Radioactive carbon dating

It looks like there's been a lot of nonsense spouted in this thread. I'll respond to just one of the many issues at the moment:

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I won't waste any time stating too much how Potassium-Argon is a failure at dating recent igneous rock from lava flows.

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Of course it's a failure. By definition it has to be a failure at measuring the age of recent materials. The long half-life of 40K (over a billion years) means that it is really only effective for material older than about 100,000 years, and even that would be straining the technique a bit. It's best used on materials at least a million years old. Using K/Ar dating on a recent lava flow would be like using a yardstick to measure the width of a human hair.

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At the very least, geologists admit it doesn't work on volcanoes,...

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Hopefully you're referring again to recent volcanoes. K/Ar dating is one of the most important tools in the geologist's kit for dating ancient volcanic flows.

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The best-known "failures" of K-Ar were intentional. When the 39Ar-40Ar method was invented, scientists wanted to test it where they thought traditional K-Ar would fail. So they intentionally tried to date recent submarine lava flows off the coast of Hawaii, the theory being that the water would have cooled the lava so fast that it would incorporate initial "parentless" argon, throwing off the dates. Sure enough, the traditional K-Ar dated very old, but the new method correctly gave dates consistent with "recent".Some young earth creationists picked up these articles and began quoting the erroneous K-Ar dates as evidence of the method's failure, completely missing the point of the research and ignoring the correct 39Ar-40Ar dates.Note that there should be no problem using K-Ar for even recent lava flows, as long as it does not have parentless argon. But the error bars will be large, so it won't be too useful.

They suggest that somehow this "short half-life" 40K accounts for old dates of recent lava flows. This doesn't make any sense. It would imply:
1) the hypothesized "short half life" 40K must be present in volcanic flows, so it must be present in magma. Since its half-life is so short, to be present in the magma at any concentration it must be continually created somehow. But how? From what? If from normal K-40, it would quickly deplete the amount of K-40. And this would throw off the 39K-40K ratio, and we would see evidence of it.
2) this would affect 39Ar-40Ar dates as well as traditional K-Ar dates, so both would give old dates for recent lava flows. But this is not consistent with the data. Parentless argon explains the data much better.They hypothesize something for which there is no experimental evidence, and which seems to be inconsistent with the data. It sounds like nonsense.

I'm going to reply to myself to correct/modify my earlier statement: This is probably not correct. The hypothesized new form of 40K supposedly has a 12-hr half-life. If it takes much longer than this for the lava to cool and crystalize (which is almost certainly the case), any 40Ar from this new type of 40K will have already decayed, will not be incorporated into the crystal lattice, and will look just like parentless 40Ar. In this case, 39Ar-40Ar will still give the correct dates.

Ar-Ar is also very robust. My former colleagues used this for crater dating studies; they ONLY used Ar-Ar dates, not K-Ar, because Ar-Ar can give narrow and reliable error bars (much better than K-Ar). I've never seen the YEC's address this method, either.

I don't see any evidence that the authors of the paper have taken ANY measurements. They are simply proposing a theory and computer model, and showing the results, along with tabulated data. Not true! When the molten magma solidifies and crystalizes, initial Ar is pushed to crystal grain boundaries since it cannot chemically bond in a crystal structure. The 40K that IS incorporated into the crystal lattice slowly decays, leaving 40Ar stuck in the crystal lattice. The 39Ar-40Ar method is able to distinguish between Ar that is at grain boundaries and Ar that is trapped within the crystal lattice, so it gives accurate dates even in this case. Someone else has already posted links to some experimental data for this.

FYI, a short rebuttal of RATE's radiocarbon claims, an early version of which started a spirited discussion with Baumgardner on TheologyWeb, has just been published in Perspectives on Science and Christian Faith. It can be seen here:
RATE Dialogue - in PSCF (March 2008)An expanded analysis of the RATE claims, about 5x longer, is also available here:
RATE's Radiocarbon - Intrinsic or Contamination?Kirk Bertsche

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The "equilibrium problem" comes from websites like AnswersinGenesis:
Doesn’t Carbon-14 Dating Disprove the Bible? | Answers in Genesis

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From the AiG link: This is partly true, but the facts are being twisted. Yes, Libby assumed equilibrium. An equilibrium assumption works surprisingly well (maximum error less than 15% over the last 45,000 years) due to our large atmospheric and terrestrial carbon reservoirs which dilute the effects of non-equilibrium production rates.But with tree ring calibrations, equilibrium does NOT need to be assumed. The only assumptions are that 1) we can count annual tree rings, and 2) the trees used for calibration and the unknowns breathed the same atmospheric radiocarbon. There is NO assumption of equilibrium, original concentrations, etc. (BTW, this also gets around any claims of changes in the decay rate.)These details are mostly unknown by YECs, who persist in claiming that radiocarbon rests on many unproven assumptions. I was quizzed on this just last week by a fairly knowledgeable YEC, who seemed surprised by these details.Edited by kbertsche, : No reason given.