Though the measurements of these elements are very precise, the assumptions upon which their usefulness as a clock rests are questionable at best.
In a article on Brennecka’s findings, Gerald Wasserburg, emeritus professor of geology at Caltech, commented, “Everybody was sitting on this two-legged stool claiming it was very stable, but it turns out it’s not.” To be fair, however, it wasn’t “everybody” who claimed this.
Even the solar system has been dated using one of these systems, by measuring the amount of a decaying element and comparing it to the amount of its stable (decayed) daughter material in meteorites.
However, a recent analysis using state-of-the-art equipment found that a basic assumption underlying one of these clock systems needs to be re-evaluated.
that strong gravitational perturbations by the planets, especially Jupiter, can put meteoroids into Earth-crossing orbits.
Not all meteoroids need to have formed in this region, however, as there are a number of processes that can cause their orbits to migrate over long time periods.
In modern usage the term is broadly applied to similar objects that land on the surface of other comparatively large bodies.
For years, creation researchers have published ample data to refute the assumed reliability of nuclear decay clocks in general, as well as specifically for Lead.
For example, in 1979, John Woodmorappe catalogued scores of discordant dates “determined” by isotope decay systems, all published in secular literature.
Gregory Brennecka of Arizona State University and colleagues measured the relative amounts of Uranium 238 to Uranium 235 from several samples taken from the large Allende meteorite, named for the village in Mexico near where it landed in 1969.
With the more sensitive instrument, they detected small differences in isotope ratios from different inclusions within the same meteorite..
This age was based on the belief that the rate of decay has been constant, and that Uranium 238 will be present in a known ratio to Uranium 235.