These long time periods are computed by measuring the ratio of daughter to parent substance in a rock and inferring an age based on this ratio.This age is computed under the assumption that the parent substance (say, uranium) gradually decays to the daughter substance (say, lead), so the higher the ratio of lead to uranium, the older the rock must be.With uranium-lead dating, for example, the process assumes the original proportion of uranium in the sample.
When I first became interested in the creation-evolution debate, in late 1994, I looked around for sources that clearly and simply explained what radiometric dating is and why young-Earth creationists are driven to discredit it.
The only dating methods discussed (over and over) by evolution-believing scientists and the mass media are those that supposedly "prove" that the earth is billions of years old.
One of the most popular of these is known as radiometric dating. can be In other words, something in the past caused a significant amount of helium to build up inside these zircons (such as from a rapid decay episode of uranium), yet, in spite of the fact that helium has been observed to leak out readily from these zircons, it has not done so: simply because it hasn't had enough time to do so -- suggesting that the zircons themselves are only a few thousand years old."There is evidence to show ...
Because radiometric dating fails to satisfy standards of testability and falsifiability, claims based on radiometric dating may fail to qualify under the Daubert standard for court-admissible scientific evidence.
It is more accurate for shorter time periods (e.g., hundreds of years) during which control variables are less likely to change.
To me it has been a real eye opener to see all the processes that are taking place and their potential influence on radiometric dating.