator Laboratory, renamed Fermilab in 1974. The Caltech Synchrotron was taken offline in February of 1970, and since that time, the facility has been used as a staging ground for experiments carried out elsewhere.

Charged particle paths captured in a G-5 nuclear emulsion.

Bacher’s expansion of physics at Caltech was not limited to facilities alone; he was also instrumental in putting together the core nuclear physics group that contributed greatly to the university’s legacy throughout the later half of the twentieth century. Just prior to Bacher’s arrival in Pasadena, Charles Lauritsen had already arranged a faculty appointment for Robert Christy. Bacher had worked with him previously at Los Alamos and highly respected him as “a very good theorist,” as he expressed in an oral history interview at Caltech in the early 1980s. His first objective after establishing the Caltech Synchrotron was to move the department toward theoretical work, and he had a plan in mind to accomplish this goal: “The principal start in this direction was getting Feynman out here.” Feynman had gone to Cornell after leaving Los Alamos to work with Hans Bethe, much as Bacher had done a decade earlier. After visiting Caltech to teach a course in the spring of 1950, Feynman agreed to move to Caltech on the condition that he could spend 1950-1951 on sabbatical in Rio de Janeiro at the Brazilian Center for Nuclear Research. A few years later, after visiting Caltech and giving two very impressive lectures, Murray Gell-Mann also joined the faculty in 1955, and the theoretical physics group was off to an auspicious start. Both Feynman and Gell-Mann received Nobel Prizes for their work, Feynman in quantum electrodynamics in 1965 and Gell-Mann for classification of elementary particles and their interactions in 1969.

Letter from Bacher to Richard Feynman dated April 8, 1950, announcing the approval of his appointment as Professor of Theoretical Physics by the Caltech Board of Trustees.
CCover page for the Caltech Synchrotron proposal, 1949.

In 1951, soon after Bacher became chairman of the PMA, Ewen and Purcell discovered the 21 centimeter hydrogen line, caused by radiation emitted at exactly 1420.4 MHz that comes from a transition between two closely-spaced energy levels in the ground state of the neutral hydrogen atom. This discovery hinted at new opportunities to observe interstellar space using radio astronomy, and Bacher immediately decided that Caltech should expand into this new and rapidly developing field. As the co-chair of the observatory committee, Bacher helped to administer both the Mt. Wilson Observatory (owned operated by the Carnegie Institution) and the Palomar Observatory (owned and operated by Caltech). Neither facility was ideally situated to branch into radio astronomy, however, and Bacher was not impressed by an initial suggestion from Carnegie Institution director Vannevar Bush that they build a small 10-foot radio telescope across the street from Caltech in Tournament Park. Backed by DuBridge and a grant from the Office of Naval Research (ONR), he aimed for a more decisive entry into the new field, hiring radio astronomers John Bolton and Gordon Stanley to build the Owens Valley Radio Observatory (OVRO), which was completed in 1958. The two 90-foot dishes, which could be coupled for interferometry, provided a means of locating radio sources that could then be studied at shorter wavelengths at Palomar.

Dedication of the Owens Valley Radio Observatory, one of the world’s largest university-operated radio observatories, on December 19, 1958
Aerial view of the 90-foot radio telescopes, which were completed in 1958 as part of the Owens Valley Radio Observatory.

The Caltech Synchrotron and OVRO projects epitomized an era of big science that required bigger and more elaborate instruments in physics and astronomy, and the efforts of Bacher and DuBridge kept Caltech at the forefront of these innovations. From its early years, newly converted from the Throop College of Technology, to its postwar reorganization and renaissance, Caltech flourished as a hub of scientific research and technological innovation.

Construction of the Owens Valley Radio Telescope (OVRO), 1958.