How can carbon 14 be used to date organic material?
All organic material must 'stock up' carbon atoms for various reasons, some of which randomly happen to be carbon-14. When the organism dies, it stops collecting carbon-14. This carbon-14 is radioactive, so over time it will become less radioactive. Scientists can use its level of radioactivity and compare it to the half life of carbon-14, which is the time taken for it to become half as radioactive as before. For Carbon-14, this is 5,730 years.