Radioisotope rock daters of the uniformitarian bent presume to know the original ratio of parent radioactive material to its non-radioactivce daughter product (such as radioactive uranium to stable radium) when the rock was formed in order to compare to the current ratio to then state the supposed age of the (igneous) rock’s formation, but they can’t know with any certainty that their estimation of the initial ratio is correct (because daughter material forms along with the parent material in much varying degrees when the igneous rocks congeal from molten state), and they can’t even know that the rates of radioactive decay have not changed through time, nor that fractionation during igneous rock formation doesn’t cause greatly exaggerated radioisotope dates, among other reasons as explained if now you will google search Factors Inaccurate Radioisotope Dates, Jon Covey’s work will be very helpful.
