quote:
Dating methods are theoretical. Here is a question. Even if they are near to being correct, How do you know, I mean, How do you verify those dates? You can't, nobody has lived that long.
Dating methods are
not theoretical. They are based on practical observations and measurements. Taking radio-dating, the half-lives of radiactive substances are measured in the lab ( I've done it myself in a Physics practical at Glasgow University many years ago - and with a gold-leaf electroscope!). It is a total fallacy that you need to observe them over a complete half-life. Given a sufficiently large sample and sufficiently accurate instrumentation, observation over a very small (compared to the half-life) time suffices.
How do we know the half-lives are constant over time. Two reasons. First, a negative reason, is the half lives
had changed then the physical laws in the past would differ in a way that would be observable today.
Secondly, a positive reason, observations of radioactive decay in supernova show exactly the same decay rates as measured today.
Thirdly, again positive, all the methods (radiometric and non-radiometric) agree within the limits of accuracy of the methods.
Finally, and linked to the previous point, if the timing rates have changed
all these different methods would have to change by exactly the same ratio in order to preserve the concordance of the results. This is physically impossible, at least for radio-dating. Any conceviable way in which decay rates would change would change the decay rates of different elements in a different way.
There is a very good exposition of the subject
here
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