Carbon dating how does it work
After all, we should be able to estimate how long ago a creature lived based on how much radiocarbon is left in its body. Radiocarbon (carbon-14) is a very unstable element that quickly changes into nitrogen.
Half the original quantity of carbon-14 will decay back to the stable element nitrogen-14 after only 5,730 years.
Knowing the number of atoms that decayed in our sample over a month, we can calculate the radiocarbon decay rate.
The standard way of expressing the decay rate is called the half-life.5 It’s defined as the time it takes half a given quantity of a radioactive element to decay.
Since the atmosphere is composed of about 78 percent nitrogen,2 a lot of radiocarbon atoms are produced—in total about 16.5 lbs. These rapidly combine with oxygen atoms (the second most abundant element in the atmosphere, at 21 percent) to form carbon dioxide (CO This carbon dioxide, now radioactive with carbon-14, is otherwise chemically indistinguishable from the normal carbon dioxide in the atmosphere, which is slightly lighter because it contains normal carbon-12.
Radioactive and non-radioactive carbon dioxide mix throughout the atmosphere, and dissolve in the oceans.
Instead, the radiocarbon atoms in their bodies slowly decay away, so the ratio of carbon-14 atoms to regular carbon atoms will steadily decrease over time (figure 3).
Radiocarbon (carbon-14 or C) forms continually today in the earth’s upper atmosphere.
And as far as we know, it has been forming in the earth’s upper atmosphere at least since the Fall, after the atmosphere was made back on Day Two of creation week (part of the expanse, or firmament, described in Genesis 1:6–8). Cosmic rays from outer space are continually bombarding the upper atmosphere of the earth, producing fast-moving neutrons (sub-atomic particles carrying no electric charge) (figure 1).1 These fast-moving neutrons collide with nitrogen-14 atoms, the most abundant element in the upper atmosphere, converting them into radiocarbon (carbon-14) atoms.
If we assume that the mammoth originally had the same number of carbon-14 atoms in its bones as living animals do today (estimated at one carbon-14 atom for every trillion carbon-12 atoms), then, because we also know the radiocarbon decay rate, we can calculate how long ago the mammoth died. This dating method is also similar to the principle behind an hourglass (figure 4).
The sand grains that originally filled the top bowl represent the carbon-14 atoms in the living mammoth just before it died.