Roy Glauber (1925-2018).

Roy Glauber, theoretical physicist and recipient of half of the 2005 Nobel Prize in Physics, passed away on 26 December 2018. He was 93. Roy was universally revered as a pioneer of the fields of nuclear scattering and quantum optics. His early elucidation of the quantum mechanical underpinnings of optical coherence formed the basis for advances in laser physics and quantum optics. His optical approximations to high-energy nuclear scattering still serve as the starting point of more detailed analyses of such scattering phenomena. Roy was a child prodigy. In his early years, he made a working reflection telescope and, after learning that the spectra of starlight were key to further understanding stars, a spectrometer. He graduated from the famous Bronx School of Science high school in 1941 at age 16. Although he had originally planned to attend Rensselaer Polytechnic Institute and major in engineering, a full scholarship persuaded him to attend Harvard University instead. His undergraduate years were dramatically altered by the Japanese attack on Pearl Harbor. The faculty began leaving Harvard for wartime positions, and Roy was invited to work on the Manhattan Project, at just 18 years of age. He spent 2 years in Los Alamos in the company of esteemed physicists such as John von Neumann, Enrico Fermi, Niels Bohr, Hans Bethe, and J. Robert Oppenheimer. For the Trinity test (the first nuclear detonation), Roy and some of his young colleagues climbed a nearby mountain in the hopes of seeing the event. They had already begun to pack up, assuming that they had missed it or that it hadn't worked, when the southern sky lit up. The image was indelibly burned into Roy's memory. Roy then returned to Harvard and joined theoretical physicist Julian Schwinger's group. Although he never published with Schwinger, the aspects of coherent mesonpion physics he learned while working with him strongly influenced Roy's later work on the photon coherent state. After earning his bachelor's degree in 1946 and his Ph.D. in 1949, both from Harvard, Roy spent 6 months in Zurich, Switzerland, with the famous theoretical physicist Wolfgang Pauli, and then accepted an invitation from Oppenheimer to work at the Institute for Advanced Study in Princeton, New Jersey. Next, he spent a year researching the electron diffraction of molecules in the Caltech chemistry department under Linus Pauling. There, he developed an accurate approximation of this problem by adapting the more familiar methods of optical diffraction. He realized that his approach to nuclear scattering analysis would become increasingly important as improved particle-accelerator design enabled higher particle energies. He left Caltech to join the faculty at Harvard, where he continued his studies of nuclear scattering over the next decade. The well-known Glauber-eikonal theory of high-energy nuclear scattering that eventually emerged from this work is still used to treat high-energy collisions of heavy nuclei as a probe of their detailed structure. ![][1] PHOTO: STEPHAN SAVOIA/AP PHOTO After the first experiments of Hanbury Brown and Twiss on intensity interferometry in 1954, Roy became interested in the higher-order field correlation functions. He produced a beautiful account of the multiphoton interference phenomena using such correlation functions, which serve as a valuable tool in quantum optics. He also authored an insightful paper on the stochastic dynamics of the kinetic Ising model, which has been used more recently to treat the nonexponential relaxation of linear-chain polymers. In addition to Roy's outstanding physics research, he was an excellent teacher, contributing mightily to the education and understanding of generations of physicists. His 1963 papers on the quantum theory of optical coherence, which earned him the Nobel Prize, were pedagogical masterpieces; they read like a textbook. Committed to his teaching, he rarely missed a class, even on the day he learned that he had won the Nobel. As a fellow of the Texas A&M University Hagler Institute for Advanced Study, he lectured widely in Texas and beyond. Roy was a frequent participant in conferences around the world and a popular keynote speaker at many conference banquets, regaling his fellow attendees with his wry sense of humor, quirky quips, and impressive recall. His sense of humor was on full display at the Ig Nobel awards, a Nobel Prize parody that recognizes achievements in seemingly absurd (ignoble) research. As part of the annual ceremony, paper airplanes are launched en masse toward the stage. For years, Roy gleefully served as “keeper of the broom,” sweeping up the piles of airplanes. S.P. met Roy in 1978 and went on to become his last Ph.D. student. Roy was a demanding and inspirational mentor. A knock on his door would be met with his signature cough, followed by his clarion voice summoning his visitor. He insisted that his students acquire a broad foundation of physics before thinking about research, and he required them to think clearly and express their points with clarity. When researchers suggested that they may have settled on a solution to a question, he would find another important aspect of the problem for them to explore. Roy was rarely persuaded that a manuscript was ready until he had thoroughly vetted it for rigor and clarity, a process that could take months. M.O.S. was fortunate to have Roy as a mentor and friend for his entire career. They often hiked together. On one outing, they encountered a rattlesnake and turned it into a hatband. On another, they saw a school of fish, and Roy joked that the fish obeyed the Poisson statistics of coherent light. Every experience was more fun with Roy. Roy was a dedicated father who raised his children, Jeff and Valerie, as a single parent. He admitted without regret that he had traded some of his scientific research pursuits for the rewards of fatherhood. Roy's partner in later years, Atholie Rosett, accompanied him to Sweden for the Nobel festivities in 2005. We of Roy's extended family regard her affectionately and with much appreciation for making Roy's later years pleasant and productive. Roy retired from Harvard in 2012, took up a position at Texas A&M, and continued to enjoy traveling to conferences around the world. He remained active and lucid to the very end. A veritable giant of modern theoretical physics and a teacher at his very core, he will continue to enrich the lives of generations of physicists and students to come. His legacy as a scientist, educator, father, and friend lives on. [1]: /embed/graphic-1.gif