Carbon dating half lives
Through photosynthesis carbon dioxide enters plants and algae, bringing radiocarbon into the food chain.
Radiocarbon then enters animals as they consume the plants (figure 2).
(This 5,730 year period is called the half-life of radiocarbon, figure 5).6 At this decay rate, hardly any carbon-14 atoms will remain after only 57,300 years (or ten half-lives). The decay of radiocarbon follows the exponential decay law, whereby the percentage decrease in the number of parent atoms per unit time is constant.
After each half-life of 5,730 years, the number of parent radiocarbon atoms remaining is halved.
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).