The carbon-14 decays with its half-life of 5,700 years, while the amount of carbon-12 remains constant in the sample.
By looking at the ratio of carbon-12 to carbon-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of a formerly living thing fairly precisely. So, if you had a fossil that had 10 percent carbon-14 compared to a living sample, then that fossil would be: t = [ ln (0.10) / (-0.693) ] x 5,700 years t = [ (-2.303) / (-0.693) ] x 5,700 years t = [ 3.323 ] x 5,700 years Because the half-life of carbon-14 is 5,700 years, it is only reliable for dating objects up to about 60,000 years old.
Love-hungry teenagers and archaeologists agree: dating is hard.
But while the difficulties of single life may be intractable, the challenge of determining the age of prehistoric artifacts and fossils is greatly aided by measuring certain radioactive isotopes.
Many people are under the false impression that carbon dating proves that dinosaurs and other extinct animals lived millions of years ago.
- At Oak Ridge National Laboratory, Scientists dated dinosaur bones using the Carbon dating method.
Carbon-14 is also passed onto the animals that eat those plants.
After death the amount of carbon-14 in the organic specimen decreases very regularly as the molecules decay.
As soon as a living organism dies, it stops taking in new carbon.
The ratio of carbon-12 to carbon-14 at the moment of death is the same as every other living thing, but the carbon-14 decays and is not replaced.