That is, they take up less than would be expected and so they test older than they really are.
When a “date” differs from that expected, researchers readily invent excuses for rejecting the result.
The common application of such posterior reasoning shows that radiometric dating has serious problems.
This also has to be corrected for. Second, the ratio of C in the atmosphere at that time to be estimated, and so partial calibration of the “clock” is possible.
Accordingly, carbon dating carefully applied to items from historical times can be useful.
These techniques, unlike carbon dating, mostly use the relative concentrations of parent and daughter products in radioactive decay chains.
For example, potassium-40 decays to argon-40; uranium-238 decays to lead-206 via other elements like radium; uranium-235 decays to lead-207; rubidium-87 decays to strontium-87; etc.
The strength of the Earth's magnetic field affects the amount of cosmic rays entering the atmosphere.
A stronger magnetic field deflects more cosmic rays away from the Earth.
This is the “half-life.” So, in two half-lives, or 11,460 years, only one-quarter of that in living organisms at present, then it has a theoretical age of 11,460 years.