Arthur Leonard Schawlow

Arthur Leonard Schawlow was born May 5, 1921. Working with Charles Townes, he developed the theoretical foundation for the laser by proposing a resonant cavity using two mirrors to shift maser action from microwaves into visible wavelengths. That 1958 breakthrough made coherent light practical. He then used lasers as precision tools, measuring atomic energy levels with unprecedented accuracy — work that earned him a share of the 1981 Nobel Prize in Physics alongside Nicolaas Bloembergen and Kai Siegbahn. He died April 28, 1999, having seen his mirrors-and-light idea become the engine of everyt…