## Communicating mathematics and the Modellenansatz project: an interview with Gudrun Thäter

### Interview by Francesca Arici and Sema Coskun.

- Born inGermany
- Studied inGermany
- Lives inGermany

### Interview

*Gudrun Thäter is a faculty member at the Karlsruhe Institute of Technology. Besides her scientific work on fluid dynamics, she is one of the initiators of the project Modellansatz, which shows examples through podcasts how mathematicians work and how mathematics is applied. In this interview, she tells us about her research, the Modellansatz and her life. *

**How would you explain your research to a non-specialist?**

I would say I am fortunate in that respect because my field is fluid dynamics. For example, when you put milk in your coffee and stir, you see a nice pattern forming there. This type of processes we have also in process engineering with air conditioning in our cars, or in medical applications. There are so many situations where something is flowing.

Traditionally, we used to do a lot of experiments to understand this better, but experiments are sometimes dangerous and expensive. Since 20 years, more and more simulations have been done numerically and you need a lot of different types of mathematics. For example, you need to derive the right equations and you need to prove that the equations are the right model for the process. You also need to know whether the solutions of the equations are well-behaved, and you can use numerical methods which need regular solutions, otherwise you have to use other methods. To develop numerical methods and test them is also a topic in itself.

This is also a part of mathematics where you are naturally led to work together with engineers, which is the part of my job I like the most.

This is also a part of mathematics where you are naturally led to work together with engineers, which is the part of my job I like the most.

**How did you decide to become a mathematician? What was the motivation behind that you studied mathematics?**

When I was at school my mathematics teacher was sending me to extra classes. At the very first moment, I was like: `So, why is she thinking I need extra training? Am I so bad?` The first time I went there, I immediately understood that she knew that mathematics is much more than what she could teach in school. I always had extra training in mathematics, including special problems which were sent each month to be solved at home and I sent back for feedback. I participated in the mathematics Olympiads every year. There were always brighter people than me, but I knew that this was really something which interested me a lot and was a lot of fun as well.

When I was about to finish school and I had to decide what topic to choose, I was not really sure because I had a lot of different interests and in the end, I was deciding between becoming an opera singer and a mathematician. At that moment, both seemed very natural careers to follow. The decision of becoming a mathematician was more like a decision to avoid a decision because I wasn’t really choosing a profession. When you study mathematics it is absolutely not clear what you will do afterwards. So, in order not to have to make a decision at 18, when I didn’t really know what I would prefer to do, I decided “let’s follow mathematics because anyway it will be interesting. After 5 years I will be much older and then I will know what I want to do”.

**How did the Modellansatz project start?**

The idea was born in the head of my colleague Sebastian Ritterbusch who was listening to podcasts related to engineering and technology. He liked the way you learn a lot about a topic just by listening to interesting conversations. He always tells the story that on the way to a conference in the US he listened to some podcast, and then he attended a lecture by a specialist on the subject. And he had learned more from the podcast than from the specialist: there were questions from the public the specialist could not answer and Sebastian could, because of the podcast. At that moment he understood that this format could be really useful also for learning and teaching. He was looking for someone to work with him and asked me.

I was also a heavy podcast listener and I was listening to podcasts from radio stations. I was a commuter for 10 years during which I started listening to BBC podcasts. Learning while listening to conversations was something I liked a lot.

So we sat down, with minimal equipment, just to try it out. We had a conversation about one of my lectures. After that, we looked at each other and we were like “Yes! We will try that. That feels good.” This was the moment when we decided to start the project.

So we sat down, with minimal equipment, just to try it out. We had a conversation about one of my lectures. After that, we looked at each other and we were like “Yes! We will try that. That feels good.” This was the moment when we decided to start the project.

**How do you select people for the conversations? We notice you often have female mathematicians and mathematicians from minorities. What are the biggest challenges you have faced?**

We stepped into this quite naively. One idea was that there are so many interesting things that our students write for their diploma or master thesis and they end up in a small book in our office and nobody really hears about them. Same for research papers: if we are lucky there might be 15 or 20 people reading them. So, we thought to make applied mathematics available to more than 20 people. At that time we were thinking “We might be able to reach maybe 100. It would be so great” and we felt too optimistic. It took us only two months to have almost 1000 people downloading the episodes and then we were like “Oh there is really a demand, people are really interested in that” which of course gave us a kick to continue.

In between the lines, we had the goal of presenting the female side of mathematics. Being a female mathematician I am attracting a lot of female master thesis students so at the very beginning we had quite a few opportunities for podcasts just by inviting all our students, and there were many women.

I take my recording equipment whenever I am traveling and I am somehow trying to fill the gap of female voices. For example, last year I was in Oxford and London and then I was just going through their staff and got in touch with female mathematicians whose research topic could fit into the scope of our podcast. I wrote six emails and then five of them answered, which is such a wonderful percentage! Three agreed to talk to me on the podcast. Getting to know these people is one of the nice parts of running the project.

