National Astronomical Observatory of Japan

Mami Machida

Discoveries from the Past: The value of being able to describe important phenomena in simple ways

Division of Science Associate Professor

Mami Machida

Being able to casually share ideas is one of the privileges of working in the Division of Science.

Since 2020, I have been in the Division of Science, a new department established through the integration of four divisions: the Division of Theoretical Astronomy, the Division of Optical and Infrared Astronomy, the Division of Radio Astronomy, and the Division of Solar and Plasma Astrophysics. Our research involves numerical simulations using supercomputers, such as the K computer, the supercomputer Fugaku, and CfCA’s ATERUI II, sometimes finding discrepancies between theoretically predicted and observationally observed amounts of electromagnetic radiation. One of the privileges of working in the Division of Science is that when we find such disagreements, we can casually share ideas with division members in different fields, such as asking what would happen if we performed observations at optical and radio wavelengths or where we should observe.

Half of my daily work relates to education, such as graduate students supervision, seminars, and journal study groups. Attending group meetings related to my research field is another large part of my job. I am also involved in the International Research Collaboration Center (IRCC), part of the National Institutes of Natural Sciences. Post-doctoral scientists employed there participate in collaborative research projects with scientists at Princeton University and the Max Planck Society, fostering an academic partnership among Japan, the U.S.A, and Europe. My work there contributes to the research community.

Mami Machida during the interview

The excitement when I wonder, “Am I the first one to find this?”

On average, I write one research paper per year, but the one on galaxy cluster magnetic fields published in the journal Nature in May 2021 (note) needed to be written in an exceptionally short time frame. In July of the previous year, Dr. James Chibueze (at that time an associate professor at North-West University), one of the lead authors of the study, informed me that he wanted to submit the paper by October. That meant there were only three months left to finish compiling our data into a submittable form even though nothing but the initial data calibration had been done at that point. So, I even had to ask my students who were just working on their doctoral dissertations, “Could you please help me by analyzing these data?” Alas, what an evil deed I have committed! Our co-authors also include a researcher living in Europe with whom I discussed day after day, asking each other, “What should we do here?” during the day in Europe, which is midnight here in Japan. I continued to work at a super-rapid pace even though I was told, “You should be in bed by now.”

Even in that challenging situation, I couldn’t help but get excited and yell out, “Sugoi-na!” (Awesome!) when I first saw the images from MeerKAT (a radio interferometer operated by the South African Radio Astronomy Observatory). Such a moment, when I wonder, “Am I the first one to find this?” makes me really happy. In other words, without such moments, without that feeling of excitement, I would not be able to write any papers.

Vegetable cultivation and sewing on holidays. My passion is basically creating something.

I joined NAOJ in April 2020, just after the onset of the COVID-19 pandemic. At that time, NAOJ employees were encouraged to work from home. However, a poor internet connection at home did not allow me to do so. To make matters worse, my son’s school was closed at that time, but he was still too young to leave home alone. That was when my coworkers kindly told me that I could bring him to the office because they were all working from home. That was a huge help to me. These doodles and scribbles were all drawn by my son. When I delivered him, I was serving as an assistant professor at Kyushu University, where I took maternity and childcare leave for six months. Considering that I had to ask other faculty members to cover my classes and needed to supervise students writing papers, I took a rather long leave of absence for a faculty member at a university. Taking an extended leave of absence needs cooperation from various individuals. In that respect, NAOJ creates an atmosphere where employees feel free to take parental leave. This is why NAOJ has many “ikumen” employees who intend to take parental leave. (“Ikumen” is a Japanese slang word for a man who takes an interest in child rearing.)

Because my son once told me that he wanted to cultivate vegetables, I currently rent a plot of land to cultivate various crops that are easy to grow, such as potatoes and peanuts. My hobbies also include baking and sewing. When on parental leave, I made many sewn items, including clothes and bags, for my baby. After he started school, I sewed an arts-and-crafts bag, a music bag, and many other bags such as he needed for school. As it turned out, creating something, or giving shape to something, seems to be my passion.

Whiteboard filled with her son’s scribbles.
Mami Machida during the interview.

Finding important phenomena that can be explained by simple assumptions

When I was a child, I used to find it strange that Pluto alone has an inclined orbit among the planets, wondering why only this one deviates from the others. So, Pluto’s demotion from planet status at the 2006 IAU General Assembly satisfied me that everything fell into place. I felt, “I thought so!” When I was in high school, I was part of an astronomy club, but one reason I decided to pursue STEM in university was actually my poor English ability. However, linguistic abilities turned out to be must-haves: attending conferences and writing papers both require English skills. Even describing complex things in simple words requires high proficiency in your native language. We tend to describe every single detail when explaining something, but what we should do is ignore minor details and focus only on the things that really matter. That kind of simplicity is most clearly seen in Nature, where the length of articles is set to be as short as possible and only a limited number of images are allowed.

I think that simplicity is underappreciated. In the course of my research, I have been trying to find important phenomena that have gone unnoticed, particularly ones that can be explained by the simplest assumptions possible. With recent advances in observations and theories, scientific studies tend to delve deeper into details by incorporating complex concepts such as neutrinos. I take the opposite approach, looking for something like a phenomenon that was observed 50 years ago but is still in the new discovery stage where its average properties are expressed as simple approximations.

Mami Machida posing in front of her laboratory.

Interview Date: July 19, 2022 / Published: November 25, 2022
Interview & Article: Masami Usuda / Translation: Ryo Sato and Ramsey Lundock / Photo: Shogo Nagayama
With a few exceptions, the contents of this article are as of the interview date.