A radiometric dating technique uses the decay of
Later, after radioactivity had been proven to be a significant source of the Earth's internal heat, he did privately admit that he might have been in error.
What is especially telling about this whole story is the conclusion of the absolute truth of the conclusion based on premises that are weak, or at least not adequately demonstrated.
Some, like Robert Gentry, have even argued that Radio-halos from rapidly decaying radioactive isotopes in granite seem to indicate that the granites were formed almost instantly.
In short, the assumption that decay rates are immune to outside influences isn't as solid as it once appeared to be.
However, if one does assume a constant decay rate, and if one starts with an originally pure sample of “parent element,” then the proportion of parent to daughter tells us the number of half-lives, which has been used to find the supposed age of igneous rocks. The conclusions of Renne and his team read as follows: Ar can be identified in volcanic sanidine, and while perhaps negligible in pre-Holocene rocks, it has important consequences for sample at the limit of the method’s applicability.
Chamberlain (1899) pointed out that Kelvin's calculations were only as good as the assumptions on which they were based.
"The fascinating impressiveness of rigorous mathematical analyses, with its atmosphere of precision and elegance, should not blind us to the defects of the premises that condition the whole process.