Radiocarbon Dating Testing
Radiocarbon dating is one of the most significant scientific advancements of the 20th century, for which its inventor was awarded the Nobel Prize. Using this method of dating ancient artifacts, researchers have estimated the time of the writing of the Dead Sea Scrolls and the construction of Stonehenge, among numerous other historical discoveries. While radiocarbon dating has its problems and limitations, it is a method that will continue to aid historical research of the future.
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History
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Professor Willard F. Libby at the University of Chicago developed radiocarbon dating just after World War II. In the 1950s, nuclear testing rendered the method inaccurate, as nuclear contamination modified the results, but this led to the development of alternative radiocarbon dating methods that provided a higher rate of accuracy. It was the first method of accurately dating ancient artifacts. In 1960, Libby earned the Nobel Prize in Chemistry for this development.
Method
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Radiocarbon dating is a method used to test any material made up of carbon. All plants, herbivores, and creatures that eat herbivores possess the same percentage of carbon-14 as exists in the surrounding atmosphere. As the Public Broadcasting Service explains, once these plants or animals die, their carbon-14 begins to decay into nitrogen-14. Carbon-14 has a half-life of 5,730 years, meaning it takes 5,730 years for carbon-14 to decay by half. With this number as a reference, researchers can determine the date of an object by calculating how much carbon-14 is left in it.
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Examples
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Radiocarbon dating has helped researchers calculate the age of several well-known artifacts. At the University of Arizona in 1994, researchers used radiocarbon dating to determine the age of the Dead Sea Scrolls, which dated back to between 1 and 200 B.C. In 2008, Professors Tim Darvill and Geoff Wainwright at Bournemouth University in England dug up material from Stonehenge and sent it to Oxford University for radiocarbon dating, which dated the construction of Stonehenge to 2300 B.C.
Problems
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Radiocarbon dating is accurate to within 50 years, but only when the artifact has not been contaminated. As Thomas Higham at the Radiocarbon Dating Laboratory at the University of Waikato explains, contamination from animals, certain soils, rootlet intrusion, and archaeologists' hair or tobacco during handling can interfere with dating accuracy. According to North Carolina State University, radiocarbon experts have developed methods of pretreating the artifacts to remove unrelated traces of carbon.
Future
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Marvin Rowe at Texas A&M University and Karen Steelman at the University of Central Arkansas have worked with colleagues to invent a new avenue for radiocarbon dating called plasma oxidation. Using this method, researchers place an artifact in a plasma chamber and use a radio frequency to produce a cold oxygen plasma, or ionized gas, to oxidize the artifact's surface layer of organic carbon. This is a non-intrusive way of calculating the amount of carbon in an artifact that researchers hope will aid in the future of radiocarbon dating.
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References
- C4 Dating: The Method; Thomas Higham
- Radiocarbon: Radiocarbon Dating of Scrolls and Linen Fragments From the Judean Desert; A.J. Timothy Jull, Douglas J. Donahue, Magen Broshi, Emanuel Tov; 1995
- BBC: Dig Pinpoints Stonehenge Origins; James Morgan; Sep. 21, 2008
- Public Broadcasting Service: The Dating Game; Rick Groleau; November 2000
- Arizona State University: Accelerator Mass Spectrometry Laboratory: History of Radiocarbon Dating
Resources
- Photo Credit stonehenge image by Horticulture from Fotolia.com
