As a result it is always undergoing natural radioactive decay while the abundances of the other isotopes are unchanged.
Carbon-14 is most abundant in atmospheric carbon dioxide because it is constantly being produced by collisions between nitrogen atoms and cosmic rays at the upper limits of the atmosphere.
Fifth, the release of carbon dioxide from fossil fuel burning significantly dilutes carbon 14, and researchers have no accurate way to calibrate this dilution factor.
Sixth, and perhaps most significant, astronomy provides much simpler, more consistent, and more direct methods for measuring the date for creation.
They have masses of 13 and 14 respectively and are referred to as "carbon-13" and "carbon-14." If two atoms have equal numbers of protons but differing numbers of neutrons, one is said to be an "isotope" of the other.
Carbon-13 and carbon-14 are thus isotopes of carbon-12.
Third, because carbon 14 forms from cosmic ray bombardment of nitrogen 14 (and decays back into nitrogen 14 through the release of beta particles, i.e., electrons) the effect of variations in cosmic radiation intensity (caused by altitude, depth below the earth's surface, and astronomical events) can be difficult to calibrate.
All carbon atoms have a nucleus containing six protons.
This argument was popularized by Henry Morris (1974, p.164), who used some calculations done in 1968 by Melvin Cook to get the 10,000-year figure. Whitelaw, using a greater ratio of carbon-14 production to decay, concluded that only 5000 years passed since carbon-14 started forming in the atmosphere!
The argument may be compared to filling a barrel which has numerous small holes in its sides.
Furthermore, the ratio is known to fluctuate significantly over relatively short periods of time (e.g.
Unfortunately the ratio of carbon-12 to carbon-14 has yet to reach a state of equilibrium in our atmosphere; there is more carbon-14 in the air today than there was thousands of years ago.