Assumptions of radiometric dating
This amount is often unknown and is one of the downfalls of conventional radiometric dating.However, isochron dating bypasses this assumption, as explained below. The final condition is the number of atoms of parent and daughter isotopes remaining in the rock and can easily be measured in a lab.In most cases, the slope of the line generated by the isochron method gives an age for a rock sample of millions, or even billions of years.In general, these ages are supported by the science community, who declare that the Earth is about 4.5 billion years old.
These creationists challenge the assumptions made by the isochron dating method itself.According to Brent Dalrymple (20-69), "the trick to the isochron diagram is the normalization of both parent and daughter isotope to a third isotope." This third isotope is the non-decay product isotope of the same element as the daughter element.In the initial state, the graph of daughter isotope to the third isotope versus parent isotope to the third isotope should result in a straight, horizontal line.Based on the assumptions of basic radioactive dating, the problem of an unknown initial amount of daughter isotope is eliminated by the definition of the isochron itself. If contamination has occurred within a sample, the ratios from the sample shouldn't fall on a line.