Deng Yu, 37, won the Fields Medal: It is the most rewarding research that has not been done before.

On July 23, local time, the 2026 International Congress of Mathematicians opened in Philadelphia, USA, and the 2026 was announced on the spot.Fields PrizeWinner, Chinese young mathematicians Deng Yu and Wang Hong both won the prize. The Fields Medal is awarded by the International Mathematics Union and is one of the highest honors in mathematics. It is awarded every four years, with no more than four winners each time, to reward scholars who are under 40 years old and have made outstanding contributions in the field of mathematics.

Previously, the only Chinese mathematicians who won the award were Qiu Chengtong and Tao Zhexuan. Their education and academic training were mainly carried out overseas; Deng Yu and Wang Hong were both undergraduates of Peking University, and their award was regarded as an important moment in Chinese mathematics education.

After the announcement of the Fields Medal, the reporter conducted an exclusive interview with Deng Yu through an online connection. The 37-year-old is currently a tenured professor of mathematics at the University of Chicago.

Reporter:A netizen left a message asking why it took so long to study this topic?

deng yu:Everything we do is an effort to better understand the world. In terms of specific issues, how to go from micro to macro is a very basic question. For me, mathematics is a way to understand the world. I hope to have a better understanding of the world.

The International Mathematical Union recognizes Deng Yu for a series of contributions to the field of partial differential equations, including the rigorous derivation of hard-sphere dynamics from rarefied gases.Boltzmann equation. With this as the key link, he and his collaborators completed the derivation of the macroscopic fluid equation from the movement of microscopic particles, through Boltzmann dynamics, and solved the so-called narrow sense.Hilbert's Sixth Question。

At the International Congress of Mathematicians in Paris in 1900, German mathematician Hilbert posed 23 core outstanding questions. The sixth problem requires the establishment of a rigorous mathematical foundation for physics, and one of the important directions that continue to this day is to explain how macroscopic gas and fluid equations arise from the laws of motion of a large number of microscopic particles. Microscopic dynamics is time-reversible, because tiny particles can return to their original path no matter how they collide, which is reversible; but macroscopic processes are dissipative and directional, such as macroscopic fluids that flow up and go without looking back. There has long been a critical gap in establishing a complete, rigorous mathematical derivation between the two.

Reporter:For more than 120 years, mathematicians have not been able to solve this problem. Why can you make this breakthrough?

deng yu:Since 2018, we have been studying a closely related but different problem for several years. Later, in that problem, we developed a whole set of methods, and I was very satisfied with the results. At the end of 2022, when we discussed with others, we learned that there is such an open problem in particle systems. Then we found that this problem corresponds to what we did before. I believe that this developed method can be used to solve the particle system problem. So in 2023, we will really start to work on this problem.

Reporter:In other words, your research is a natural fit, and there is exactly a matching method to solve this problem?

deng yu:Yes, there is also an element of luck. It is that you happen to encounter such a problem, and the tools developed just before can solve it. In most cases, tools are developed to solve the problem.

At the beginning of 2023, Deng Yu, together with Professor Zahel Hani and Assistant Professor Ma Xiao of the Department of Mathematics of the University of Michigan, formed a three-person team to formally carry out the research on Hilbert's sixth problem in the narrow sense. The cumulant framework and new cutting algorithm developed by them can control the complex collision correlation formed by a large number of particles in the long-term evolution. In March 2025, the trio published a nearly two-hundred-page paper that resolved a long-pending, narrow version of Hilbert's sixth problem.

Reporter:When you find that you can use this set of tools to solve the problem, the heart will be very excited?

deng yu:In terms of mentality, I definitely know that this should be a very good result, and everyone may attach great importance to it. But specifically, after finishing this work, I was really a little exhausted.

Reporter:Why is solving math problems exhausting?

deng yu:Because you have to think about a lot of things. First of all, there is manual labor. More than 100 pages of articles need to be typed word by word. Secondly, you have to think about a lot of things. In the process of proving, how to deduce each step and many details have to be considered. This process is both mental and physical. It took four months to write the article before and after. When the paper was published, it was too tired and did not have the energy to be too excited.

After winning the Fields Medal, Deng Yu entered the public eye, and people noticed that the young mathematician had a wide range of interests. In addition to mathematics, he also likes games, animation, go, poetry. When I was young, I was only one step away from the professional Go track, and I still maintain the habit of playing Go. He also likes poetry, long-term adherence to the creation of old-style poetry.

Reporter:You are not only good at math, but also recite ancient poems and even write ancient poems. What do you like about poetry? It's really far from math.

deng yu:For example, from the perspective of metrical poetry, phonology and rhythm are full of aesthetic feeling. And poetry is also a tool to express inner thoughts. Sometimes write some words, can adjust the mood, change the way of thinking.

Deng Yu was born in Shenzhen in 1989. Under the enlightenment of his parents, he showed his interest and talent in mathematics since childhood. Since 2005, Deng Yu won the gold medal in the National Mathematical Olympiad for middle school students for two consecutive years, and then was selected into the national team of the International Mathematical Olympiad. In July 2006, Deng Yu, who was in his second year of high school, won the gold medal in the International Mathematical Olympiad.

Reporter:When did you realize that you showed far superior mathematical ability to others?

deng yu:When it comes to the International Mathematical Olympiad, there may be dozens of gold medals in the world. I think I can get such a result, whether I am really suitable for the field of mathematics.

