New Delhi: Theoretical physicist Deepak Dhar has been named as the winner of the 2026 Dirac Medal, one of the most prestigious honours in theoretical physics, awarded annually by the International Centre for Theoretical Physics (ICTP) in Trieste, Italy. Instituted in 1985, the medal has previously been awarded to some of the field’s biggest names, including Stephen Hawking.Dhar, the INSA Distinguished Professor at the International Centre for Theoretical Sciences, Bengaluru, is among four physicists honoured this year “for their pioneering contributions to equilibrium statistical mechanics and for extending its concepts and methods into non-equilibrium statistical mechanics, optimisation problems, theoretical neuroscience, and, finally, artificial intelligence,” ICTP mentioned.Statistical mechanics is the branch of physics concerned with how collective behaviour of vast numbers of particles, like grains or neurons, gives rise to large-scale patterns.The others who have been awarded this year are Bernard Derrida, Marc Mézard, and Haim Sompolinsky.Dhar is the second Indian who has received this honour, the first was string theorist Ashoke Sen in 2012.From a small Uttar Pradesh town to California Institute of TechnologyDhar was born in 1951 in Pratapgarh, Uttar Pradesh. While his mother wanted him to become an IAS officer, his father nurtured his scientific curiosity instead, regularly bringing home science magazines, including one called Understanding Science, which Dhar has said shaped his thinking early on.He went on to study at Allahabad University and then IIT Kanpur, before heading to the California Institute of Technology (Caltech) in the US on a Richard Feynman fellowship. There, he worked directly under Richard Feynman as his teaching assistant, completing his PhD in 1978.Decades of work at TIFRDhar joined the Tata Institute of Fundamental Research (TIFR) in Mumbai after returning from California, where he spent most of his career. Later, he worked for nearly eight years as a professor at Indian Institute of Science Education and Research (IISER) Pune, mentoring students and shaping the institution’s physics programme.He is associated with International Centre for Theoretical Sciences, Bengaluru since 2024.His most cited contribution is the Abelian sandpile, developed through his work on sandpile models, a concept that has since become central to the study of complex systems such as earthquakes.Explaining the model, Vasudevan Mukunth wrote in The Hindu, “Imagine dropping grains of sand, one at a time, on a flat surface. The pile slowly grows until it gets steep enough. Then, sometimes new grains on the pile will shift it, maybe cause a modest slide, sometimes even trigger an avalanche. And it is hard to predict in advance which grain will trigger which size of event.”Physicists Per Bak, Chao Tang, and Kurt Wiesenfeld suggested that this “behaviour could be a general principle underlying many phenomena in nature, from earthquakes to forest fires to the extinction of species. They called it self-organised criticality. The term refers to a system that sometimes organises itself into a delicately balanced critical state where even small nudges can produce effects of any size, from trivial to significant,” Mukunth added.Dhar and his collaborators then built the Abelian sandpile model, a mathematical framework capturing the sandpile concept. ‘Abelian’ means no matter in which sequence grains topple and cascade, the pile always settles into the same final shape.“Scientists have used it to model earthquakes, the spread of forest fires, bursts of activity in neural networks in the brain, and fluctuations in financial markets,” The Hindu report added.In 1991, Dhar won the Shanti Swarup Bhatnagar Prize.In 2002, he was awarded the The World Academy of Sciences (TWAS) Award.In 2022, he also became the first Indian to win the Boltzmann Medal, considered the top prize in statistical physics. At the time, he remarked that “I am not the first Indian who has done good work in statistical physics.” He shared the prize with John Hopfield, who was the recipient of Nobel Prize in Physics award in 2014 for laying the foundations of neural networks.A year later, in 2023, the Union government conferred on him the Padma Bhushan, the country’s third-highest civilian award.The Dirac Medal, named after physicist Paul Dirac, is not explicitly given to Nobel laureates, Fields Medallists, or Wolf Prize laureates, though several of its past recipients have gone on to win those honours later.