Harold Urey

Harold Clayton Urey ( YOOR-ee; April 29, 1893 – January 5, 1981) was an American physical chemist who conducted pioneering work on isotopes. He earned the 1934 Nobel Prize in Chemistry "for his discovery of heavy hydrogen." He played a significant role in the development of the atom bomb, as well as contributing to theories on the development of organic life from non-living matter.

Born in Walkerton, Indiana, Urey studied thermodynamics under Gilbert N. Lewis at the University of California, Berkeley. After he received his PhD in 1923, he was awarded a fellowship by the American-Scandinavian Foundation to study at the Niels Bohr Institute in Copenhagen. He was a research associate at Johns Hopkins University from 1924 to 1929, before becoming an associate professor of chemistry at Columbia University. In 1931, he began work with the separation of isotopes that resulted in the discovery of deuterium.

During World War II, Urey turned his knowledge of isotope separation to the problem of uranium enrichment. He headed the group located at Columbia University that developed isotope separation using gaseous diffusion. The method was successfully developed, becoming the sole method used in the early post-war period. After the war, Urey became professor of chemistry at the Institute for Nuclear Studies, and later Ryerson professor of chemistry at the University of Chicago.

Urey speculated the early terrestrial atmosphere was composed of ammonia, methane, and hydrogen. One of his Chicago graduate students was Stanley L. Miller, who showed in the Miller–Urey experiment that if such a mixture were exposed to electric sparks and water, it can interact to produce amino acids, which are among the molecular building blocks of life. Work with isotopes of oxygen led to pioneering the new field of paleoclimatic research. In 1958, he accepted a post as a professor at large at the new University of California, San Diego (UCSD), where he helped create the science faculty. He was one of the founding members of UCSD's school of chemistry created in 1960. He became increasingly interested in space science, and when Apollo 11 returned Moon rock samples from the Moon, Urey examined them at the Lunar Receiving Laboratory. Lunar astronaut Harrison Schmitt said Urey approached him as a volunteer for a one-way mission to the Moon, stating "I will go, and I don't care if I don't come back."