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Carbon Dating

Before the 1940s, scientists had no accurate way of determining the age of fossils or other ancient objects. They had to rely on relative dating techniques, which typically held great potential for error. Then, scientist Willard Frank Libby came up with the method known as radiocarbon dating, a process that revolutionized the way we look at artifacts and document world history.

Libby was born in Grand Valley, Colorado, on December 17, 1908. He enrolled at the University of California at Berkeley in 1927, where he received his B.Sc. and Ph.D. degrees in 1931 and 1933, respectively. In 1933 he accepted an appointment at Berkeley as an instructor in the chemistry department. During the next eight years was promoted to assistant and then associate professor of chemistry. A physical chemist, Libby developed specialties in radiochemistry, particularly hot atom chemistry and tracer techniques.

In 1941 Libby was awarded a Guggenheim Memorial Foundation Fellowship and elected to work at Princeton University. In December of that year, however, the Fellowship was interrupted as the United States entered World War II. Libby went to Columbia University to work on the Manhattan District Project to develop the atomic bomb.

In 1945, after the war had ended, Libby accepted a post of professor of chemistry in the department of chemistry and Institute for Nuclear Studies (now the Enrico Fermi Institute for Nuclear Studies) of Chicago University. There, in 1947, Libby first proposed his radiocarbon dating theories. Soon after, he presented evidence of its viability. Radiocarbon dating, also known as Carbon-14 (or C-14) dating, is based on the principal that all living things are mostly made of carbon. The method of dating lies in trying to determine how much carbon 14 (the unstable, radioactive isotope of carbon) is present in the artifact and comparing it to levels currently present in the atmosphere.

Once an organism dies, the C-14 in the organism begins to disintegrate at a steady, known rate. Thus, scientists can measure the amount of C-14 remaining and use a scientific formula to determine the age of the sample. C-14 dating does have limitations, but it has been very useful in determining the age of some of the worldês most important archaeological finds, including the Dead Sea Scrolls, and the Iceman. The University of Chicago Press published Libby's book, –Radiocarbon Dating,” in 1952. A second edition appeared in 1955. Carbon dating has since become the most important dating method available, placing artifacts in time of up to 50,000 years. The method is applied in many different scientific fields, including archeology, geology, oceanography, hydrology, atmospheric science, and paleoclimatology.

In 1954, Libby was appointed by President Eisenhower as a member of the U.S. Atomic Energy Commission. This appointment was renewed for a further five-year term in 1956, but Libby resigned from it in 1959 to become a professor of chemistry at the University of California at Los Angeles. In 1962, UCLA appointed him director of the Institute of Geophysics and Planetary Physics. In 1962 he became the founding director of UCLA's Space Physics Center. Later he became director of the Douglas Aircraft Company (now part of the Boeing Corp.), and a member of the National Science Foundation's General Commission on Science, the Federal Government and the Academic Institution.

Libby died in 1980, but not before being honored with a Nobel Prize in chemistry in 1960 for his radiocarbon dating method. During the course of his career he also received a number of other awards including the American Chemical Society Award for Nuclear Applications in Chemistry (1956); the Elliott Cresson Medal of the Franklin Institute (1957); the American Chemical Society's Willard Gibbs Medal Award (1958); the Albert Einstein Medal Award (1959); and the Day Medal of the Geological Society of America (1961).

[April 2002]