So, we have a “clock” which starts ticking the moment something dies.
Obviously, this works only for things which were once living.
Clearly, such huge time periods cannot be fitted into the Bible without compromising what the Bible says about the goodness of God and the origin of sin, death and suffering—the reason Jesus came into the world (See Six Days? He said, This only makes sense with a time-line beginning with the creation week thousands of years ago.
It makes no sense at all if man appeared at the end of billions of years.
It cannot be used to date volcanic rocks, for example.
The rate of decay of N in 5,730 years (plus or minus 40 years).
To derive ages from such measurements, unprovable assumptions have to be made such as: There is plenty of evidence that the radioisotope dating systems are not the infallible techniques many think, and that they are not measuring millions of years. For example, deeper rocks often tend to give older “ages.” Creationists agree that the deeper rocks are generally older, but not by millions of years.
Geologist John Woodmorappe, in his devastating critique of radioactive dating, points out that there are other large-scale trends in the rocks that have nothing to do with radioactive decay.
The amount of cosmic rays reaching the Earth varies with the sun's activity, and with the Earth's passage through magnetic clouds as the solar system travels around the Milky Way galaxy.
Since the flood was accompanied by much volcanism (see Noah's Flood…, How did animals get from the Ark to isolated places? ), fossils formed in the early post-flood period would give radiocarbon ages older than they really are.
In summary, the carbon-14 method, when corrected for the effects of the flood, can give useful results, but needs to be applied carefully.
Familiar to us as the black substance in charred wood, as diamonds, and the graphite in “lead” pencils, carbon comes in several forms, or isotopes.
One rare form has atoms that are 14 times as heavy as hydrogen atoms: carbon-14, or C ratio gets smaller.