# Indian-American mathematician awarded the Abel Prize

Srinivasa S.R. Varadhan, Courant Institute of Mathematical Sciences, New York, is awarded the Abel Prize for 2007 "for his fundamental contributions to probability theory and in particular for creating a unified theory of large deviations". The announcement was made by the Academy's President, Jan Fridthjof Bernt on 22 March. Kristian Seip, the chair of the Abel committee, gave the reasons for the awarding of the prize. Then Tom Louis Lindstrøm gave a popular science presentation of Varadhan's work.

Probability theory is the mathematical tool for analysing situations governed by chance. The theory of large deviations studies the occurrence of rare events. This subject has concrete applications to fields as diverse as physics, biology, economics, statistics, computer science, and engineering.

Varadhan's theory of large deviations provides a unifying and efficient method for clarifying a rich variety of phenomena arising in complex stochastic systems, in fields as diverse as quantum field theory, statistical physics, population dynamics, econometrics and finance, and traffic engineering. It has also greatly expanded our ability to use computers to simulate and analyse the occurrence of rare events.

Over the last four decades, the theory of large deviations has become a cornerstone of modern probability, both pure and applied. "Varadhan's work has great conceptual strength and ageless beauty. His ideas have been hugely influential and will continue to stimulate further research for a long time", to quote the Abel Committee.

**A well-deserved honour**

When it was announced that Srinivasa S.R. Varadhan was the winner of the Abel Prize 2007, the director of Courant Institute Leslie Greengard was one the first to congratulate Raghu as he is known among friends and colleagues.

"It is wonderful to hear that Raghu Varadhan has been awarded the 2007 Abel Prize. His work is deep, beautiful, and incredibly important, having laid the foundation for much of modern probability theory. Raghu is also one of those rare individuals who work tirelessly on behalf of his students, on behalf of all his colleagues at Courant and NYU, and on behalf of the international mathematics community."