From bomb to the moon: Harold Urey, alum and Nobel laureate of principles

October 14, 2019

Harold Urey at his office in San Diego

Photo: Nobel Laureate and professor, Harold Urey in his office at UC San Diego circa 1965-66. Photo by Ansel Adams, courtesy of the UC RIverside collection.  

Book review: The Life and Science of Harold C. UreyMatthew Shindell, University of Chicago Press (2019)

After witnessing the 1945 Trinity atomic-bomb test, the theoretical physicist J. Robert Oppenheimer recalled Hindu scripture: “Now I am become Death, the destroyer of worlds.” Although this is often interpreted as admitting moral culpability on the part of the Manhattan Project’s scientific director, Oppenheimer remained a central player in the nuclear-weapons establishment until he lost his security clearance in the mid-1950s.

Harold Urey also worked for the Manhattan Project. But by contrast, the Nobel-prize winning chemist distanced himself from nuclear weapons development after the war. His search for science beyond defense work prompted a shift into studying the origins of life and lunar geology. Now, the absorbing biography The Life and Science of Harold C. Urey by science historian Matthew Shindell uses the researcher’s life to show how a conscientious chemist navigated the cold war.

Shindell argues that Urey’s pious upbringing underpinned his convictions about the dangers of a nuclear arms race, and his commitment to research integrity. Urey grew up a minister’s son in a poor Indiana farming family belonging to a plain-living Protestant sect, the Church of the Brethren. Progressing through increasingly diverse educational environments, culminating in a Ph.D. at the University of California, Berkeley, Urey became self-conscious about the zealousness of his family’s faith. He also found the path to a cosmopolitan, middle-class life.

History: Dreaming of the bomb

In the 1920s, Urey was among a small group of chemists who collaborated closely with physicists. Working at Niels Bohr’s Institute for Theoretical Physics at the University of Copenhagen, he kept abreast of developments in quantum mechanics. There, and on travels in Germany, he met the likes of Werner Heisenberg, Wolfgang Pauli and Albert Einstein. But Urey decided he lacked the mathematical skills to make theoretical advances in quantum chemistry. Moving back to the United States, he started both a family and an academic career.

At Johns Hopkins University in Baltimore, Maryland, and later at Columbia University in New York City, Urey taught quantum mechanics to chemists, while setting out on the trail that led him to deuterium. In 1931, he discovered this isotope of hydrogen. Predicted on the basis of work by Bohr, Frederick Soddy, and J. J. Thomson, its existence had been doubted by many chemists and physicists. Urey’s identification won him the Nobel three years later. By this time, he had also co-authored one of the first texts in English on quantum mechanics as applied to molecular systems, the 1930 Atoms, Quanta and Molecules.

Urey’s continuing work on stable isotopes of other chemical elements, such as nitrogen and oxygen, led to important applications in biochemistry and geochemistry, including the pioneering use of isotopic labels to study metabolic pathways. Living in New York also led Urey to political liberalism. He became aware of the anti-Semitism affecting Jewish scientists, and the lack of opportunities for women scientists. A generous mentor, he shared his Nobel prize money with two collaborators, and split a grant he had been awarded with the young Isidor Rabi (who later discovered nuclear magnetic resonance).

Manhattan transfer

The Second World War changed Urey’s life, as it did those of most physical scientists and researchers in many countries. His expertise in isotopes made him valuable to the Manhattan Project. Here, he eventually headed a massive team of scientists and engineers working on the separation of uranium isotopes using gaseous diffusion methods. However, he was ill-suited to the pressure of managing this technologically complex and cumbersome project, and Leslie Groves — the project’s overall director — regarded him with suspicion. Even before the war’s end, Urey became deeply disenchanted with working for the military.

After the war, Urey used his laureate status to voice alarm about the prospect of nuclear warfare. He backed international control through world government as a way to control the military future of atomic energy. This was not a radical view in 1946; it was advanced in the US government’s Report on the International Control of Atomic Energy, much of which had been drafted by Oppenheimer.

Nuclear physics: Arms and the man

However, when the Soviet Union refused this plan for international control, which preserved the US atomic monopoly, advocates of world government found their loyalty as citizens questioned. In 1946, Urey was attacked by J. Parnell Thomas (who would go on to head the House Un-American Activities Committee) for being “one-world-minded”, and not sufficiently patriotic. The FBI also investigated Urey, claiming that he belonged to several communist front organizations.

Over this harrowing period, Urey lost faith in the ability of modern secular society to manage the new threats of the atomic age. Although he had long abandoned his parents’ religion, he began to argue that Judaeo-Christianity was key to democracy. He attributed the success of science itself, with its commitments to honesty and credit, to religious ethics.

In the late 1940s, Urey used his expertise in mass spectrometry to begin work in geochemistry, and then in planetary science. It was a way to escape the orbit of the nuclear weapons establishment (although he still advised the US Atomic Energy Commission). With chemistry graduate Stanley Miller, he tested hypotheses on the origins of life by Soviet biochemist Alexander Oparin and biologist J. B. S. Haldane, and successfully produced amino acids by sparking a solution of water, methane, ammonia and hydrogen. In 1952, Urey published The Planets, a chemical treatise on the formation of the Solar System.

Lunar quest

Urey became influential during the early days of NASA, formed after the 1957 launch of the Soviet satellite Sputnik, offering the agency persuasive reasons to prioritize exploration of the Moon over other bodies. In 1969, he analysed lunar rocks collected during the Apollo 11 mission, which supported his theory of the Moon’s common origin with Earth. He wanted the well-funded agency to test theories about the origins of the Solar System — experimentation beyond the reach of individual university scientists. Despite his influence, he was disappointed in this: NASA focused on crewed space exploration over questions of cosmogony. This last, frustrating chapter of Urey’s life sheds light on the politics of mission-oriented research, in which popular interest or government priorities can take precedence over scientific questions.

Shindell keeps a tight focus on his biographical subject throughout the book. At times, the reader might wish that he had panned out a little more, to sketch the landscape of US cultural life in Urey’s era, or comment on how the space race fitted within the global cold war. But this fine biography wonderfully shows how Urey’s scientific contributions led chemistry in new directions, including to the Moon — and, in depicting the life of a leading scientist, Shindell probes the complex interplay of faith, values and politics in the United States.

Originally published in: Nature 574, 331-332 (2019)