This serves as strong evidence for the reliability of radiometric dating methods. These isotopes differ in the number of neutrons they have in their nuclei.Those isotopes that are not stable decay into daughter nuclei.If the samples have been undisturbed closed systems since formation, the data will fall on the same line (the isochron from which the diagram is named).The slope of this line is a function of the age of the rock. The reason scientists normalize with another stable isotope of the same element as the daughter is because most chemical or physical processes that occurs normally in nature does not differentiate between different isotopes of the same element when the difference in mass is as small as it is between isotopes of the same element that is used in radiometric dating.As time goes on, the ratio of the parent to daughter nuclei will change and decrease (as more parent nuclei decay into daughter nuclei, the former decreases and the latter increases).Measuring this ratio gives us an idea of how long ago the rock formed. Doesn’t this assume that the rocks are closed systems?An isochron diagram is obtained by looking at many minerals from the same rock or from rocks forming from the same parent mineral.Data is plotted on a simple two dimensional graph; the parent isotope on the x-axis and the daughter isotope on the y-axis.
Now, creationists will claim that scientists are just somehow assuming that if samples show an age that does not fit their preconceptions, the sample must be contaminated or leaky. To see why, we need to look deeper into radiometric dating methods.Surely, if some daughter nuclei left the rock or parent nuclei entered the rock, the dates would come out all wrong! Follow Debunking Denialism on Facebook or Twitter for new updates.While this is technically true, there are several mini-industries dedicated developing methods and techniques to make sure that there is no contamination and check to see if the rocks where disturbed between forming and being tested by scientists. On of the great things about many forms of radiometric dating is that they are self-checking.So far from rejecting samples because they do not fit a preconceived notion of what the age be, scientists reject samples because there is ample evidence that it has been disturbed: the data points do not lie on the isochron lines.Scientists do not assume that rocks have been closed systems; it is a well-supported conclusion from experiments.Let us critically examine each of these claims and see if they hold up against the science.While doing so, we will have to learn about how radiometric dating works.A very important tool in radiometric dating is the so called isochron diagram and it holds the key to refuting the central creationist claims about radiometric dating.One of the most beneficial things about it is that it can check itself for accuracy; the method tells you how well the rocks have been closed systems.But what about assuming that initial amounts are known?A second property of isochron diagrams is that it actually gives the initial amount of daughter isotope as a result of the method. At this intersect, the ratio of parent/(another stable isotope of the same element as the daughter) is by definition 0 and so no amount of the daughter here is produced by decay of the parent in the rock.