Libby was an authority on radioactivity and radioactive decay. His greatest legacy is the science of radioactive dating, by which the age of ancient organic material can be determined. For this discovery, Libby was awarded the 1960 Nobel Prize in chemistry.

Libby was the son of a farmer. He attended the University of California at Berkeley, earning his bachelor's degree in 1931 and his Ph.D. in 1933. While engaged in his graduate studies, Libby became fascinated with radioactivity. During these years Ernest O. Lawrence (1901-1958) was perfecting his cyclotron particle accelerator at Berkeley. Libby quickly became familiar with nuclear theories and technology and during his doctoral research he constructed the first Geiger counter seen in the United States. The idea of carbon-14 as a means for determining age came to Libby relatively early, particularly after Serge Korff's 1939 experiments showing how radioactive carbon-14 was created in the atmosphere by cosmic rays...