IN MEMORIAM

IN MEMORIAM

Harry Morrison

Professor of Physics, Emeritus

Berkeley

1932—2002

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Our late and beloved colleague, Harry Morrison, was born on October 7, 1932, in Arlington, Virginia, and passed away after a heart attack on January 14, 2002. He joined the Department of Physics at the University of California, Berkeley in July 1969, was promoted to associate professor in 1972, and to full professor in 1977. He was an assistant dean of students from 1985 until his death.

Harry received his Bachelor of Arts degree from the Catholic University in 1955, and his Ph.D. from the same institution in 1960. In the early 1960s, he taught as an assistant professor at the Air Force Academy. From 1965 to 1969, he worked as a theoretical physicist at the Lawrence Livermore National Laboratory, before joining our department.

Harry was the first member of the Berkeley Physics Department from the African-American community, of which he was an intellectual leader and prominent member. He was an especially important role model and intellectual pioneer for the younger generation of black physicists nationally.

At the time of his death, Harry was serving as an assistant dean in the College of Letters and Science, a position that he had occupied since 1985. In that position, he met with undergraduate students to adjudicate student appeals, as well as to support and guide them through all kinds of difficult student situations. His genuine care and concern for students was conspicuous to all who worked with him in that context, and students testified to this through their praise of him for his support and encouragement, and through the fact that again and again they sought him out as the person they would like to see appointed dean. His love for his work with students was so great that he graciously agreed to continue in this position after his retirement in 1994. Fellow deans, college advisors, students, as well as staff members in student services units across campus sadly mourn his passing.

Harry chose as his research area one which was not particularly popular, but which was profound and fundamental, namely, statistical mechanics and the many-body problem. He focused on the relationship between the physics of very small-size objects, such as atoms, namely, "microscopic physics," and that of very large-size objects, such as the universe, that is, "macroscopic physics." In particular, he concentrated on the theory of superfluid helium, to which he devoted most of his research life. He was especially interested in the phenomenon of "spontaneous symmetry breaking" in superfluid helium. This problem concerned how a macroscopic liquid, when cold enough, changes from its classical behavior, like that of water, to very unusual quantum behaviors, such as current flows which can apparently last forever, a kind of "perpetual motion." Physicists call this phenomenon "persistent currents."

Although the phenomenon, which is also known as "spontaneous symmetry-breaking" occurs in liquid helium at extremely cold temperatures, and therefore at very low energies, it turns out to be closely related to the problem of the origin of masses of particles in high energy physics, through the "Higgs mechanism." This is an outstanding example of a profound phenomenon which spans the entire physical world, from the very small to the very large. It was on this problem of connecting the microscopic world of elementary particles with the macroscopic world of superfluids that Harry decided to focus his research.

Harry approached his research with a passionate curiosity, which was contagious for his students and colleagues. He had deep physical insights into the meaning of mathematical structures, and made explicit the many hidden connections between physics and mathematics. Moreover, he was always on the lookout for recent developments in mathematics which could help shed new light on fundamental problems in physics. One important problem which he focused on for many years was how a macroscopic wave-function for a superfluid could emerge, as it were, from nothing except basic symmetry principles.

Perhaps his best known contribution to physics was his demonstration in 1972 of the absence of long-range order in quantum systems in two dimensions, such as in thin superfluid helium films, due to the breaking of a continuous symmetry. This work was done in collaboration with John Garrison and Jack Wong, and it was one of the most successful applications of algebraic quantum field theory to the analysis of physical systems. Their analysis put the earlier work of Hohenberg, Mermin, and Wagner for two-dimensional phase transitions on a firm mathematical footing.

During the late 1970s, Harry applied the theory of "current algebra," developed earlier by Dashen and Sharp for elementary-particle physics, to the geometry of macroscopic quantum flows in superfluid helium. With his students, James Lindesay and Uwe Albertin, he showed that the excitations of the superfluid naturally divided themselves into two types, a longitudinal type, corresponding to "quasi-particles" associated with quantized sound waves, and a transverse type, corresponding to "pseudo-particles" associated with vortices, which are tiny quantum whirlpools in the superfluid. Harry thus established a deep connection between microscopic and macroscopic physics.

In 1980, along with his student Richard Creswick, he further developed the application of current algebra to superfluid helium, and derived the Helmholtz-Onsager equations of motion for vortices for the first time from a microscopic theory. Harry thus continued to develop his interests in the deep connection between microscopic and macroscopic physics.

I believe that in the last few years, in collaboration with his student Achilles Speliotopoulos, he was the first to introduce into physics "sheaf theory," a branch of modern mathematics which deals with certain types of topological structures associated with Riemann surfaces. Using "sheaf theory," he provided a microscopic underpinning for the observed, macroscopic Kosterlitz-Thouless phase transition in thin films of helium, in which helium atoms lose all their frictional resistance to flow against a nearby solid surface only an atomic distance away.

To sum up, Harry's work contributed deeply to our understanding of the profound relationship between microscopic and macroscopic worlds, in particular, to the understanding of the phenomenon of "spontaneous symmetry breaking." The impact of his work may not be apparent today, but should become apparent in this new century, in the emerging field of atomic Bose-Einstein condensates, for which last year's Nobel Prize in physics was awarded, as well as in the well-established field of statistical mechanics.

Everyone who got well acquainted with Harry realized that he was a deep, but unpretentious, scholar. His straightforward, honest, and friendly manner, combined with a keen sense of humor, made him an approachable and warm person, one who was a cherished friend, colleague, adviser, and teacher.

Raymond Chiao

Richard Packard

Kwong-loi Shun