Radiocarbon dating is a method used to determine the age of an object containing organic material by measuring the amount of carbon-14 it contains. It works as follows:
- Carbon Isotopes: Carbon exists in three isotopes: carbon-12 (C-12), carbon-13 (C-13), and carbon-14 (C-14). C-12 and C-13 are stable, while C-14 is radioactive.
- Absorption of Carbon: Living organisms continuously absorb carbon from their environment, including C-14, during their lifetime. This process occurs through photosynthesis in plants or by eating plants and other organisms in animals.
- Decay of C-14: After an organism dies, it stops absorbing carbon. The C-14 in the organism begins to decay into nitrogen-14 (N-14) at a known rate, with a half-life of about 5,730 years. This means half of the C-14 in a sample will decay every 5,730 years.
- Measuring C-14: By measuring the remaining amount of C-14 in a sample, scientists can calculate how long it has been since the organism died. The less C-14 left, the older the sample.
- Calibration: Since the amount of C-14 in the atmosphere fluctuates over time due to factors like solar activity, radiocarbon dates are calibrated using data from tree rings (dendrochronology) and other sources to give a more accurate age.
This technique is mainly used to date once-living materials like bones, wood, charcoal, and shells, and is typically effective for materials that are up to about 50,000 years old.