In 1934 Harold Urey was awarded the Nobel Prize in chemistry for his discovery of deuterium, an isotope, or species, of hydrogen in which the atoms weigh twice as much as those in ordinary hydrogen. Also known as heavy hydrogen , deuterium became profoundly important to future studies in many scientific fields, including chemistry, physics, and medicine. Urey continued his research on isotopes over the next three decades, and during World War II his experience with deuterium proved invaluable in efforts to separate isotopes of uranium from each other in the development of the first atomic bombs. Later, Urey's research on isotopes also led to a method for determining the earth's atmospheric temperature at various periods in past history. This experimentation has become especially relevant because of concerns about the possibility of global climate change.

Harold Clayton Urey was born in Walkerton, Indiana, on April 29, 1893. His father, Samuel Clayton Urey...