How does carbon 14 dating work? And should it be used to determine the age of rocks or fossils?

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When the radiation of the sun hits the atmosphere of the earth, this energy converts about 21 pounds of nitrogen into radioactive carbon 14. Living organisms are constantly taking Carbon 14 into their bodies along with other carbon isotopes. When the organisms die, they stop incorporating new carbon 14, and the old carbon 14 starts to decay back into Nitrogen 14 by emitting beta particles. The older an organism’s remains are, the less beta radiation it emits because its carbon 14 is steadily decaying at a predictable rate.

Some teach that radiocarbon dating proves billions of years. But scientists know it can’t, because carbon 14 decays too fast. Its half-life is only 5,730 years—that is, every 5,730 years, half of it decays away. So, after two half-lives, a quarter is left; after three half-lives, only an eighth; after 10 half-lives, less than a thousandth is left which means that after about 5 half-lives the difference is not measurable with any degree of accuracy.

Therefore, radiocarbon dating doesn’t work well on objects much older than twenty thousand years, because such objects have so little carbon 14 left that their beta radiation is taken out by the background radiation of cosmic rays and potassium 40 decay. But younger objects can easily be dated, because they still emit plenty of beta radiation, enough to be measured after the background radiation has been subtracted out of the total beta radiation.

Hurley points out: “Without rather special developmental work, it is not generally practicable to measure ages in excess of about twenty thousand years, because the radioactivity of the carbon becomes so slight that it is difficult to get an accurate measurement above background radiation.” Hurley, Patrick M. 1959. How Old Is the Earth? New York: Doubleday & Co. p. 108.

Thus, carbon dating can’t be used to date rocks or fossils. It is only useful for once-living things which still contain carbon, like flesh or bone or wood. Rocks and fossils, consisting only of inorganic minerals, cannot be dated by this method.

In His service,

BibleAsk Team

 

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