Evolutionary dating flaws
So Curtis and others redated the KBS tuff using selected pumice and feldspar samples, and obtained an age of 1.82 million years.This new date agreed with the appearance of the new skull.The current model of radioisotope dating is based on that idea.But that model doesn't account for differential mass diffusion -- the tendency of different atoms to diffuse though a material at different rates."The rate of diffusion will vary, based on the sample -- what type of rock it is, the number of cracks and amount of surface area, and so on," Hayes says."So, there's not a simple equation that can be applied to every circumstance.
By evaluating the concentrations of all of these isotopes in a rock sample, scientists can determine what its original make-up of strontium and rubidium were.The number of protons in an atom determines which element it is, while the number of neutrons determines which isotope it is.For example, strontium-86 has 38 protons and 48 neutrons, whereas strontium-87 has 38 protons and 49 neutrons.And atoms of strontium-86 can diffuse more readily than atoms of strontium-87 or rubidium, simply because atoms of strontium-86 are smaller."It's a slow process, but not necessarily a negligible one when you're talking about geological time scales," says Robert Hayes, an associate professor of nuclear engineering at NC State and author of a paper describing the work.