Farewell Michael Struwe

You came to ETH as an assistant professor in 1986; four years later you became an associate professor before being made a full professor three years after that. What was it like being a young professor in the Department in those days?

Things are certainly very different nowadays. These days assistant professors are assigned a mentor from their own subject area. My mentor back then was Erwin Engeler, a logician – it’s difficult to imagine a subject area that is further away from my own. But it was sort of great, really. I ended up getting to know a very interesting person and I was able to witness the beginnings of logic programming – something that is very important today. Overall, it was a very enriching experience.

All professors had set periods of office back then and a tacit re-election took place after six years. This also applied to assistant professors who were then usually promoted to full professor after a certain amount of time. I, however, was the first assistant professor with a time-limited contract and I had to apply for a full professorship via the regular process later on. But it all went well and I was made a professor.

Which areas of research have you worked in?

My research area, geometric analysis, is extremely rich. There are classical topics such as minimal surfaces, harmonic maps and Riemannian metrics with prescribed curvature, but I also found geometric flows very interesting; for example, the heat flow for harmonic maps.

The proof of the Poincaré conjecture by Grigori Perelman gave the field a real boost because Perelman used methods from geometric analysis for his proof. It had previously been thought that you would primarily need tools from topology, but Perelman’s proof used the Ricci flow – a core part of geometric analysis.

As a lecturer, you were very popular with the students. You won three Golden Owl awards and the Credit Suisse Award for Best Teaching. What was particularly important for you when it came to designing the courses and working with the students?

It was always important to me to also be a good teacher, but I had a lot to learn at the beginning. I studied in Bonn, and some of the professors there had a very idiosyncratic style. I once went to a lecture in algebraic topology where practically every theorem that the lecturer wrote on the board was wrong because he had forgotten some hypothesis. This can of course spur you on to engage with the material yourself, but you need time for that.

Here at ETH, the students have a very busy schedule. They don’t have time to look things up in other sources if they are not properly explained in the lecture. It took me a while to understand that and to take it into account in my teaching. For this, the always constructive feedback from my students was very helpful, but of course you can’t implement it all at once.

It was with the students who started in 2005 that I first felt that everything fell into place, and that was a really exciting moment. It was a great feeling to stand in front of the students in the lecture hall and to work through the material together with them.

Those students then were the ones who gave me my first "Golden Owl", and on top of that the Credit Suisse Award, as well. I can still see myself standing on the stage with my Golden Owl in my hand, wondering who was going to get the prestigious Credit Suisse Award for Best Teaching. There were twelve or fourteen of us from all the different departments, and I was sure someone else was going to win. When they said my name it was such a surprise; I was really touched!

A key moment during your time in the Department was the founding of the Zurich Graduate School in Mathematics (ZGSM), where you also served as director together with Thomas Kappeler from 2009 until your retirement. How did ZGSM come about?

During my time as Head of Department from 2002 to 2004, the founding of ZGSM was one of my priorities. Conveniently, Gisbert Wüstholz was also making efforts in the same direction; he then became the founding director of ZGSM on the side of ETH. Thomas Kappeler was appointed as the director on the side of our partner, the Institute of Mathematics at the University of Zurich. When the initial financing ran out after five years – unfortunately during the financial crisis, of all times – the future of ZGSM was uncertain. There were changes in the board, and Gisbert Wüstholz stepped down as director. At the request of the other board members, I took on his role as director and together with Thomas Kappeler headed up ZGSM from then on until the end of 2019.

At the beginning, our most important task was to secure the funding. That was difficult after 2008 because the Schulleitung of ETH didn’t want to continue to support the project at first. It took patience and persuasion. But when Lino Guzzella took over as Rector, there was a change in the Schulleitung’s attitude towards ZGSM, and since then, also with the new Rector Sarah Springman, the Schulleitung has been very supportive. In fact, when Thomas Kappeler and I were coming to the end of our terms as directors, we were even able to conclude an agreement with Sarah Springman as Rector which we hope will secure the funding of ZGSM for the future.

What were the reasons for the founding of ZGSM and what is its significance today for the Department, ETH, and the University of Zurich?

Before ZGSM was founded, every autumn every member of the faculty would receive numerous requests from people wanting to do their doctoral project with them, and they would have to respond to each request individually. ZGSM made it possible to implement a structured selection process which has served as an important tool for the Department ever since. The applications are collected in a pool and the best candidates are invited for an interview, then the decisions are made collaboratively by the colleagues concerned. This was a big improvement! ZGSM has also been able to help with the funding for incoming doctoral students from abroad. This is one of the central tasks of ZGSM.

Another important task is the co-financing of summer and winter schools and of the "Nachdiplom lectures" in our Department as well as their companion Advanced Graduate Courses at the Institute of Mathematics at the University of Zurich. For these "Nachdiplom lectures", the Department in collaboration with the Institute for Mathematical Research (FIM) usually invites up to three renowned mathematicians each semester to give advanced lecture courses on topics of their choice, with the aim of introducing our doctoral students to a new area of research or of exploring a familiar topic in more detail. We have also created a junior lecturer programme at ZGSM which allows us to co-finance courses taught by postdocs.

On 13 October you will be giving your farewell lecture: “Geometric Analysis – Variations on a Theme”. Will this be your last talk in front of a large audience or do you already have plans in place for the next few years?

Now that we can travel again, I have again been able to accept invitations to speak in various places. In recent weeks I have travelled to Oberwolfach, Rome and Varese, and I was delighted to see some of my colleagues from all over the world in person again. Also for December and for next year I have invitations to conferences, including conferences in Freiburg im Breisgau and in Leipzig, where I will once again have the opportunity to speak in front of a large audience. Of course, I’ll just have to hope that the pandemic doesn’t get in the way!