First Lady of Physics Chien-Shiung Wu

In celebration of Asian American and Pacific Islander Heritage Month, the U.S. Postal Service raises up Dr. Chien-Shiung Wu (1912–1997), one of the most influential nuclear physicists of the 20th century. During a career that spanned more than 40 years, Wu established herself as an authority on conducting precise and accurate research to test fundamental theories of physics. She was honored on a Forever® stamp in 2021.

Born in China, Wu earned her Ph.D. from the University of California, Berkeley, in 1940. She soon went to work for the Division of War Research at Columbia University, where she made invaluable contributions to the experimental process of splitting and harnessing the power of the uranium atom. Post-war, she succeeded in disproving a decades-old, intrinsic element of quantum mechanics: the principle of conservation of parity — which held that objects and their mirror images behave identically, just reversed. Wu considered this her greatest contribution to nuclear physics.