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→Zircon Dating: Why U-Th dating is relevant, speed of light argument, etc.
::::The composition of these crystals is the strongest evidence against the conjecture of Young Earth Creationism, but until yesterday there was absolutely no discussion concerning them on this article. I think that is irresponsible. --[[User:MichaelK|MichaelK]] 13:42, 30 April 2008 (EDT)
::::The composition of these crystals is the strongest evidence against the conjecture of Young Earth Creationism, but until yesterday there was absolutely no discussion concerning them on this article. I think that is irresponsible. --[[User:MichaelK|MichaelK]] 13:42, 30 April 2008 (EDT)
::::: Okay, I've had a reply the enquiry I made about the reference to the U-Th dating in the article I linked to. My e-mail was passed on to the article's author himself, so the reply is from him.{{QuoteBox|...the two Uranium isotopes produced a concordant plot. That is, although the two isotopes decay at different rates, they each produced a set of points that fell approximately on the same line and thus gave what appeared to be the same age estimate. But the U/Thorium comparison was wildly discordant; the two sets of points did not fall on the same line. This indicates that the zircon had not been behaving as a closed system (a basic requirement for the age calculation to be valid). Either thorium or uranium had leached in or out, or both, or all together, in who-knows-what amounts. This makes the zircon undatable according to the U/Th concordia method. If the zircon is undatable by one method because it is not a closed system, then it is logically undateable by the other method for the same reason...}}
::::: If I understand it correctly, thorium is part of the uranium decay chain, so thorium should have been present also, but wasn't.
::::: I think the point about the range of ages is that, if you get a range of ages, why assume that they are all correct? If they all agreed, it would be claimed that this agreement supports the accuracy of the dates. But if they don't all agree, it just means that they are of different ages. Heads you win tails I lose.
::::: No, you aren't ''forced'' to agree with one of my three choices. That simply seemed to cover all possibilities. I originally had two, but then realised that there was a third possibility. If you want to claim something different, you can do so. But you've gone for number two, without explaining why my dismissal of it was invalid.
::::: What is so incorrect about proposing a change in the speed of light based on actual measurements? You seem to be arguing that measurements are irrelevant when they don't fit the theory. ''That'' is pseudoscience.
::::: I think your point about lead entering the crystals has been answered: The U-Th method indicates that they were ''not'' closed systems, so ''something'' is wrong, whether it's lead entering, uranium leaving, or something else.
::::: I've heard many, many arguments against creationism, and these zircon crystals don't figure very high on that list of arguments, if I've ever heard them at all. So it seems unlikely that they are the "strongest evidence" against YEC, and with the article I linked to (and the supporting information), it's by no means clear that this evidence is any better than any other.
::::: As for a section on criticisms, that depends on whether there are any criticisms that don't have answers (i.e. something that doesn't fit under the ''Responses to criticisms'' section).
::::: [[User:Philip J. Rayment|Philip J. Rayment]] 11:38, 6 May 2008 (EDT)