Welcome to the K12 section of the Radiocarbon WEBinfo site.

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Radioactive elements are unstable; they breakdown spontaneously into more stable atoms over time, a process known as radioactive decay.

Radioactive decay occurs at a constant rate, specific to each radioactive isotope.

A very small percentage of carbon, however, consists of the isotope carbon 14, or radiocarbon, which is unstable.

Carbon 14 has a half-life of 5,780 years, and is continuously created in Earth's atmosphere through the interaction of nitrogen and gamma rays from outer space.

Because atmospheric carbon 14 arises at about the same rate that the atom decays, Earth's levels of carbon 14 have remained fairly constant.

Once an organism is dead, however, no new carbon is actively absorbed by its tissues, and its carbon 14 gradually decays.

Now, when I did that, I made a pretty big assumption, and some you all have touched on this in the comments on You Tube on the last video, is how do I know that this estimate I made is based on the assumption that the amount of carbon-14 in the atmosphere would have been roughly constant from when this bone was living to now?

And so the question is, is the amount of carbon-14 in the atmosphere and in the water, and in living plants and animals, is it constant?

Rasmus Nyerup's quote reminds us of the tremendous scientific advances which have taken place in the 20th century.