For example, fission track dating measures the microscopic marks left in crystals by subatomic particles from decaying isotopes.
Another example is luminescence dating, which measures the energy from radioactive decay that is trapped inside nearby crystals.
The atoms of some chemical elements have different forms, called isotopes.
These break down over time in a process scientists call radioactive decay.
No other scientific method has managed to revolutionize man’s understanding not only of his present but also of events that already happened thousands of years ago.
Archaeology and other human sciences use radiocarbon dating to prove or disprove theories.
Physical and chemical pretreatments are done on these materials to remove possible contaminants before they are analyzed for their radiocarbon content.
There are three principal techniques used to measure carbon 14 content of any given sample— gas proportional counting, liquid scintillation counting, and accelerator mass spectrometry.
Most directly measure the amount of isotopes in rocks, using a mass spectrometer.Because of the fairly fast decay rate of carbon-14, it can only be used on material up to about 60,000 years old.Geologists use radiocarbon to date such materials as wood and pollen trapped in sediment, which indicates the date of the sediment itself.When they die, they stop exchanging carbon with the biosphere and their carbon 14 content then starts to decrease at a rate determined by the law of radioactive decay.Radiocarbon dating is essentially a method designed to measure residual radioactivity.These rates of decay are known, so if you can measure the proportion of parent and daughter isotopes in rocks now, you can calculate when the rocks were formed.