Indian physicist Ashoke Sen became the first Indian to win the 2026 Oskar Klein Medal. He received the award in Stockholm on October 22. ICTS Director Rajesh Gopakumar said, "It has been no less than wonderful having Ashoke with us and setting the tone for excellence here at ICTS."

He received the medal and delivered a lecture titled 'Gravity from strings and strings from gravity' at the AlbaNova University Centre in Stockholm on October 22.

Indian physicist Ashoke Sen has been awarded the 2026 Oskar Klein Medal, becoming the first Indian physicist to receive the honour. Previous recipients include Stephen Hawking, Peter Higgs and Kip Thorne.

Sen, a professor at the International Centre for Theoretical Sciences (ICTS) in Bengaluru, helped show that five string theories once considered separate could be different descriptions of the same underlying theory. String theory seeks to explain matter and the forces of nature within a single framework.

He received the medal and delivered a lecture titled 'Gravity from strings and strings from gravity' in Stockholm on October 22. He discussed how string theory can explain gravity using quantum physics and help answer questions about black holes.

Established in 1988 and named after Swedish theoretical physicist Oskar Klein, the medal is awarded annually by Stockholm University and the Nobel Committee for Physics of the Royal Swedish Academy of Sciences.

Congratulating Sen, ICTS Director Rajesh Gopakumar said, "It has been no less than wonderful having Ashoke with us and setting the tone for excellence here at ICTS."

WHAT HIS RESEARCH SHOWED

String theory proposes that the basic building blocks of matter are tiny strings rather than point-like particles. Different vibrations of a string can appear as different particles.

Sen helped show how a theory describing strong interactions can be equivalent to another describing weak interactions. Other scientists built on this work to connect the five string theories.

His contributions also earned him the Breakthrough Prize in Fundamental Physics in 2012.

The challenge is to find a solution within string theory that matches the particles observed in nature, Sen told India Today.

FROM KOLKATA TO A CAREER IN INDIA

Sen's interest in physics grew through his college and university years. At school, he had been drawn to mathematics. His father taught physics at a college.

"When I was growing up, there were local heroes like Satyendra Nath Bose and Meghnad Saha who everyone in Kolkata knew," he told India Today in a recent interview.

One of his college teachers was physicist Amal Kumar Raychaudhuri. Sen said he first knew him as an excellent teacher and only later learnt of his contributions to physics.

After post-doctoral research in the United States, Sen returned to India. He spent many years at the Harish-Chandra Research Institute in Prayagraj, where he developed much of his work on string theory.

"I never thought of staying abroad, so no motivation needed," he said. "The only deciding factor was that I got a job in India."

Sen, who received the Padma Shri in 2001 and the Padma Bhushan in 2013, works on ideas that may take decades to test. "In subjects like string theory it is even more risky since string theory may not be verified in our lifetime," he said.