Harold C. Urey

Biography

Harold Clayton Urey, born on April 29, 1893, in Walkerton, Indiana, was an American physical chemist who won the 1934 Nobel Prize in Chemistry for discovering heavy hydrogen, known as deuterium. Urey was one of the most influential scientists of the 20th century, contributing significantly to chemistry, nuclear physics, and the study of life's origins. His work went beyond his Nobel-winning discovery, involving uranium enrichment during World War II, studies of ancient climates, and theories about the solar system's formation and life's development on Earth.

Urey's academic journey took him through several top institutions. He completed his undergraduate studies at Earlham College and the University of Montana, then did graduate work at the University of California, Berkeley, studying thermodynamics under Gilbert N. Lewis and earning his PhD in 1923. After his doctorate, he received a fellowship to study at the Niels Bohr Institute in Copenhagen, learning the latest in atomic physics. He worked as a research associate at Johns Hopkins University from 1924 to 1929 before becoming an associate professor of chemistry at Columbia University.

In 1931 at Columbia University, Urey began the isotope separation work that would define his career. He discovered deuterium, an isotope of hydrogen with twice the mass of ordinary hydrogen, opening new paths in both theoretical and applied chemistry. During World War II, Urey used his isotope separation expertise in the Manhattan Project, leading the Columbia University team that developed gaseous diffusion methods for uranium enrichment. This technique became the main method for producing weapons-grade uranium and remained crucial for nuclear technology after the war.

After the war, Urey moved to the University of Chicago, where he expanded his research into cosmochemistry and life's origins. He proposed that Earth's early atmosphere contained reducing gases like ammonia, methane, and hydrogen, leading his graduate student Stanley L. Miller to conduct the famous Miller-Urey experiment in 1953. This experiment showed that organic compounds, including amino acids, could form under early Earth-like conditions when exposed to electrical discharges. Urey's work with oxygen isotopes also advanced paleoclimate research, allowing scientists to estimate ancient temperatures from geological samples. In 1958, he joined the newly formed University of California, San Diego, where he helped build the science faculty and continued his research until he died on January 5, 1981, in La Jolla, California.