Professor Wu Tai Tsun has made important contributions to a number of subjects in theoretical physics, including the following.
In 1960, he pioneered the study of Bose-Einstein condensation (BEC) through the pair-excitation function when periodic boundary conditions do not apply. In another area of statistical mechanics, Prof Wu realized that the Wiener-Hopf technique can be used to extract information about the asymptotic behavior of various correlation functions in the two-dimensional Ising model of Onsager, both above and below the critical temperature. For these works in statistical mechanics, Prof Wu was awarded the 1999 Dannie Heineman Prize for Mathematical Physics by the American Physical Society, together with Barry McCoy and Zamolodchikov.
Perhaps the most far-reaching work of Prof Wu is on the behavior of scattering cross sections at very high energies. He and Hung Cheng, by applying gauge quantum field theory in a novel way to particle physics, obtained the startling conclusion that the total cross sections, such as those for and , increase without limit at high energies, contrary to the general belief based on Pomeranchuk's theorem. It was several years later when this prediction was experimentally verified.
Prof Wu published a number of papers with Prof C N Yang, one on the analysis of CP violation in the decay, and another on the global formulation of gauge theory. The results in the first paper are still being used today, while the paper on the gauge theory using fiber bundles has led to many recent developments.
Prof Wu has also contributed to a number of other subjects, especially various aspects of electromagnetic theory, and most recently quantum information theory.