Reporter:What changes and influences has this award brought to you?

deng yu:At that time, I felt more clearly that I really wanted to make some achievements in mathematics. Later, when I was studying mathematics, I found that I personally enjoyed learning mathematics.

Reporter:What about enjoying learning math?

deng yu:I learned something and felt a great sense of accomplishment when I was able to solve some problems. In the third year of high school, I didn't have any definite plan. At that time, the school wanted me to participate in the competition for another year, but I felt that I had already participated once and didn't want to repeat it. So nearly a year later, while studying Senior high school other courses, while studying university courses. That year I thought it was good, and it was also a change of direction for me. When I took part in the competition, I paid more attention to number theory. Later, in the third year of high school, I learned a lot about analysis, and then turned to analysis, which had a lot to do with that year.

In 2007, Deng Yu was sent to the School of Mathematical Sciences of Peking University with the gold medal in the International Mathematical Olympiad. In 2009, he transferred to the Department of Mathematics at the Massachusetts Institute of Technology to continue his undergraduate studies.

From Peking University to Massachusetts Institute of Technology, to Princeton University, New York University, University of Southern California, and University of Chicago, Deng Yu spent 16 years gradually focusing on the intersection of partial differential equations, probability, and mathematical physics.

Reporter:You have always studied what you like and what problems you want to solve. Is that the case from the beginning?

deng yu:It has always been that I want to do something, not because it's a major issue.

Reporter:What are your criteria for judging those who are interested and those who are not?

deng yu:If I find a problem very interesting, in terms of my own aesthetics or taste, I think it is a good problem and a good direction, I will naturally consider this aspect.

Reporter:For mathematics researchers, is it hard or fun to think about a problem for a long time?

deng yu:In fact, there are. I think it is more fulfilling for me to do something that no one has done. However, when there is no progress in thinking, you may feel disappointed.

From 2015 to 2018, during his postdoctoral work at the Kurang Institute of New York University, Deng Yu did not make smooth progress on issues of interest to him. Near the stage of job hunting, the realistic pressure brought by academic evaluation and career choice has become concrete for the first time.

Reporter:At that time, a position in the financial industry happened to find you. Have you considered it?

deng yu:I thought about it, because I was not very satisfied with my work at that time, I felt that if there was no way to make better mathematical results, then I might do something else, but later I thought it was OK, so I didn't think about it again.

Reporter:When you pursue the research you are interested in, do you consider real-life factors, such as income, living conditions, and material conditions?

deng yu:Of course it will be considered.

Reporter:At that time, when financial institutions invited you, your income would be much higher than doing research. Why not consider it?

deng yu:Income is not my priority. If I think there is no way to make better math results, I may consider doing something else, but if I can continue to do it, I still hope to continue to do math.

In 2018, Deng Yu finished his postdoctoral work and entered the University of Southern California. It was also from this year that he and Zaher Hani, a professor of mathematics at the University of Michigan, gradually developed a new method in another related problem. A few years later, Ma Xiao joined the cooperation; this set of tools, which grew out of other problems, eventually encountered the sixth problem of Hilbert in the narrow sense.

Reporter:If you can solve such a difficult problem, how much weight do you think talent accounts for in it?

deng yu:Talent is something that determines the lower limit, and effort can raise the upper limit. You need to think seriously and think for a long time, otherwise you can only do something relatively simple. With intelligence, you can do some small things; but some important things, you really need to think about. Chances determine whether you can actually reach your limit. Because most of the time, there is just the right tool, just can notice this problem, just be able to do this problem, and then you can do it, this is a matter of luck.

Reporter:In the process of hard work, will you feel pain, or will you regard these as a way of life?

deng yu:There must be painful times, but this is what I want to do after all, so I am also very happy. When I was an undergraduate, I read a novel in which there was a passage saying that mathematicians are equivalent to the journey of research. Of course, we will also be tired and lose our way, but in spite of this, we are still on the journey and will always explore forward. I think this is very good. There will be smooth and bad times, but when it is not smooth, this is still what we like to do.

After learning that Deng Yu and Wang Hong won the awards, Qiu Chengtong, the first Chinese mathematician to win the Fields Medal, could not hide his excitement. He said in an interview: "I have always expected at least one Chinese mathematician to win the award. Two outstanding young mathematicians won this award." But for Deng Yu, talent, interest, and long thinking brought him here. The Fields Medal is just a sign of his mathematical journey.

Reporter:After receiving the Fields Medal, will your academic status in the industry be greatly improved? What changes will it bring to your subsequent academic career and research topics?

deng yu:Certainly still very important. From my own point of view, this is a very weighty affirmation of my research in recent years, including earlier research. On the other hand, when choosing a problem later, you will have more freedom. You can choose the problem you are interested in at will, and you will feel that you have a sense of guarantee.

Reporter:How do you feel about the results you have accomplished?

deng yu:Whether it is from the mathematical or physical level, it is a very important issue. I feel very honored that we can make a very significant contribution. As for how people will evaluate and treat it in the future, I don't think this is what I am considering now. In short, I am now able to make a pretty good, but also fully able to satisfy their own work. In addition, from a purely mathematical point of view, there is no difference. I will take this award or not, and I will do whatever I am interested in and what I should do next.

Reporter:Will you have new topics and new goals next?

deng yu:There are still many new problems, including the problems of quantum field theory that we are interested in recently, the direction of probability, and the field of partial differential equations. There are also many unsolved problems. I hope that some better results can be made in the future.

Producer Liu Bin Wang Huidong

Reporter Dong Qian