Toshihide Maskawa

Toshihide Maskawa was a highly influential Japanese theoretical physicist. He dedicated his career to understanding the fundamental building blocks of the universe. His most famous work involved explaining a concept known as CP violation. This phenomenon describes a specific type of broken symmetry in nature. In physics, symmetry often means that certain processes look the same even if you change some properties. CP violation shows that nature does not always behave this way. By studying these tiny imbalances, Maskawa helped reveal how the universe is structured at its most basic level.

To understand his discovery, one must look at the Standard Model of particle physics. This model is the framework scientists use to describe how particles interact. In the early 1970s, Maskawa collaborated with physicist Makoto Kobayashi to solve a problem regarding symmetry. They focused on the weak interaction, which is one of the fundamental forces in nature. Their mathematical theory suggested that the symmetry between particles and antiparticles was broken. To make this theory work, they realized that quarks could not exist in just two groups. Instead, their equations required at least three different families, or generations, of quarks to exist. This work resulted in the Cabibbo–Kobayashi–Maskawa matrix. This matrix is a mathematical tool that defines the mixing parameters between different quarks.

This discovery had immediate and profound implications for the field of high energy physics. The prediction made by Maskawa and Kobayashi was not just a mathematical idea. It was a specific claim about the physical makeup of our world. Just four years after their 1973 article was published, experimental evidence appeared. Scientists discovered the bottom quark, which provided the proof that a third generation of quarks actually existed. This validation turned their theoretical work into a cornerstone of modern physics. Their 1973 paper, "CP Violation in the Renormalizable Theory of Weak Interaction," remains incredibly influential. As of 2010, it was ranked as the fourth most cited paper in the history of high energy physics.

Maskawa's academic journey began in Nagoya, Japan. He was born in Nagoya and grew up in the Aichi Prefecture. After World War II, his family worked as sugar wholesalers. He pursued his higher education at Nagoya University, graduating in 1962. He continued his studies there to earn a Ph.D. in particle physics in 1967. His doctoral advisor was the physicist Shoichi Sakata. Beyond his scientific interests, Maskawa was a man of many curiosities. He enjoyed studying mathematics, chemistry, and linguistics. In his youth, he also had a deep love for reading novels, particularly detective stories and the works of Ryūnosuke Akutagawa.

Throughout his long career, Maskawa held many prestigious positions at various Japanese universities. He served as a researcher at Nagoya University and later at Kyoto University. He was also an associate professor at the University of Tokyo. Maskawa held a professorship at the Research Institute of Fundamental Physics, which is now the Yukawa Institute for Theoretical Physics. He served as the director of the Yukawa Institute from 1997 to 2003. Later, he became a special professor and director general of the Kobayashi-Maskawa Institute at Nagoya University. He also held leadership roles at Kyoto Sangyo University.

In 2008, Maskawa reached the highest level of scientific recognition. He was awarded the Nobel Prize in Physics. He shared half of this prize with his collaborator, Makoto Kobayashi. The other half of the prize was awarded to Yoichiro Nambu. The Nobel Committee recognized them for discovering the origin of the broken symmetry that predicts three families of quarks. At the award ceremony held at Stockholm University, Maskawa delivered his Nobel lecture. He spoke in his native Japanese, beginning by telling the audience, "Sorry, I cannot speak English." The international audience was able to follow his deep insights through subtitles on a screen.

Maskawa was also an active participant in social and political discussions. In 2013, he joined chemistry Nobel laureate Hideki Shirakawa to issue a statement against the Japanese State Secrecy Law. He was also known for his support of Article 9 of the Japanese Constitution. His life was marked by many honors, including the Nishina Memorial Prize and the Sakurai Prize. He passed away on July 23, 2021, at the age of 81. He died of oral cancer at his home in Kyoto. His death occurred on the same day as the opening ceremony of the Tokyo Summer Olympic Games.