Exploring Quantum Gravity Theories and Contributing to the Future
Yasunori Nomura
(Senior Research Scientist, iTHEMS / Director, Berkeley Center for Theoretical Physics, University of California, Berkeley, USA)
Professor Yasunori Nomura, a theoretical physicist at the University of California, Berkeley, has been staying at RIKEN iTHEMS for about two months each summer since last year, conducting research. Despite his busy schedule, Nomura is also actively engaged in outreach activities. We spoke with him about his life journey and thoughts on his research activities.
Keywords: Quantum Gravity, Holographic Principle, Superstring Theory, Theoretical Physics, Cosmology, Outreach
Affiliation and position are as of the interview date: July 2024
Current position: Visiting Scientist, iTHEMS
Main affiliation: Professor, Berkeley Center for Theoretical Physics, University of California, Berkeley, USA
(Written and photographed by Naoko Shinozaki ｰ Freelance Announcer / Mathematics Communicator)
The Path to Becoming a Researcher, Guided by Encounters with People
Nomura, who currently specializes in quantum gravity and cosmology, initially decided to pursue a career as a researcher due to significant encounters with people.
The first major encounter was with his high school physics teacher. This teacher was unique and held an intensive lecture on relativity and quantum mechanics during the summer vacation of his senior year, just before university entrance exams. Although the lecture had little to do with the exams, Nomura was captivated by the allure of physics. “If I hadn’t met that teacher, I wouldn’t be where I am today,” Nomura reflected.
After aspiring to be a physicist, Nomura entered the University of Tokyo, where he met his academic advisor, Professor Tsutomu Yanagida. Through Yanagida-sensei, he became deeply fascinated by particle physics, and Nomura said, “I was blessed with remarkable encounters at key points in my life.”
These pivotal encounters continued. As a graduate student, Nomura had the opportunity to host a postdoctoral researcher from the United States in the group he belonged to. At that time, it was rare to interact with foreign people in Japan, to the extent that just seeing a foreigner on the Yamanote Line and hearing English was considered unusual. Nomura volunteered to show the researcher around Tokyo, and during their travels and meals, they constantly discussed physics. At that time, Nomura had been studying diligently and had gained some confidence in his physics knowledge. However, listening to the researcher, he was astonished by the difference in their levels. Feeling a sense of urgency, Nomura was driven to study even harder, motivated by this encounter.
Later, Nomura learned that this researcher was exceptional, eventually becoming a professor at Harvard University at a young age. In those days before the internet, Nomura did not know much about the world and mistakenly assumed that there were many people like this researcher in America. This misconception became a driving force for Nomura’s growth. Reflecting on it, he chuckled and remarked, "That misunderstanding turned out to be a blessing." What’s more, the researcher had been impressed by Nomura's abilities at the time and marveled, wondering if all Japanese students were at such a high level.
After Nomura graduated from graduate school and applied for positions at universities in the United States, the researcher, who had by then become a professor, wrote a letter of recommendation for him. With additional recommendations from Professor Tsutomu Yanagida and physicist Hitoshi Murayama, Nomura received offers from several American universities, which naturally led him to move to the United States.
The Passion Behind Active Outreach Activities
Now in his 25th year of living in California, Nomura leads an extremely busy life, balancing university lectures, attending meetings, writing grant proposals, reviewing papers, and more. Despite this hectic schedule, he continues his own research, engages in discussions with students, and writes papers.
Additionally, he is deeply involved in outreach activities, such as writing books and appearing on various media platforms. Nomura, who enjoys engaging with people, said that at the core of these activities is a strong desire “to make a larger contribution.” Sometimes, he receives heartwarming feedback like, “I started to love physics after watching the program you appeared on.” “If the younger generation comes to appreciate the charm of physics and research through programs like the one I appeared on, and one day makes a significant discovery, that would be an indirect contribution. There are many ways to contribute to science beyond just research, so I want to engage in various activities comprehensively,” Nomura said.
However, at his core, Nomura remains a physicist. “The reason I’m invited to various media is because I’m a physicist. I always remind myself not to get carried away,” he says. It is likely this humility that allows his thoughts to resonate with and influence so many people.
New Approaches Revealed During the iTHEMS Stay
Nomura, whose passion for research remains undiminished, shared his vision for the future, saying, “I still want to contribute to quantum gravity. I’m looking for what I can do and hope to make my own contributions. In theoretical physics, it’s often the case that significant achievements are made in one’s younger years. It would be great if I could defy that trend.” He also expressed his desire to connect communities in the U.S. and Japan and to achieve results in Japan as well.
During his recent stay at iTHEMS, Nomura said he came up with a new idea. The "holographic principle," which has long been debated among theoretical physicists, has seen progress under certain conditions, but mysteries remain in more general situations. Until now, Nomura had approached this principle using a “bottom-up approach,” building from empirical elements. However, during this stay, he began to think that it might be worth trying a “top-down approach,” viewing the overall picture from higher-level theories such as superstring theory. “Although many of them are in different fields, I have encountered various new ideas and thoughts during this stay that I think might be useful. I don’t know what will come of it, but I feel that the direction of my research might change slightly due to the influence I received at iTHEMS,” Nomura reflects.
Nomura, who finds joy in constantly learning new things and taking on challenges, continues to advance his research, fueled by the belief that “you never know until you try.”