### Public lecture

*(Jointly organised by Department of Physics and Society for Promotion of Science & Technology in India as a part of A Session of Popular Lectures and Interaction)*

Date and time: 11 March 2013 (Monday), 11:30 am

Venue: Auditorium of Dr. S.S. Bhatnagar University Institute of Chemical Engineering & Technology Panjab University, Chandigarh

**Title:** Search for a unified theory

**Speaker:** Prof. Ashoke Sen, Harish-Chandra Research Institute, Allahabad

**About the speaker:** India is proud of Ashoke Sen, a theoretical physicist who has made a number of major original contributions to the subject of string theory, which is a revolutionary and ambitious attempt to build a completely novel unifying substructure, of enormous mathematical sophistication, beneath the field theoretic understanding of the fundamental interactions achieved in the areas of particle physics and gravitation. Prof. Ashoke Sen's enormous mathematical and scientific talents and his consistent dedication to elucidation of the most fundamental aspects of string theory has led him to make repeated breakthroughs in string theory over the last 30 years. Among these are discovery of the relation between equations of motion of massless fields in string theory and string propagation in the background of these massless fields, the link between target space and worldsheet supersymmetries, pioneering work relating strong coupling and weak coupling regimes in string theories – which was seminal to the development of duality symmetries in string theory – and understanding of nonperturbative behaviour in string theory. Prof. Ashoke Sen's work allowed the comprehension of Bekenstein-Hawking entropy of black holes by showing that it followed from counting microscopic states in string theory. The celebrated Sen conjectures concerning the tachyon potential on brane-antibrane systems and non-BPS D-branes in superstring theory and bosonic string theory have motivated new directions of research in string theory. He found novel time dependent solutions of string theory which are used to build cosmological models out of string theory and have led to a new open-closed duality conjecture for string theories. Taken overall, Prof. Sen has made wide ranging and seminal contributions to the architecture of string theory and thus to the revolutions in theoretical physics paradigms during the late 20th and early 21st centuries. Of his nearly 200 research papers, as many as 47 papers have over 100 citations each. In recognition of his contributions, Prof. Sen was awarded the Padma Bhushan in 2013 which followed Padma Shri (2001). The award of one of the first (3 million dollar) Fundamental Physics Prizes (in 2012) to him for his work on string theory, created waves in the world of physics and beyond. He has been a Fellow of the Royal Society since 1998. In 1994 he won the S.S. Bhatnagar award. Other honours conferred on him are the Doctor of Science (Honoris Causa) in 2009 awarded by IIT Kharagpur, the Infosys Prize in the Mathematical Sciences in 2009 and the ICTP Prize in 1989.

**Guest of Honour:** Dr. R. P. Bambah, Professor Emeritus, Formerly Vice-Chancellor, Panjab University

**Chair:** Prof. Arun K. Grover, Vice-Chancellor, Panjab University