Carbon dating, also known as radiocarbon dating, is a scientific method used to determine the age of organic materials up to about 60,000 years old. It works by measuring the amount of carbon-14 (a radioactive isotope of carbon) remaining in a sample from a once-living organism. Living organisms continuously absorb carbon-14 from the atmosphere, but when they die, they stop absorbing it, and the carbon-14 begins to decay into other atoms at a predictable rate (half-life of about 5,730 years). By measuring the remaining carbon-14 in the sample and comparing it to the expected initial amount, scientists can estimate how long it has been since that organism died. This method was developed in the late 1940s by Willard Libby and his team at the University of Chicago. Radiocarbon dating has been widely used in archaeology, geology, and other fields to date fossils, artifacts, and environmental samples, helping to understand human history, climate change, and geological events.
How carbon dating works
- Cosmic rays in the Earth's atmosphere create carbon-14 by converting nitrogen-14.
- Carbon-14 combines with oxygen to form carbon dioxide, which is absorbed by plants and enters the food chain.
- Living organisms maintain a constant ratio of carbon-14 to carbon-12 while alive.
- After death, no new carbon-14 is absorbed, and the existing carbon-14 decays at a steady rate.
- Measuring the leftover carbon-14 allows scientists to calculate the time since death by the decay law.
