Willard Frank Libby (1908-1980), a Nobel Prize laureate and Guggenheim Fellowship recipient, was a pioneer in the use of differential decay of the Carbon 14 Isotope for dating organic materials; what we now call radiocarbon dating. He addressed this scientific puzzle after developing a gaseous diffusion enrichment process for uranium-235. His work also involved the identification separation, and control of ‘heavy water’ containing deuterium and tritium, both isotopes of Hydrogen. These processeswere important to the building of the Hiroshima bomb. Through his post-war appointment to the Atomic Energy Commission, he embraced the cause of peaceful nuclear use.
War
He studied chemistry at Berkeley, teaching there until 1941. He worked initially to develop Geiger counters for the detection of background radiation from soils and rock formations; what homeowners call radon gas. His Guggenheim post-doctoral fellowship took him to Princeton, but with the outbreak of WW II hostilities, he was recruited into the Manhattan project at Columbia University, a massive mobilization of top scientists to develop an atomic weapon. Libby’s biography must record his innovation in techniques used for separating and concentrating uranium isotopes through gaseous diffusion.
Peace
Post-war, he taught at the Enrico Fermi Institute at the University of Chicago. He made the connection between the amounts of tritium, an unstable isotope of Hydrogen, in water, and the action of cosmic ray bombardment in the highest levels of the atmosphere. Only trace quantities of tritium are found in any body of water, but once the water is isolated from the atmosphere, it no longer acquires new tritium molecules. This observation led to pioneering techniques for dating water bodies, and identifying different currents of water in the ocean.
This line of research also led him to discover that the bodies of all organisms, whether plants or animals, absorbed trace amounts of the Carbon 14 isotope only during life. He reasoned that the steady radioactive decay of this other unstable isotope could provide a way to measure the time elapsed since death. The technique of documenting the degree of decay of the Carbon isotope, C14, in dead tissues, immediately proved useful. This technology has been immensely helpful to many branches of science, especially archaeology and palaeontology. Its value to science was recognized in the Nobel Prize he received in 1960.
Libby believed fully in the possibilities and promises of atomic science, and carried this message for the Eisenhower administration into the media and on the lecture circuit. Libby’s advocacy for atoms for peace while with the Atomic Energy Commission did, however, put him publicly at odds with some other noted scientists, for example, Linus Pauling, who believed that all testing should cease immediately.
Libby put his belief in the survivability of nuclear attack into practice in the construction of his home fallout shelter, which famously burnt immediately upon completion. His enthusiasm occasionally could lead to nearly laughable mis-steps; for example, he counselled the residents of a rural town with one solitary through-road to flee to the countryside in case of attack. Since this course of action would have been a virtual guarantee of traffic gridlock, and starvation or dehydration would unavoidably await anyone attempting this strategy, his audience took his advice with the proverbial grain of salt.
No such silliness detracts from the facts of his contribution to every discipline that deals with time—radiocarbon dating assures him a place in the pantheon of the greats.
