During the Sino-Japanese war Professor Wu taught in the physics department at the National Southwest Associated University in Kunming ( 昆明 ). He went to the USA again in 1946 and taught (1946-1949) at the University of Michigan and Columbia University. From 1949-1963 he was Head of the Theoretical Division of the Physics Institute of the National Research Council of Canada. From 1963 to 1978 he taught successively at the New York Polytechnical Institute and at SUNY-Buffalo. He retired from the latter in 1978 and moved to Taiwan. He came out of retirement in 1983 and for the next eleven years, 1983 to 1994, as President of Academia Sinica in Taipei, led the Academy through a phase of rapd expansion and upgrading of research quality.

It is not possible for me to detail all the important contributions of Professor Wu in his long career. I shall concentrate only on some aspects of his contribution to physics and on his influence on physicists.

Professor Wu's research in physics covers a wide range, including almost all the areas of modern theoretical physics: molecular physics, atomic physics, nuclear physics, plasma physics, scattering theory, statistical physics, astrophysics and atmospheric physics. He has published ten monographs, over one hundred technical articles and seven textbooks for graduate students. I cannot discuss here in detail Professor Wu's work in all these areas. I shall thus go into only a couple of items.

Professor Wu's Ph.D. thesis work was done during the year 1932 to 1933 on a subject that he had found for himself: In the periodic table of elements where the 5f shell is being filled up, he believed, there may start a new series of 14 elements, similar in their chemical properties - a situation analogous to the series of rare-earth elements. He wanted to investigate if, and at what Z, this "second rare-earth series" may begin. To think of such a problem shows maturity, taste and good physical insight on the part of the young graduate student. Technically its solution required a proper treatment of a double well potential which Wu successfully found, again by himself.

The work was published first in a short letter and then a full paper:
Ta-You Wu and S. Goudsmit, Physical Review, 43, 496 (1933),
Ta-You Wu, Physical Review, 44, 727 (1933).

Wu's result was that near Uranium (Z=92) there will start the second rare-earth series. Unfortunately few physicists and chemists were interested in elements heavier than Uranium in those years. Thus the paper did not attract much attention. After the discovery of the phenomena of fission, transuranium elements became a hot topic, starting around 1940. To find their chemical properties, i.e. their positions in the periodic table, thus became a very important theoretical topic.

In 1941, M. G. Mayer (1906-1972, Nobel physics prize winner of 1963), at the suggestion of Fermi, made a calculation which was essentially the same as Wu's, arriving at essentially the same conclusions [Physical Review, 60, 184 (1941).]. She evidently did not know about Wu's work of 1933. It was only after her paper's publication that someone pointed out to her the earlier papers of Wu.

After Professor Wu returned to China in 1934, he taught first in Peking University and then during the wartime in the National Southwest Associated University, altogether for twelve years. Hundreds of students had taken his courses in these years. He also guided many in their research. Among his colleagues and students the following had done research work with him: H. C. Cheng ( 鄭華熾 ), C. F. Hsueh ( 薛琴舫 ), A. T. Kiang ( 江安才 ), S. T. Ma ( 馬仕俊 ), S. T. Shen ( 沈壽春 ), Kun Huang ( 黃昆 ), C. N. Yang ( 楊振寧 ), and others. In 1946 he specially selected two students, K. Y. Chu ( 朱光亞 ) and T. D. Lee ( 李政道 ), to go to the USA with him for graduate education, a move of great importance to these two who later became famous physicists.

Professor Wu is the third Chinese to have received a Ph.D. in theoretical physics. Before him there were S. C. Wang (王守競, 1927 Ph.D. at Columbia University) and P. Y. Chou (周培原, 1928 Ph.D. at Cal. Tech.). Professor Wang taught at Zhejiang University and Peking University for short periods after returning to China. He then entered into government service. Professor Chou (in Pin-yin, Zhou), after returning to China, taught at Tsinghua University, National Southwest Associated University, then Peking University. He was the one who introduced the research areas of general relativity and hydrodynamics into China.

Professor Wu was the one who introduced to hundreds of Chinese students and research workers quantum mechanics. As we all know quantum mechanics not only revolutionized physics and chemistry, it also created new industries. The semiconductor, computer, laser and information industries were not possible without quantum mechanics. Students of Professor Wu, and their students, played essential roles in all of these academic and industrial developments in China in the last sixty years.

The eight years of Sino-Japanese war was a very difficult period for everyone in Kunming. To add to Professor Wu's problems was the fact that Mrs. Wu was not well and needed constant bedside care. Under such difficult circumstances, Professor Wu wrote during 1938 to 1939 an authoritative monograph: Vibrational Spectra and Structure of Polyatomic Molecules, which was published in Shanghai. This book became an encyclopedia of the field. When in 1946 Edwards Publisher reprinted a number of important monographs on various topics in physics (including e.g. Pauli's long article of 1933 in the Handbuch der Physik), Wu's book was one of them.

In his distinguished academic career professor Wu has influenced many physicists of several generations and has left his imprint on several institutes in mainland China, the USA, Canada and Taiwan. I shall not further detail these, but please allow me to recall two events from my personal life.

In the spring of 1942, I was a senior at the National Southwest Associated University in Kunming. To find a topic for my B.Sc. degree thesis, I went to Professor Wu. He agreed to oversee my thesis and introduced me to the relationship between symmetry principle in physics and group theory. This introduction was of determining importance to my later career. On October 31, 1957, upon learning that I was going to receive, together with T. D. Lee, that year's Nobel Prize, I wrote a letter to Professor Wu. That letter and his response are reprinted below as Figures 1 and 2.