When you’re waiting for an elevator at a department store, chances are that several of them are moving away from your floor. When they come closer, multiple elevators arrive without much time between them. Is this a coincidence, or just bad luck? Or perhaps there is some inevitable law of physics hiding beneath?
Sakurako Tanida, an assistant professor in the Nishinari Laboratory at the University of Tokyo’s Research Center for Advanced Science and Technology, is drawn to collective motion, the aggregate movement of a large group of things, and she is taking on the challenge of elucidating this mechanism and determining how it can be useful in everyday life.
Moving from the Natural Sciences II stream to the Department of Physics with an aspiration to study elementary particles
Tanida was a high school student when Yoichiro Nambu, Makoto Kobayashi, and Toshihide Maskawa were awarded the Nobel Prize in Physics.
“When I heard that the Nobel Prize in Physics was awarded for research on elementary particles, I thought it was really cool that a world like that existed so I decided to enter the Department of Physics.”
The Department of Physics requires students to choose a specialty if they want to join the master’s program and Tanida, unsurprisingly, had decided that she would focus on elementary particles. However, she had enrolled as an undergraduate student in the Natural Sciences II stream, where many students advance to the Department of Agriculture or biochemistry departments for their third and fourth years of undergraduate studies.
“The truth is, I didn’t completely understand the difference between the Natural Sciences I and Natural Sciences II streams. It was only after I entered the Natural Sciences II stream that I learned this wasn’t the best route for students who want to enter the Department of Physics,” Tanida explains when looking back on the reason for her choice. “I made a mistake with the stream, but this didn’t mean I wouldn’t be able to enter the Department of Physics. I realized I could do it if I studied hard and didn’t skip classes, so I did just that and it worked.”
It would later become clear that her mistake at the time was not a mistake at all.
Pushing herself but not overdoing it
One week before Tanida was supposed to submit her application to the master’s program and pursue her dream of studying elementary particles, she started to question herself.
“The huge equipment used to do elementary particle experiments are cool but involve working with a large team of 100 to 1000 people, and I felt that I was perhaps more suited for research where I could think carefully on my own or work with just a few people. And when I thought carefully about it, I realized that I really like biology. In undergraduate school, I was impressed when I learned that statistical physics could be used to explain macroscopic mechanisms through microscopic mechanisms, and even after entering the doctoral program, I ended up getting hooked on evolutionary biology for a while.”
These feelings made her realize that she wanted to do research in some shape or form on something organic and on a smaller scale. And at that critical moment, with only one week left until the submission deadline, she changed her choice to a biophysics laboratory. Her friends were quite surprised by this decision.
“I have a lot of interests and tend to push myself to find answers, but I know where to draw the line. I thought biophysics was a perfect fit as it seemed like a field where I could use all kinds of knowledge and it was better to possess various knowledge.”
In the biophysics laboratory, Tanida conducted research to clarify macro-phenomena from micro-mechanisms by using an in vitro system where rodlike protein microtubules glide on a surface covered with motor proteins and collide with each other. She then looked at what patterns emerge when using many microtubules. If we liken the microtubules to organisms, then this can be regarded as an experiment to explain crowd dynamics.
“I have always been interested in states where a lot of things are gathered together. I love Yayoi Kusama’s art abound with circles as I think there’s something beautiful about so many objects collected in one place.”
Tanida had revealed to us that her main interest lies in the aesthetic of aggregates, and she wanted to work in this area while doing something useful for others. This is how she ended up focusing on researching human crowds at the Research Center for Advanced Science and Technology after completing her doctoral degree.
“I have learned how to use physics to elucidate mechanisms and possess the skills to explain them, so I thought I could do something useful by applying my background in some way to crowds. For instance, making dangerous and congested places safer, such as train stations, trains, or large-scale events. Streamlining boarding on airplanes to make operations smoother. I was also thinking about how to maintain social distancing given the current situation surrounding COVID-19.”
Persistence was the key to fate
The synchronization of elevators mentioned at the beginning of this article is what ultimately led Tanida to conduct research on human crowds. Let’s turn back the clock and have her explain the watershed moment in a bit more detail.
“One day when I was a first-year doctoral student, I was waiting for an elevator at a department store in Ikebukuro and noticed that several elevators arrived together. This made me wonder if this was a phenomenon called synchronization, which I had heard of before. After talking to someone who seemed familiar with this phenomenon and looking through research articles, I found that the phenomenon could be explained, but I didn’t feel completely satisfied with the reason why this could be considered synchronization.”
While steadily running experiments for her doctoral research, Tanida began looking into the synchronization of elevators as if it were an independent research project during summer vacation. She took observational notes in front of department store elevators for an hour and a half and she was so immersed that it felt like the main focus of her research instead of something she was doing on the side.
“I had become somewhat obsessed with this and I wanted to continue investigating until I was satisfied with the answer, so I wanted to hear from a professor who was an expert in pedestrian flow.”
This is how Tanida discovered the Nishinari Laboratory, which she is now affiliated with. She contacted Professor Nishinari when she was a doctoral student and asked him what he thought about the phenomenon she had witnessed. This meeting would eventually connect to the research Tanida would do following graduation.
“It will all work out” if you possess both deep and broad knowledge
“You should have two types of knowledge —deep knowledge from thoroughly learning about one thing at a time but also broad knowledge from learning about many things at a surface level. In other words, in addition to having specialized expertise in one area, you should know about a wide range of things as you’ll likely need to change direction in the future from your specialization to something different.”
This is a policy of Professor Nishinari, which Tanida deeply identifies with. She was passionate about elementary particles but “mistakenly” enrolled in the Natural Sciences II stream; although she had entered the Faculty of Science’s Department of Physics, she changed her research focus from elementary particles to biophysics one week before the graduate program application deadline; then she changed her research focus again, this time to people. It may seem as if Tanida has done disparate things, but following this policy has brought her to where she is now. For Tanida, her deep knowledge is being able to explain mechanisms using physics while her broad knowledge of organisms including humans comes from education and natural history.
“From the outside, it may seem like I suddenly changed course, and it differed from what others thought I would do. But I know inside that everything I’ve done has been consistent.”
At first glance, it’s easy to think that Tanida had been sidetracked and taken a detour but when looking back on her journey, her path was a direct one.
However, she didn’t necessarily take this path with confidence.
“Try things you’re interested in. Don’t pay attention to others. I wish I could have told myself these things when I was a master’s student to give me the push I needed. When you start thinking about what to do, concerns may start popping up one after another but just focus on yourself and what you enjoy. Even if you’re worried about something, I think it’s good to put your anxieties aside and just try taking on the challenge.”
Tanida tied up the interview with a powerful note.
“You will be able to find fascinating things if you expand your horizons while remaining committed to your specialty. If you have this perspective, everything will work out in the end.”
※Year of interview:2022
Interview and text: Naoto Horibe
Photography: Junichi Kaizuka