Born Dec. 17, 1908, in Grand Valley, Colo. American physical chemist.

Libby received the B. Sc. (1931) and Ph. D. (1933) degrees in chemistry from the University of California at Berkeley, where he later taught chemistry (1933–45). From 1945 to 1959 he worked at the Institute for Nuclear Studies and at the University of Chicago. In 1959 he became a professor of chemistry at the University of California at Los Angeles.

Libby developed the method of radiocarbon dating, which has made it possible to determine the age of archaeological samples (containing carbon) by measuring the radioactivity of the samples caused by the isotope ¹⁴C. He also worked on developing the gaseous-diffusion method of separating the isotope ²³⁵U from natural uranium. He was awarded a Nobel Prize in 1960.