Origin of carbon dating
“It is another sobering example of cocked-up dates,” says Higham, whose laboratory is leading a revolution in radiocarbon dating.
When the neutron collides, a nitrogen-14 (seven protons, seven neutrons) atom turns into a carbon-14 atom (six protons, eight neutrons) and a hydrogen atom (one proton, zero neutrons).“We know that it is older than Christendom,” he wrote, “but whether by a couple of years or a couple of centuries or even by more than a millennium, we can do no more than guess.” The fog began to lift in the middle of the twentieth century, when US chemist Willard Libby and his colleagues showed that all formerly living things bear a clock powered by radioactive carbon-14.Organisms incorporate tiny amounts of this isotope as they grow, and they maintain a constant ratio between it and other, non-radioactive, carbon isotopes throughout their lives.Cosmic rays enter the earth's atmosphere in large numbers every day.For example, every person is hit by about half a million cosmic rays every hour.Carbon-14 is radioactive, with a half-life of about 5,700 years.
For more information on cosmic rays and half-life, as well as the process of radioactive decay, see How Nuclear Radiation Works.
Tom didn't originally plan to follow his father's path.
As a child he was obsessed with the history of the American West.
The carbon-14 atoms are always decaying, but they are being replaced by new carbon-14 atoms at a constant rate.
At this moment, your body has a certain percentage of carbon-14 atoms in it, and all living plants and animals have the same percentage.
Beside a slab of trilobites, in a quiet corner of Britain's Oxford University Museum of Natural History, lies a collection of ochre-tinted human bones known as the Red Lady of Paviland.