Quantum quirk makes carbon dating possible

摘要

RADIOCARBON dating relies on carbon-14 to decode an object's age, but the isotope has steadfastly refused to divulge the key to its own unusual longevity. The answer, it seems, lies in the bizarre rules of quantum physics. Carbon-14 decays with a half-life of 5730 years, so it is often used to date objects up to about 50,000 years old (anything older would have negligible amounts of the stuff). But most other atoms that decay in the same way - by converting one of their neutrons into a proton -disappear in less than a day. So what's different about carbon-14? The nucleus of the carbon-14 isotope has six protons and eight neutrons. When it decays, one of the neutrons turns into a proton, and also releases an electron and a neutrino. The result is a nitrogen-14 nucleus with seven protons and seven neutrons.