Since it would only take less than 50,000 years to reach equilibrium from a world with no C-14 at the start, this always seemed like a good assumption.That is until careful measurements revealed a significant disequalibrium. All the present C-14 would accumulate, at present rates of production and build up, in less than 30,000 years!Furthermore, the assumptions on which it is based and the conditions which must be satisfied are questionable, and in practice, no one trusts it beyond about 3,000 or 4,000 years, and then only if it can be checked by some historical means.The method assumes, among other things, that the earth's age exceeds the time it would take for C-14 production to be in equilibrium with C-14 decay.Thus the ratio of stable C-12 to unstable C-14, which is known in today's open environment, changes over time in an isolated specimen. As long as the tree lives, it absorbs carbon from the atmosphere in the form of carbon dioxide, both C-12 and C-14.Once the tree dies, it ceases to take in new carbon, and any C-14 present begins to decay.Perhaps no concept in science is as misunderstood as "carbon dating." Almost everyone thinks carbon dating speaks of millions or billions of years.But, carbon dating can't be used to date either rocks or fossils.
One rare form has atoms that are 14 times as heavy as hydrogen atoms: carbon-14, or C ratio gets smaller.Carbon normally occurs as Carbon-12, but radioactive Carbon-14 may sometimes be formed in the outer atmosphere as Nitrogen-14 undergoes cosmic ray bombardment.The resulting C-14 is unstable and decays back to N-14 with a measured half-life of approximately 5,730 years.It is only useful for once-living things which still contain carbon, like flesh or bone or wood.Rocks and fossils, consisting only of inorganic minerals, cannot be dated by this scheme.C) dating usually want to know about the radiometric dating methods that are claimed to give millions and billions of years—carbon dating can only give thousands of years.