Four assumptions that underlie radiometric dating methods
New data collected by secular researchers has confirmed what creation scientists discovered decades ago—geologists’ assumptions about radioactive decay are not always correct.For a century, the radioactive decay of unstable elements into more stable ones has been used as a natural clock to estimate the age of earth materials.In the case of carbon dating, it is not the initial quantity that is important, but the initial ratio of C, but the same principle otherwise applies.Recognizing this problem, scientists try to focus on rocks that do not contain the decay product originally.A very common claim of young earth creationists in trying to reject the evidence for an old earth is to loudly proclaim that radiometric dating methods “makes assumptions” and that these “assumptions” are somehow fatally flawed or not supported by evidence.These claims generally land in three different categories: (1) radiometric dating assumes that initial conditions (concentrations of mother and daughter nuclei) are known, (2) radiometric dating assumes that rocks are closed systems and (3) radiometric dating assumes that decay rates are constant.
While doing so, we will have to learn about how radiometric dating works.
Indeed, by doing almost 20 seconds of research on google (type in “variations in C14”, click on Google Scholar) the second link is this article from 1954: Carbon 13 in plants and the relationships between carbon 13 and carbon 14 variations in nature So, this issue has been known about for a long time. Then we compare the two and adjust the radiocarbon date to the known date. That’s less than 1% if you’re interested in that sort of thing. But this is already almost a thousand words and I’ve only done ONE! Long story short, scientists have always known that variations in C-14 concentration happen.
Do you honestly think that no one has done anything about it? By making thousands (if not millions) of these adjustments we get a very good idea of how old a piece of unknown material can be. The 2009 calibration set extends the ‘well calibrated range’ to 50,000 years using the varves in a Japanese lake. This is unlike the creationists which think it happened, but can’t be bothered to check.
With uranium-lead dating, for example, the process assumes the original proportion of uranium in the sample.
One assumption that can be made is that all the lead in the sample was once uranium, but if there was lead there to start with, this assumption is not valid, and any date based on that assumption will be incorrect (too old).