1996 CRM-CAP Prize: Professor William J. Unruh
Physics Dept., University of British Columbia

Bill Unruh was born and raised in Winnipeg. He graduated in 1967 with a B.Sc. from the University of Manitoba and received his M.A. and Ph.D. from Princeton University. An NRC Postdoctoral fellowship taken at Birkbeck College, London was followed by a Miller Fellowship at Berkeley. Bill then returned to Canada to teach in the Department of Applied Mathematics at McMaster University. He was recruited by the UBC Physics Department in 1976. Since 1986, he has also been the Director of the Cosmology Program of the Canadian Institute for Advanced Research. Due in large part to his inspirational leadership, this is a very successful program with a high international profile.

Bill is an exceptionally gifted scientist of truly international stature. His contributions to theoretical physics reflect range, versatility and creativity. His work can be categorised under five broad headings: quantum field theory in curved space-times; fundamental basis of quantum mechanics and measurement theory; cosmology; foundations of quantum gravity; and, more recently quantum computers.

He was first internationally recognised for his pioneering work on the quantum radiation from black holes. His 1976 paper on acceleration radiation is universally acknowledged as a landmark in the field. This classic contribution, together with Hawking's simultaneous and complementary discovery that black holes are hot, revealed deep and previously unsuspected interconnections, linking quantum theory, gravity acceleration and thermodynamics. The "Unruh vacuum", the "Unruh temperature" and "Unruh detectors" are phrases used by workers in this field and reflect the importance of his contributions. Currently he has been examining the mechanism of black hole evaporation and particle creation near the horizon by using a hydrodynamic model.

Bill's study of quantum non-demolition measurements have been relevant to the problem of gravitational wave detection, and his explanation (with Zurek) of why "Schrödinger cat states" are not generally observed in macroscopic systems is widely accepted.

He has also been a major influence in the arena of cosmology. In 1985 (with Mazenko and Wald) the "new inflation" theory was shown to be flawed. A paper (with Wald) studied the damping mechanisms for coherent oscillations of axions and put constraints on the observation of these dark-matter candidates. Bill has also made important studies of cosmic strings and made a significant contribution to the debate as to why the cosmological constant is so small.

From the early 1980's to the present, he has thought about quantum gravity and emphasised the crucial role of time. There is a fundamental incompatibility between the current theories of quantum mechanics and general relativity which has to be reconciled in any new theory that seeks to explain the physical world at all levels.

Although he is an expert in theoretical and mathematical physics, Bill is interested in science in general and gets involved with the problems of his experimental colleagues. His fields of interest range from applied subjects such as intercalation batteries to interesting contributions to the American Journal of Physics. Importantly he is also willing to participate in outreach programs from school students. He has served on the Canada Council Killam Selection Committee (1984-88) and was a member of the NSERC Space and Astronomy Committee (1989-92).

His contributions to science have been recognised by many awards and prizes. As an undergraduate he placed in the top 10 of the William Putnam Mathematics Competition (1966) and won First Place in the C.A.P. Undergraduate Examination (1967). He was made a Fellow of the Royal Society of Canada in 1984. Other awards include an Alfred P. Sloan Fellowship (1978-80), the Rutherford Medal from the Royal Society of Canada (1982), the C.A.P. Herzberg Medal (1983), the Steacie Prize (1984), the Steacie Fellowship (1984-86), the B.C. Science Council Distinguished Research (1990). In 1995 he was awarded the C.A.P. Medal of Achievement, and this year he was the recipient of the Canada Council lzaak Walton Killam Memorial Prize in the Natural Sciences.

Bill's many friends and acquaintances in Canada and abroad will share the pleasure of his UBC colleagues in this award. Although he has won other prestigious prizes, this one is special because it represents the appreciation of his talents by his peers in Theoretical and Mathematical Physics.

The above text by Brian G. Turrell (UBC) is taken from Physics in Canada, July/August 1996.