Dr. Reyaz Ahmad
A grain of sand falls. Nothing remarkable happens. Another follows, and then another. Suddenly, one additional grain triggers an avalanche.
Why?
How can countless simple interactions produce behaviour that is complex, unpredictable and yet governed by mathematical structure?
For decades, Professor Deepak Dhar has pursued questions of this kind. On 8 August 2026, that intellectual journey received one of theoretical physics’ major international recognitions when the Abdus Salam International Centre for Theoretical Physics, or ICTP, named him among the four recipients of the 2026 Dirac Medal.
Dhar shares the honour with Bernard Derrida, Marc Mézard and Haim Sompolinsky. ICTP recognised the four scientists for pioneering contributions to statistical mechanics and for extending its concepts into areas including non-equilibrium systems, optimisation, theoretical neuroscience and artificial intelligence.
For India, Dhar’s achievement deserves attention not simply because another Indian scientist has received an international distinction. Its deeper significance lies in the kind of scientific life it celebrates one built on patience, mathematical rigour and the willingness to pursue fundamental questions whose importance may not be immediately visible.
The Scientist Behind the Sandpile
Deepak Dhar was born in Pratapgarh, Uttar Pradesh, in 1951. He completed his B.Sc. at the University of Allahabad in 1970, earned his M.Sc. from IIT Kanpur in 1972 and later received his PhD from the California Institute of Technology. In 1978 he joined the Tata Institute of Fundamental Research, where he spent decades and eventually retired as a Distinguished Professor in 2016. He subsequently worked at IISER Pune and is now an INSA Distinguished Professor at ICTS-TIFR in Bengaluru.
His principal field is statistical physics, which seeks to understand how the collective behaviour of large systems emerges from interactions among many smaller components.
A single molecule tells us little about the temperature of a gas. A single vehicle cannot explain a traffic jam. One neuron cannot explain the behaviour of a brain. Yet when huge numbers of components interact, patterns emerge that are often very different from the behaviour of any single part.
Dhar became internationally known particularly for his work on the Abelian sandpile model and self-organised criticality.
The sandpile offers an elegant way of understanding complexity. Imagine grains being added one by one. Most additions produce little change. Occasionally, however, one grain causes neighbouring grains to move, which cause others to move, and a large avalanche follows.
The remarkable question is not merely why an avalanche happens, but how a system can organise itself into a state in which a tiny disturbance can sometimes produce a very large response.
Dhar’s crucial contribution was to reveal a deep mathematical structure within the Abelian sandpile model. ICTP’s scientific summary notes that he recognised that the model’s “toppling operators” commute, giving its recurrent configurations an Abelian group structure and making the model exactly solvable. His work helped transform an appealing physical picture into a mathematically tractable theory.
That achievement illustrates something profound about science: apparent disorder does not necessarily mean absence of structure.
Sometimes the mathematics is simply waiting to be discovered.
A distinguished scientific journey
The Dirac Medal is not the first major recognition of Dhar’s work. He received the Shanti Swarup Bhatnagar Prize in 1991, the Boltzmann Medal in 2022—becoming the first Indian recipient—and the Padma Bhushan in 2023.
But medals alone do not explain why his career matters.
What is equally significant is that Dhar built much of his scientific career within Indian research institutions. At a time when young researchers sometimes assume that internationally recognised science can emerge only from the great laboratories of Europe or America, his career offers a different lesson.
Scientific excellence depends on ideas, intellectual communities, institutional support, freedom to think and the persistence to remain with difficult problems.
India therefore has reason not merely to celebrate Dhar but to examine the ecosystem that makes researchers of his kind possible.
The legacy behind Dirac Medal
The award itself carries an exceptional scientific heritage.
ICTP established the Dirac Medal in 1985 in honour of Paul Adrien Maurice Dirac, one of the architects of quantum mechanics. It is awarded annually on 8 August, Dirac’s birthday, to scientists who have made significant contributions to theoretical physics. Dirac shared the 1933 Nobel Prize in Physics with Erwin Schrödinger.
There is also a powerful historical link between the medal and the developing world. ICTP founder and Nobel laureate Abdus Salam proposed the institution of the medal. Salam had been Dirac’s student at Cambridge, and ICTP records that hearing Dirac’s lectures influenced his decision to devote his life to research rather than enter the civil service.
The first medallists, in 1985, were Yakov Zeldovich and Edward Witten. Over the years, the medal has recognised many leading theoretical physicists, and several recipients subsequently received Nobel Prizes, Fields Medals or other major honours. The award is not given to those who have already received the Nobel Prize, Fields Medal or Wolf Prize. Dhar now joins this distinguished scientific tradition.
What India should learn from his achievement
There is a larger lesson here.
Modern societies understandably want science to solve urgent problems: energy, climate change, healthcare, agriculture, communication, cybersecurity and artificial intelligence. But the history of science repeatedly demonstrates that transformative applications often emerge from investigations that initially appeared abstract.
Quantum theory was once highly theoretical; it became foundational to semiconductors and modern electronics. Number theory spent centuries as a domain of pure mathematics before becoming central to modern cryptography. Statistical mechanics, developed to understand large collections of particles, now supplies concepts that reach into biology, computation, optimisation and artificial intelligence.
The lesson is not that every abstract investigation will eventually produce a commercial technology. It will not.
The lesson is that a country seeking long-term scientific strength cannot demand immediate utility from every serious scientific question.
India therefore needs universities and research institutes where scholars are encouraged not only to publish, but to think; not merely to follow fashionable subjects, but occasionally to create new ones; not simply to accumulate academic output, but to pursue difficult questions long enough for genuinely original ideas to emerge.
For young Indian scientists, Dhar’s career carries another important message. A researcher does not have to begin with a spectacular problem. What matters is learning to see deeply into an apparently simple one.
A sandpile may look trivial.
In the hands of the right scientific mind, it can reveal principles about complexity itself.
Beyond congratulations
India should certainly congratulate Professor Deepak Dhar. But the most meaningful tribute would go beyond ceremonial praise.
It would mean strengthening laboratories, protecting space for fundamental research, mentoring young scientists, rewarding originality and allowing talented researchers time to think.
It would mean encouraging students in Allahabad, Patna, Kolkata, Bengaluru, Srinagar, Hyderabad, Delhi, Mumbai and hundreds of smaller cities to believe that they too can ask questions worthy of the world’s attention.
Not every scientist will win a Dirac Medal. Nor should medals become the purpose of scientific inquiry. Science advances because human beings remain curious about things they do not yet understand.
Deepak Dhar’s journey reminds us of the extraordinary possibilities contained in that curiosity.
And perhaps no metaphor describes his achievement better than the phenomenon he helped illuminate.
One grain of sand appears insignificant. Yet under the right conditions, a single grain can begin an avalanche.
Deepak Dhar’s Dirac Medal is one man’s distinction. India’s greater challenge is to create the conditions in which his example can become an intellectual avalanche—awakening thousands of young minds to the power of mathematics, curiosity and fundamental science.
(The author is a freelancer and can be reached at [email protected])
