Carbon dating, or radiocarbon dating, is a scientific method used to determine the age of an object that contains organic material. It is based on the measurement of the amount of radioactive carbon-14 () remaining in the object.
How It Works:
1. Carbon-14 Formation:
Carbon-14 is a radioactive isotope of carbon that is formed in the upper atmosphere when cosmic rays interact with nitrogen-14 ().
This carbon-14 gets incorporated into carbon dioxide (), which is absorbed by plants during photosynthesis and enters the food chain as animals eat plants.
2. Absorption by Living Organisms:
While an organism is alive, it constantly takes in carbon-14 (and the stable isotope carbon-12, ) from the atmosphere or through its diet.
The ratio of to in living organisms is relatively constant.
3. Decay After Death:
When an organism dies, it stops absorbing carbon.
The in the organism's remains begins to decay into nitrogen-14 at a known rate, called its half-life (about 5730 years).
4. Measuring the Ratio:
By measuring the remaining amount of in a sample and comparing it to the initial levels, scientists can estimate how long it has been since the organism died.
Applications:
Dating ancient fossils, bones, wood, and other organic remains.
Determining the age of archaeological artifacts.
Studying historical and environmental changes.
Limitations:
Effective for samples up to about 50,000 years old (beyond this, the levels are too low to measure accurately).
Requires careful calibration due to fluctuations in atmospheric levels over time.
