The turning point in Harish-Chandra’s life was when he realised what his true bearings were. Among the most influential abstract mathematicians of the 20th century, it might appear to be strange that he had started off as young enthusiastic physics student. He soon came to realise that what he was truly interested in was the mathematical aspects of physical theories, and not physical intuition in itself, and he eventually changed his professional designation to that of a mathematician.
Born in Kanpur in the year 1923, he matriculated at the University of Allahabad, and was influenced by the great physicist P.A.M. Dirac to study theoretical physics. After a brief stint at the Indian Institute of Science as a research assistant to Homi Bhabha, he moved to Cambridge, where, with Bhabha's recommendation, he was able to become a research student of Dirac, who eventually supervised his PhD . In 1947 he became Dirac's assistant at the Institute for Advanced Study at Princeton. But he soon began to feel that his work lacked mathematical rigor, and this feeling was further solidified by the personality of Dirac; in his own words: "Soon after coming to Princeton I became aware that my work on the Lorentz group was based on somewhat shaky arguments… I once complained to Dirac about the fact that my proofs were not rigorous and he replied, 'I am not interested in proofs but only in what nature does.' This remark confirmed my growing conviction that I did not have the mysterious sixth sense which one needs in order to succeed in physics and I soon decided to move over to mathematics."
An interesting anecdote about a conversation Harish-Chandra had with Freeman Dyson, one of the central figures behind the development of Quantum Electro dynamics. Harish-Chandra had said to him “I am leaving physics for mathematics, I find physics messy and unrigorous, elusive.”Dyson had replied, “I am leaving mathematics for physics for exactly the same reasons.” And so Harish-Chandra began to delve into pure mathematics.
At Princeton he took courses from esteemed mathematicians Emil Artin, Claude Chevalley, and Hermann Weyl. In 1949-50, he spent a year at Harvard to study algebraic geometry with Oscar Zariski. Harish-Chandra then became a professor at Columbia in New York (1950-63) before returning to the Institute for Advanced Study, where he remained for the rest of his life as the IBM-von Neumann Professor of Mathematics. Harish-Chandra’s years at Columbia were his most productive, mathematically, as he concentrated on the discrete series representations of semi-simple Lie groups. He is also known for his work with Armand Borel founding the theory of arithmetic groups. Before changing from physics to mathematics, he had already written a paper on infinit -dimensional representations of semisimple and reductive groups, which were not of much use in physics but had a great deal of significance in mathematics. Despite having some gaps in his mathematical background, he made up for those with his creativity and work-ethic to invent the tools he needed as ‘scaffolding’ for his research,at times unaware that they existed in formal literature. He was among those responsible for transforming infinite-dimensional group representation theory from a topic found on the periphery of mathematics and physics into a major field at the heart of leading-edge mathematics. Eventually, mathematicians moved away from the problem of solving equations to the study of the abstract groups. One problem they faced was to represent abstractly formulated groups by concrete means. With the rise of quantum mechanics infinite groups and matrices had to be considered. To understand very complex interacting systems of highly energetic elementary particles it is necessary to study the group of symmetries that leave the system unchanged. The groups that are most important to this problem are known as simple groups. Harish-Chandra constructed the most fundamental infinite dimensional representations of all of the simple groups and used them to represent generalized functions in these groups by means of Fourier series. Besides high-energy physics, applications of representation theory of simple groups are found in modern number theory and Galois Theory.
"In mathematics we agree that clear thinking is very important, but fuzzy thinking is just as important as clear thinking."
- Prof. Harish chandra
Harish-Chandra once attempted to express his mathematical aesthetics in a painting metaphor, “In mathematics there is an empty canvas before you which can be filled without reference to external reality.” This statement aptly sums up the fundamental aims and nature of pure mathematics. Harish-Chandra, whose health had always been fragile, had his first heart attack in 1969, and from then on his health was a major concern. He suffered a fatal heart attack on October 16, 1983 as he walked in the woods near the Institute. He was considered for the Fields Medal in 1958, but due to internal dissensions among certain mathematicians toward what they termed was ‘Bourbakist’, he was set aside. Nonetheless he was the recipient of the Cole Prize, a Fellow of The Royal Society, and many other honours and accolades.
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