Carbon 14 and carbon dating
These artifacts have gone through many carbon-14 half-lives and the amount of carbon-14 remaining in them is miniscule and very difficult to detect.Carbon dating cannot be used on most fossils, not only because they are almost always too old, but also because they rarely contain the original carbon of the organism.Scientists now realize that production of carbon-14 has not been constant over the last 10,000 years, but has changed as the radiation from the sun has changed.Carbon dates reported in the 1950s and 1960s should be questioned, because those studies were conducted before carbon dating was calibrated by comparision with other dating methods.The ratio of carbon-14 to carbon-12 in the atmosphere and on earth is nearly constant, although there has been some change in carbon-14 concentration over the last 10,000 years.
Therefore, the amount of carbon-14 in an artifact decreases at a predictable rate while the amount of carbon-12 remains constant.
At any given moment all living plants and animals have approximately the same percentage of carbon-14 in their bodies.
When a plant or animal dies it stops bringing in new carbon-14.
Carbon-14 in the bodies of animals and plants is constantly decaying.
However, the decaying carbon-14 is constantly being replaced as the plant or animal consumes more carbon-14 from the air or through its food.
Nitrogen normally occurs in a seven proton, seven nuetron, nitrogen-14 state.