VELTMAN, MARTINUS J.G.

born June 27, 1931, Waalwijk, Neth. Dutch physicist, corecipient with Gerardus 't Hooft of the 1999 Nobel Prize for Physics for their development of a method of mathematically predicting the properties of both the subatomic particles that make up the universe and the fundamental forces through which they interact. Their work led to the discovery of a new subatomic particle, the top quark. In 1963 Veltman received a doctorate in physics at the University of Utrecht and three years later joined the school's faculty. In 1981 he moved to the United States to teach at the University of Michigan, Ann Arbor, where he became professor emeritus in 1997. When Veltman met 't Hooft, who was one of his students at the University of Utrecht, the fundamental theory of particle physics, termed the standard model, was incomplete in that it failed to provide for detailed calculations of physical quantities. In the 1960s Sheldon Glashow, Abdus Salam, and Steven Weinberg had shown theoretically that two of the fundamental forces involved in the model, electromagnetism and the weak nuclear force, could be viewed as manifestations of a single, underlying force, called the electroweak force. A mathematical foundation for the electroweak theory was lacking, however, and in 1969 Veltman and 't Hooft began working to change, or renormalize, it into a workable theory free of nonsensical infinite quantities. With the help of a computer designed by Veltman, the two men provided the needed mathematical basis, which they used to identify the properties of the W and Z particles (massive carriers of the weak force) predicted by the theory. Using the Veltman-'t Hooft model to calculate the physical quantities of other particles, scientists were able to predict the mass of the top quark, which facilitated its direct observation in 1995.