How a bone tells its own age: carbon-14 and the clock that starts at death
30seconds
Every living thing carries a trace of carbon-14, about one atom in a trillion, topped up with every meal. At death the topping-up stops and the clock starts: half of it decays every 5,730 years.
Watch 800 atoms decay at random, then play detective with a mystery sample. Learn how Willard Libby tested the idea on Egyptian kings' tombs in 1949, why tree rings correct the answer, and why the clock runs out at about 50,000 years.
Deep dive · 4 min
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