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What is Carbon-14?Carbon is everywhere in living things. A ‘standard’ carbon nucleus is made up of six positively charged particles called protons and six neutrons, which have no electrical charge. This gives carbon an atomic mass of 12. Protons are responsible for the electrical and chemical properties of an element. Adding one extra proton in the carbon nucleus would turn it into nitrogen. But the number of neutrons can vary. Carbon comes in different isotopes, which differ only in having a different number of neutrons.There are two stable isotopes of carbon (atomic mass 12 and 13). Carbon-14 is used in ‘carbon dating’, the most widely used method for determining the age of formerly living material. It has a mass number of 14 and a half-life of around 5730 years. As a result of cosmic radiation, a small number of atmospheric nitrogen nuclei are continuously being transformed by neutron bombardment into radioactive nuclei of carbon-14: a neutron knocks a proton out of nitrogen and takes its place. These radiocarbon atoms find their way into living trees and other plants in the form of carbon dioxide, as a result of photosynthesis. When the plant is eaten, photosynthesis stops and the ratio of radiocarbon atoms to stable carbon atoms begins to fall as the radiocarbon decays. Based on the assumption that the isotope ratio of carbon in cells of living things is identical with that in air, Willard F. Libby (1908-80) and his co-workers in 1946-47 developed a technique designed to measure the ratio 14C/12C in the specimen. This method made it possible to estimate the time that has elapsed since, for instance, a tree was cut down. Radiocarbon dating has been shown to give some meaningful results for specimens up to some 4000 years old, though its accuracy depends upon assumptions concerning past intensity of cosmic radiation, the earth magnetic field, concentration (and partial pressure) of Carbon dioxide and equilibrium between production and decay rates. These factors telescope all Radiocarbon dates into a biblical "short" time scale |
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Radiometric Dating (Answers in Genesis) Young Age Evidence (Answers in Genesis) Dating Techniques (Institute For Creation Research) See also AlphaNOVA's program Carbon-14 Dating Fact and Fiction |
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