Carbon-14 has a half-life of 5,730 ± 40 years— during the succeeding 5,730 years.
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.
A child mummy is found high in the Andes and the archaeologist says the child lived more than 2,000 years ago.
How do scientists know how old an object or human remains are?
After plants die or are consumed by other organisms, the incorporation of all carbon isotopes, including 14C, stops.
Thereafter, the concentration (fraction) of 14C declines at a fixed exponential rate due to the radioactive decay of 14C. ) Comparing the remaining 14C fraction of a sample to that expected from atmospheric 14C allows us to estimate the age of the sample.
Beyond ∼12 000 years, marine corals and foraminifera have been used to further construct a calibration which now extends back to 26 000 years ago.This technique enables milligram-sized samples of carbon to be dated reliably.In recent years, research in pre-treatment chemistry and the dating of small samples down to 100 micrograms of carbon have further improved the method.In the wake of the first application of the method, several major developments have enhanced its use.One of these was the recognition of the need to calibrate radiocarbon due to variations in the production rate of C.