Robert B. Leighton passed away

I am deeply saddened to tell you that Robert B. Leighton, William L. Valentine Professor of Physics, Emeritus, passed away on the morning of March 9, 1997.

Bob spent his entire scientific career at Caltech and he established a dominating presence in physics and astronomy research and teaching here. His work over the years spanned solid state physics, cosmic ray physics, the beginnings of modern particle physics, solar physics, the planets, infrared astronomy, and millimeter- and submillimeter-wave astronomy. In the latter four fields, his pioneering work opened up entirely new scientific areas of research that subsequently developed into vigorous scientific communities. In addition, he was a renowned teacher, having edited the “The Feynman Lectures in Physics” into their printed form, and authored a highly influential text, “Principles of Modern Physics”, and, for his contemporaries, set a high standard of teaching quality. In addition, he co-authored, with Robbie Vogt, a set of problems to accompany the Feynman Lectures.

In 1948, Leighton's first scientific publication concerned the specific heat of face-centered cubic crystals, but he had already been drawn into Caltech's strong cosmic ray group under Carl Anderson's leadership. He played a key role in 1949 in showing that the mu-meson decay products are two neutrinos and an electron, and he made the first measurement of the energy spectrum of the decay electron (at the time, low statistics experiments suggested that only one neutrino was involved). In 1950 he made the first observation of strange particle decays after the initial discovery of two cases in England in 1947. Over the next seven years, he elucidated many of the properties, e.g., mass, lifetime, decay-modes and energies, of several of the new strange particles, in particular, the lambda, the xi, and what were then called the theta particles (K-mesons).

About 1956, Leighton became interested in the physics of the outer layers of the Sun. With characteristic imagination and insight, he devised Doppler-shift and Zeeman effect solar cameras. They were applied with striking success to the investigation of magnetic and velocity fields on the sun. With the Zeeman camera, Leighton and his students mapped complicated patterns of the sun's magnetic field with excellent resolution. Even more striking were his discoveries of a remarkable five-minute oscillation in local surface velocities and of a “super-granulation pattern” of horizontal convection currents in large cells of moving material. These solar oscillations have subsequently been recognized as internally trapped acoustic waves, opening up the whole new field of solar seismology, subsequently pursued by Ken Libbrecht.

In the early 1960's, Leighton developed and fabricated a novel, inexpensive infrared telescope. He and Gerry Neugebauer used it to produce the first survey of the sky at 2.2 microns. This survey revealed an unexpectedly large number of relatively cool objects. Some of these have been found to be new stars still surrounded by their dusty pre-stellar shells, while others are supergiant stars in the last stages of their evolution, embedded in expanding dusty shells of matter ejected by the stars themselves.

During the middle 1960's Leighton was the Team Leader at JPL for the Imaging Science Investigations on the Mariner 4, 6, and 7 missions to Mars. As Team Leader and an experienced experimental physicist, Leighton played a key role in forming and guiding the development of JPL's first digital television system for use in deep space. He also contributed to the first efforts at image processing and enhancement techniques made possible by the digital form of the imaging data.

In the 1970's, Leighton's interest shifted to the development of large, inexpensive dish antenna which could be used to pursue millimeter-wave interferometry and submillimeter-wave astronomy. Once again, his remarkable experimental abilities opened a new field of science at Caltech which continues to be vigorously pursued at the Owens Valley Radio Observatory (OVRO) and the Caltech Sub-millimeter Observatory (CSO) on Mauna Kea using the “Leighton Dishes”.

Born in Detroit, September 10, 1919, Dr. Leighton received his B.S. in 1941, his M.S. in 1944, and his Ph.D. in 1947, all from Caltech. He continued here as a Research Fellow (1947-1949), Assistant Professor (1949-1953), Associate Professor (1953-1959), Professor (1959-1984), Valentine Professor (1984-1985), and Valentine Professor, Emeritus (1985-1997). Bob served as Division Chair of Physics, Mathematics and Astronomy from 1970 to 1975. He was a member of the American Physical Society, Sigma Xi, the American Astronomical Society, the American Association of Arts and Sciences, and the National Academy of Sciences.

All of us who knew and deeply admired Bob Leighton miss him greatly.

Charles Peck, Caltech