Year libby discovered radiocarbon dating

Because the activity of the carbon atoms decreases at a known rate, it should be possible, by measuring the remaining activity, to determine the time elapsed since death, if this occurred during the period between approximatively 500 and 30,000 years ago.This hypothesis was published by Libby in 1947, and with his great experimental skill it did not take him long to prove the validity of the theory.Similar findings were made in Iraq, showing that people lived there 25,000 years ago.This is just to mention a few of the age determinations which throw light on the prehistory of mankind.Recently dead biological substances, such as wood and plant materials, seal oil and others, showed an activity which could the calculated from the knowledge of the production of carbon-14 in the atmosphere, and its rate of decomposition.Fossil material, such as petroleum, was completely inactive; it comes from organisms which lived millions of years ago.The results he thus obtained from these control experiments left no doubts about the reliability of the method.

Carbon-14 is thus said to have a half-life of 5,600 years.It is converted into nitrogen by the emission of an electron which can be detected by a sensitive apparatus.The disintegration is such a slow procedure, however, that 5,600 years are required to convert half of these atoms into nitrogen.Traces of the first human habitations in these regions were dated to about 10,000 years ago.In the southern part of France, on the other hand, beyond the advance of the ice, remnants were found of charcoal from the campfires of human cave-dwellers, remnants which proved to be 15,000 years old.

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