Wu , Chien-Shiung

(1912–) Chinese–American physicist

One of the world's leading experimental physicists, Wu, who was born in Shanghai, China, gained her BS from the National Central University of China before moving to America in 1936. Here she studied under Ernest O. Lawrence at the University of California, Berkeley. She gained her PhD in 1940, then went on to teach at Smith College, Northampton, Massachusetts, and later at Princeton University. In 1946 she became a staff member at Columbia University, advancing to become professor of physics in 1957.

Her first significant research work was on the mechanism of beta disintegration (in radioactive decay). In particular, she demonstrated in 1956 that the direction of emission of beta rays is strongly correlated with the direction of spin of the emitting nucleus, showing that parity is not conserved in beta disintegration. This experiment confirmed the theories advanced by Tsung Dao Lee of Columbia and Chen Ning Yang of Princeton that in the so-called ‘weak’ nuclear interactions the previously held ‘law of symmetry’ was violated. Yang and Lee later received the Nobel Prize for physics for their theory, and the discovery overturned many central ideas in physics.

In 1958 Richard Feynman and Murray Gell-Mann proposed the theory of conservation of vector current in beta decay. This theory was experimentally confirmed in 1963 by Wu, in collaboration with two other Columbia University physicists.

Wu's other contributions to elementary-particle physics include her demonstration that the electromagnetic radiation from the annihilation of positrons and electrons is polarized – a finding in accordance with Dirac's theory, proving that the electron and positron have opposite parity. She has also undertaken a study of the x-ray spectra of muonic atoms. More recently she has become interested in biological problems, especially the structure of hemoglobin.