Sin-Itiro Tomonaga was a Japanese theoretical physicist known for his significant contributions to quantum electrodynamics (QED), a field that studies how light and matter interact. Born on March 31, 1906, he played a crucial role in developing the renormalization technique, which helps to eliminate infinities in calculations related to particle physics. In 1965, Tomonaga was awarded the Nobel Prize in Physics alongside Richard Feynman and Julian Schwinger for their work in QED. His research laid the groundwork for many modern advancements in physics, influencing both theoretical and experimental studies in the field. Tomonaga passed away on July 8, 1979.