't Hooft, Gerardus (1946– )

Dutch physicist who with Dutch physicist Martinus Veltman was awarded the Nobel Prize for Physics in 1999 for his work in the determination of the quantum structure of electroweak interactions in physics.

While working as a research student with Martinus Veltman, 't Hooft began studying the problem of renormalizing the non-abelian gauge theory of electroweak interaction. This theory was proposed in the 1960s as a method of uniting the theories of electromagentism and the weak interaction associated with radioactive decay. The theory was successful in predicting the existence of new subatomic particles, but was found to be inaccurate in its predictions of the properties of these particles. The procedure that was required to correct the theory was renormalization, which had been developed in the 1940s by US physicist Richard P Feynman (1965 Nobel prizewinner) and his associates. 'T Hooft succeeded in partially renormalizing the non-abelian gauge theory and, together with Veltman and a computer program the latter had developed, succeeded in completing the task. The modified theory accurately predicted the properties of subatomic particles and predicted the existence of a new particle, which was called the top quark. This particle was discovered in 1995, thus verifying the accuracy of the renormalized theory. Their work has helped advance the field of particle physics by allowing mathematical verification and prediction of experimental results.

'T Hooft was born in Den Helder, the Netherlands. He received his PhD in physics from the University of Utrecht in 1972 and has been a professor of physics there since 1977. He was a guest professor at Boston University, Massachusetts, USA, in 1988 and at Duke University, Durham, North Carolina, in 1989.