New Delhi: As a college student, Deepak Dhar enjoyed solving simple math problems that he found in magazines. Years later, he became one of India’s foremost theoretical physicists, making waves in the field of statistical mechanics.
In an interview with ThePrint, Dhar (71) – whose contributions to theoretical physics have earned him several awards, including the Padma Bhushan this year – says, “Many problems in mathematics are posed in the form of simple puzzles. But sometimes the solutions end up solving deeper problems when you go to solve them.”
“You never know what relevance such solutions can have at the beginning of the journey,” he says. join, “We take Ramanujan’s name and cite him as one of the greatest mathematicians, but his work was not immediately applicable at the time. Even now, there are very few direct technical applications of his work.”
Last year, Dhar became the first Indian scientist to be selected for the Boltzmann Medal, one of the highest international honors in statistical physics awarded once every three years.
In 2002, he was awarded the TWAS (The World Academy of Sciences) Prize – awarded to scientists from developing countries for outstanding contributions to scientific knowledge. he He is also the recipient of the 1991 Shanti Swarup Bhatnagar Prize for Science and Technology – one of the highest Indian science awards – for his contributions to physics.
Currently, he is a Distinguished Professor in the Department of Physics, Indian Institute of Science Education and Research (IISER), Pune.
For Dhar, his journey in statistical mechanics began with his work on intriguing mathematical problems that would be published in the supplemental pages of the journals on Sunday. Dhar says solving puzzles teaches him new mathematical techniques, and leads him to answers to many complex mathematical questions.
His research revolves around understanding how macroscopic properties emerge from large collections of simple objects. For example, how a simple rule determines what happens in a large pile of sand. These simple models are templates for understanding how complex properties appear in everyday objects.
Dhar explains it this way, “Suppose some dry sand is slowly poured on a flat table. We know it will make a conical shaped pile on the table. Now, if you put another grain of sand on it, sometimes that grain will settle down to just one point. Other times, it will slip, knocking over other particles and causing a mini-avalanche.
“If you keep dropping sand one grain at a time, sometimes nothing will happen, while other times the grain will explode and fall down.”
This is a simple example of a system in which a static disturbance is added from outside, but the release or relaxation occurs in jerky bursts,” he says.
Read also: Vidita Vaidya, neuroscientist helping us understand how the brain works under stress
‘TIFR School of Statistical Physics’
While his research often deals with abstract mathematical concepts, Dhar is widely recognized for his rare ability to break down complex concepts into very simple terms.
“Dhar is famous for developing simple methods to obtain exact solutions to many problems in statistical physics,” Srikanth Sastry, a theoretical physicist at the Jawaharlal Nehru Center for Advanced Scientific Research in Bengaluru, tells ThePrint.
“He is also known for training and influencing a large number of students and colleagues in pursuing this style of theoretical statistical physics. He and Professor Mustansir Barma are credited with bringing into existence the ‘TIFR School of Statistical Physics’ and its It is credited with nurturing, as an informal group of people who pursue a certain style of research.
Shastri says that this was not a conscious effort but something that grew out of an environment of excellence resulting from Dhar’s high-quality research.
Spenta Wadia, a theoretical physicist who founded the International Center for Theoretical Sciences at the Tata Institute of Fundamental Research (TIFR) in Mumbai, told ThePrint, “The solution to the sandpile model set the paradigm for the explanation of many natural phenomena Such as magnitude earthquakes and frequency of aftershocks, financial market fluctuations and forest fires etc.
The sandpile model was introduced in a 1987 paper by three physicists, namely Per Buck, Chao Tang and Kurt Wiesenfeld. It was finally settled by Dhar after three years.
Dhar showed that the order in which the grains of sand were placed on the pile did not matter. After the avalanche stopped, the end result was the same. For example, if two grains of sand are added to a static pile in two different orders, first at site A and then at site B, the final pile of sand grains is exactly the same.
“The model had a very interesting solution. And was connected to other problems in statistical mechanics,” says Dhar.
Another mathematical problem that Dhar has been credited with solving is the ‘Direct Sight Animal Enumeration Problem’. Suppose there is a two-dimensional lattice like a square chess board. There is one rule on the board on how chess pieces can be set: if a piece is placed down, the next piece can only be placed in two other adjacent boxes.
In such a set up, how many different shapes can be generated with a finite number of pieces? Dhar had solved this problem.
Mathematical solutions to such problems can also be used to understand the structure of molecules. As Dhar says, “If there is a solution of potassium and sodium chloride and it undergoes crystallization, at what concentration will the sodium and potassium atoms be?”
‘His desk will organize itself in the face of chaos’
Dhar’s colleague, Sreejit Jeeje, associate professor of physics at IISER, told ThePrint, “One thing that stands out about Professor Dhar is that he is very quick. Sometimes I discuss aspects of my work with him. He understands what I want to know even before I ask the question. It’s as if by the time you finish asking your question, he already knows where the problem is, and can often point me in the right direction right away.”
Wadia, who worked with Dhar for nearly thirty years, quipped that his colleague’s desk was always a mess. “Only he would know where to find which paper. Sometimes his wife would come and organize the desk, but soon the desk would ‘organize itself’ into a state of chaos.’
Stating that Dhar had the understanding to express his thoughts precisely, Wadia says, “Even while giving grades, Dhar had a system of giving grades with decimal points. For example he will not just give 8 grade, he will give 8.2 or 8.53.
He also pointed out that Dhar’s teaching style produced excellent students, some of whom are now part of ICTS (International Center for Theoretical Sciences in Bengaluru). His students, says Wadia, have gone on to become some of the most renowned researchers in the field of theoretical physics, recognized globally.
Meanwhile, Dhar says the central government is currently “giving high priority to applied research”, adding that “funding for theoretical research is more difficult to obtain”. Emphasizing the importance of applied work, he warned that it is “wrong” to propagate the idea that “everybody should do only applied work”.
He also remarked that top researchers are asked about the relevance of theoretical research all the time. “Even Michael Faraday was asked this question when he was studying the flow of current through complex circuits and wires,” he says. Dhar explains that at the time, Faraday was chasing some strange phenomenon, but his research became relevant over time as power grids became more complex.
“I think a lot of new ideas in research start with this type of setup, but these ideas can evolve and be used in different areas. I think there’s a mix of relevant and non-relevant research.” There has to be a healthy mix,” he says. Comparing his approach to the discipline of art, he says, “An accounting-minded person may question the use of illustrations, but a broad group of people understand that illustrations are useful in a wide range of contexts.” May be.”
(Editing by Amritansh Arora)
Read also: CERN scientist Archana Sharma working to keep science above politics amid Ukraine war