And from the slope of the line we can compute the amount of time which has passed since the pool of matter became separated into individual objects.See the Isochron Dating FAQ or Faure (1986, chapter 18) for technical detail.The actual underlying assumption is that, if those requirements have not been met, there is no reason for the data points to fall on a line.The resulting plot has data points for each of five meteorites that contain varying levels of uranium, a single data point for all meteorites that do not, and one (solid circle) data point for modern terrestrial sediments.For example, Henry Morris says: He lead to similar results, i.e., a rate virtually identical to the estimated production flux.
In order to obtain a young age from their calculations, young-Earthers handwave away mechanisms by which helium can escape.
Note that young-Earthers cannot accuse us of selective use of data -- the above table includes a significant fraction of all meteorites on which isotope dating has been attempted. 286) , less than 100 meteorites have been subjected to isotope dating, and of those about 70 yield ages with low analytical error.
Further, the oldest age determinations of individual meteorites generally give concordant ages by multiple radiometric means, or multiple tests across different samples.
Helium is not light enough to escape the Earth's gravity (unlike hydrogen), and it will therefore accumulate over time.
The current level of helium in the atmosphere would accumulate in less than two hundred thousand years, therefore the Earth is young.