The Nobel Prize in Physics 1999

The last Nobel Prize of the Millenium in Physics has been awarded jointly to Professor Gerardus 't Hooft of the University of Utrecht in Holland and his thesis advisor Professor Emeritus Martinus J.G. Veltman of Holland. According to the Academy's citation, the Nobel Prize has been awarded for 'elucidating the quantum structure of electroweak interaction in Physics'. It further goes on to say that they have placed particle physics theory on a firmer mathematical foundation. In this short note, we will try to understand both these aspects of the award. The work for which they have been awarded the Nobel Prize was done in 1971. However, the precise predictions of properties of particles that were made possible as a result of their work, were tested to a very high degree of accuracy only in this last decade. This was done in a series of measurements in the experiments in the accelerator laboratories at CERN (Geneva) and Fermilab. To understand the full significance of this Nobel Prize, we will have to summarise briefly the developement of our current theoretical framework about the basic constituents of matter and the forces which hold them together. In fact the path can be partially traced in a chain of Nobel prizes starting from one in 1965 to S. Tomonaga, J. Schwinger and R. Feynman, to the one to S.L. Glashow, A. Salam and S. Weinberg in 1979, and then to C. Rubia and Simon van der Meer in 1984 ending with the current one