However, until a few years ago nobody had done the experimental and theoretical studies necessary to confirm this conclusion quantitatively.   In 2000 the RATE project [14] began experiments to measure the diffusion rates of helium in zircon and biotite.  We show that these data limit the age of these rocks to between 4,000 and 14,000 years. These results support our hypothesis of accelerated nuclear decay and represent strong scientific evidence for the young world of Scripture.
This shows that alleged isotopic dates of 1.5 billion years correspond to true dates of between 4,000 and 14,000 years.
However these results do not yet show that even older dates are in this time range.  It would be interesting to test zircons having even older isotopic dates to see how much helium they contain.