Because atmospheric carbon 14 arises at about the same rate that the atom decays, Earth's levels of carbon 14 have remained fairly constant.
Once an organism is dead, however, no new carbon is actively absorbed by its tissues, and its carbon 14 gradually decays.
Keep that in mind when you think about working out the age of something. Actually, knowing the starting time is still not enough.
During the race you have to watch the swimmer and count how many laps he has swum so you know that he has done 1,500 metres.
When I have asked an audience this question they have looked at me incredulously and said, “Starting time?
” They realize that you cannot know how long the swimmer took unless you knew the time on the wristwatch when the race started.
Obviously, it is in the best interests of Evolutionists to prove an Old Earth. They feel compelled to push Old Earth as a means to remove God from public education.
And so we have the Question: "What is the Age of the Earth? This is a contradiction, as an atheistic worldview is no less "religious" than a Creationist worldview.
A very small percentage of carbon, however, consists of the isotope carbon 14, or radiocarbon, which is unstable.
Carbon 14 has a half-life of 5,780 years, and is continuously created in Earth's atmosphere through the interaction of nitrogen and gamma rays from outer space.
Libby thus reasoned that by measuring carbon 14 levels in the remains of an organism that died long ago, one could estimate the time of its death.