What is carbon dating in history

How do scientists figure out how old things are?

Carbon , C , 14 C or radiocarbon , is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues to date archaeological, geological and hydrogeological samples. Its existence had been suggested by Franz Kurie in The primary natural source of carbon on Earth is cosmic ray action on nitrogen in the atmosphere, and it is therefore a cosmogenic nuclide. However, open-air nuclear testing between and contributed to this pool. The different isotopes of carbon do not differ appreciably in their chemical properties. This resemblance is used in chemical and biological research, in a technique called carbon labeling : carbon atoms can be used to replace nonradioactive carbon, in order to trace chemical and biochemical reactions involving carbon atoms from any given organic compound. As usual with beta decay, almost all the decay energy is carried away by the beta particle and the neutrino.

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Through further research, it was discovered that the half-life of 14C was approximately 5, years and that it was created naturally in the atmosphere through the interaction of cosmic rays with atmospheric nitrogen. A few years after the discovery of 14C, Willard Libby a Professor of Chemistry at the University of Chicago connected the production of atmospheric 14C with plants. He hypothesized that plants absorbed 14C alongside non-radioactive carbon during photosynthesis. Based on this connection between the life of the plant and 14C uptake, he further theorized that the plant would stop taking up 14C after death, and the 14C within the plant structure would decay at the known rate without replacement. This extraordinary discovery earned Libby a Nobel Prize. Following the discovery of 14C and its dating potential, the search was on to identify a practical and efficient method of measuring 14C in samples.

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The ability to precisely date, or identify the age of an object, can teach us when Earth formed, help reveal past climates and tell us how early humans lived. So how do scientists do it? Radiocarbon dating is the most common method by far, according to experts. This method involves measuring quantities of carbon, a radioactive carbon isotope — or version of an atom with a different number of neutrons. Carbon is ubiquitous in the environment. After it forms high up in the atmosphere, plants breathe it in and animals breathe it out, said Thomas Higham, an archaeologist and radiocarbon dating specialist at the University of Oxford in England.

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Carbon-14 dating, explained

You probably have seen or read news stories about fascinating ancient artifacts. An archaeologist finds a child mummy high in the Andes and says the child lived more than 2, years ago. How do scientists know how old an object or human remains are? What methods do they use and how do these methods work?

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