Today in Technology History
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December 17
The man who invented carbon-14 dating, an important tool for studying prehistory, was born 93 years ago.
Willard Frank Libby was born into a farming family on December 17, 1908 in Grand Valley, Colorado. He studied chemistry at Berkeley, earning a Ph.D. in 1933.
During World War II, Libby played a small part in the atomic bomb project by researching isotopes of uranium. (Isotopes are versions of atoms with different numbers of neutrons. They therefore have different atomic weights -- such as uranium-235 and uranium-238.)
Libby then studied an isotope of carbon. Normally, carbon has an atomic weight of 12, but in 1940 scientists isolated carbon-14, an isotope created naturally by cosmic rays hitting our atmosphere. Small amounts of carbon-14 are found in the carbon dioxide in the air -- therefore, all plants and animals incorporate traces of carbon-14 into their bodies as they breathe and eat. After an organism dies, the carbon-14 inside it breaks down.
Since carbon-14 breaks down at a constant rate -- it has a half-life of about 5,730 years -- it is possible to determine very precisely the age of certain old items by examining the amount of carbon-14 in them.
Libby perfected this technique, known as "carbon-14 dating" (or "radiocarbon dating"). It has been enormously useful to geologists, archaeologists and anthropologists. With carbon-14 dating, scientists have learned the age of ancient ruins and artifacts, mummies and monuments. The Shroud of Turin and the Dead Sea Scrolls; Stonehenge and the pyramids; ice ages and the "Iceman" mummy -- all of these have been studied with the carbon-14 technique.
For giving us this invaluable tool, Libby was awarded the 1960 Nobel Prize in chemistry. He died in 1980.
Related links:
Click here to read the lecture awarding Libby his Nobel.
Click here to read about the various techniques used by archaeologists to date ancient objects.
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