Once the organism dies, however, it ceases to absorb carbon-14, so that the amount of the radiocarbon in its tissues steadily decreases.Carbon-14 has a half-life of 5,730 ± 40 years— during the succeeding 5,730 years.Radiocarbon dating uses isotopes of the element carbon. Cosmic rays – high energy particles from beyond the solar system – bombard Earth’s upper atmosphere continually, in the process creating the unstable carbon-14. Because it’s unstable, carbon-14 will eventually decay back to carbon-12 isotopes.Because the cosmic ray bombardment is fairly constant, there’s a near-constant level of carbon-14 to carbon-12 ratio in Earth’s atmosphere.Because carbon-14 decays at this constant rate, an estimate of the date at which an organism died can be made by measuring the amount of its residual radiocarbon.
The dating process is always designed to try to extract the carbon from a sample which is most representative of the original organism.This means that things like stone, metal and pottery cannot usually be directly dated by this means unless there is some organic material embedded or left as a residue.As explained below, the radiocarbon date tells us when the organism was alive (not when the material was used). "[b] Only three of the 15,000 reported ages are listed as `infinite.' "[c] Some samples of coal, oil, and natural gas, all supposedly many millions of years old have radiocarbon ages of less than 50,000 years. von Fange, "Time Upside Down," in Creation Research Society Quarterly, June 1974, p. "Although it was hailed as the answer to the prehistorian's prayer when it was first announced, there has been increasing disillusion with the [radiocarbon] method because of the chronological uncertainties—in some cases absurdities—that would follow a strict adherence to published C-14 dates . What bids to become a classic example of `C-14 irresponsibility' is the 6,000 year spread of 11 determinations for Jarmo, a prehistoric village in northeastern Iraq which, on the basis of all archeological evidence, was not occupied for more than 500 consecutive years."—*C. Reed, "Animal Domestication in the Prehistoric Near East," in Science, 130 (1959), p. "A survey of the 15,000 radiocarbon dates published through the year 1969 in the publication, Radiocarbon, revealed the following significant facts: "[a] Of the dates of 9,671 specimens of trees, animals, and man, only 1,146 or about 12 percent have radiocarbon ages greater than 12,530 years. By contrast, this revised approach has the effect of `compressing' radiocarbon time,' and speeding up the rate of man's cultural development."—Erich A.