Another good thing is that this podcast is an ice-breaker! Very often, after listening to a nice lecture at a conference, I tell the speaker “This was such an interesting lecture. I would like to record a podcast episode with you about that topic. Would you have half an hour for that?” Then I can really talk in depth about this and I don’t feel I am wasting his/her time. That is something completely new for me, late in my career, which I really enjoy doing, also because usually, I am really shy: but, in this way, I can ask mathematicians I don’t know and they often react positively and find the time to talk.

We all have a busy schedule. For me listening to a lecture is good preparation for a meaningful conversation. So, preparing a conversation doesn’t really take me an additional amount of time in preparation.

I always write something as well. At the very beginning, Sebastian and I decided that there should always be something written. We started out with four sentences for each episode, to make it easier for Google to find a podcast semantically. These abstracts got longer and longer. They give additional possibilities, for example also to explain a few specialistic words used in the conversation and not well explained there. And there are always bibliographic references.

**Is there a mathematician you would really like to feature on your podcast?**

Prof. Kulisch, a professor of numerical analysis here in Karlsruhe, who revolutionized the field in the eighties by developing interval arithmetic. I would really like to have a conversation with him but I could not convince him yet and I am not sure why. This is such a pity because it would be probably a very interesting story. I would really like to have him in a podcast.

**Why is it important for you to make mathematics accessible to the general public?**

When I was young, technical knowledge and mathematics were considered something worthwhile, something which helps the advancement of society. I see that somehow this is getting lost. I am not really sure when this started, but facts do not seem to matter anymore. So I wanted to tell more about the interesting things happening in our offices, and how science works in general.

For me, this is as important as my research. With this podcast, I see that I can use my time very effectively and it is paying me back with a lot of interesting experiences. I am learning things which I would not have learned otherwise.

For me, this is as important as my research. With this podcast, I see that I can use my time very effectively and it is paying me back with a lot of interesting experiences. I am learning things which I would not have learned otherwise. This broadens my horizon and gives me a lot of joy because, in the end, we all want to learn more. It makes me happy to see how things are done, not only in my field. And podcasts provide more opportunities also for my teaching. Instead of just hinting at something during a lesson I can tell my students “You can listen to these three episodes if you want to know more about it”.

**So, you also personally learn a lot within this project. What is the biggest and most surprising thing that you have learned in this project?**

There are a lot of things and I just have to remember.

For example, I find it fascinating listening to stories, such as how established mathematicians started, how they ‘fell’ in their field. And if young people listen they can hear that maybe these known mathematicians didn’t really plan to do maths but were pushed by their grandmother. And they can think that they could have a similar career, just following a path by chance, because they want to do something with a friend, and then they start to ‘burn’ for something.

I was at a conference in Oxford in March last year. And I started a conversation with a female colleague. She was 50 and doing her Ph.D. with great passion. She started mathematics when she was over 40, with the support of her daughter and husband. It is so rewarding to listen to that kind of stories. You would never expect that these people exist, and all their energy. It is so wonderful. When I told my colleague Sebastian the story, we thought we should collect parts of these conversations, formal and informal, into a publication: in particular conversations with women because they always have interesting stories to tell.

The other thing which I observed is that women often choose very new topics. Traditionally applied mathematics is connected to mechanical engineering and maybe electrical engineering but, for example, financial mathematics and biomathematics are new and I see a lot of women there. Maybe you could also say that women tend to do biological sciences more than men and if they can apply mathematics there, they are up for it. But I also think that they get more chances in fields where not everything is clear and so settled. So, they can make up their own working field.

And there is also a personal aspect. I have worked in various technical universities. In Germany, they tend to be similar in many ways. Karlsruhe University was one of the first examples; it was founded to study steam engines. In general, technical universities seem very much focused on men who want to become engineers. When I came here to Karlsruhe, one of my stops while trying out different technical universities, for the first time I really felt that in this field women are not that welcome. You cannot really put the finger on a precise behavior, but everything you see is made for a certain type of men, and women are just beginning to enter. There was just one woman professor here in our faculty of stochastics and that was it. Of course, afterwards things became better, but it was really astonishing for me that so late in my career I still could feel so intimidated by my work environment.

I think the podcast project was a possibility to do something very different from what they were used to, which is nevertheless accepted because it is useful for the faculty.

**What are your passions, aside from mathematics?**

Music!

I had to commute for 10 years because you do whatever it takes just to keep going: I was commuting from Paderborn to Bonn, then to Hannover, and then to Dortmund, really long distances. If you survive this, then there is no much space for anything else, maybe just a weekend with your family. When we came here to Karlsruhe and I finally could work where I lived, I had so much time available. I could find interesting music. Karlsruhe is maybe not as vibrant as Berlin or Leipzig but we have quite a few interesting venues with very enthusiastic people inviting the best musicians from all over the world. This was so nice for me that I started writing about my experiences: I joined a blog about concerts; the name is “Konzerttagebuch“. When I joined it already existed for 5 years, now it’s in its 13th year of life.