Bryce DeWitt 1923-2004

Bryce DeWitt passed away on 23 September 2004. His life, long dedicated to physics, has left a profound legacy in the theory of gravity (classical and quantum) and in quantum-field theory. He was often far ahead of his time.

DeWitt graduated from Harvard in 1943 and joined the war effort as a navy pilot. He returned to Harvard after the war to do his PhD thesis under the supervision of Julian Schwinger. The subject was nothing less than quantum gravity, and DeWitt's degree was awarded in 1950. He then pursued postdoctoral activities at the Institute for Advanced Study in Princeton, the Swiss Federal Institute of Technology (ETH) in Zurich and a year at the Tata Institute in Bombay.

From 1952 to 1955 he was a senior physicist at Livermore Laboratory in the US. He became an expert in numerical hydrodynamics, which he later applied with his students to the first numerical studies of black-hole collisions, thus inaugurating the field of numerical relativity.

In 1956 DeWitt became director of the Institute of Field Physics at the University of North Carolina. At the university he discovered the properties of Green's functions in curved space-time, which played a major role in his studies of the heat kernel in curved spaces. This had wide-ranging applications in quantum-field theory, general relativity and even mathematics.

In the 1960s DeWitt wrote some monumental works on the analysis of quantum gravity and quantum-gauge theories. He extended the rules that Feynman had found at one-loop in 1961 to all orders, as well as the correct inclusion of the ghosts (also known as Faddeev-Popov ghosts). He also formulated carefully the Wheeler-DeWitt equation that has played an important role in the Hamiltonian understanding of quantum gravity and quantum cosmology.

He was the first also to study the mini-superspace approach to the Friedmann-Robertson-Walker (FRW) cosmology in order to analyse to what extent quantum mechanics can tame the initial singularity. In 1973 DeWitt and his wife, Cecile DeWitt-Morette, moved to the University of Texas.

DeWitt published numerous books and papers, but perhaps the most comprehensive account of his vision is The Global Approach to Quantum Field Theory (CERN Courier April 2004 p40). He was a member of the American Physical Society, the US National Academy of Sciences, and the American Academy of Arts and Sciences. He was awarded the 1987 Dirac Medal of the International Centre for Theoretical Physics, Trieste, jointly with Bruno Zumino, the Marcel Grossmann Prize (with Cecile DeWitt-Morette) in 2000, the Pomeranchuk Prize in 2002, and the Einstein Prize of the American Physical Society in 2004.
Based on an appreciation by Luis Alvarez-Gaume of CERN at the ceremony for the posthumous award of the Einstein Prize in Tampa, Florida, on 17 April 2005.