By GriffonDecember 29, in Physics. I've been poking about on the internet again as you do and found a whole load of stuff by creationists about the problems with carbon 14 radiometric dating.
Specifically they report with some glee that coal has been found to contain measurable amounts of carbon14 which it should not of course because it is about million years old and "Radiocarbon dating physics problem" from the carboniferous period.
C14 has a half life of years and is only good to date objects to 50, years or so. Although I can find any number of references to this seemingly vital finding on the creationist sites, I can find almost no attempt to refute or explain this anomaly on serious science sites.
This looks like a serious oversight to me.
There seem to be some unsubstantiated references to the possibility of neutrons generated by uranium decay resulting in an anomalously high presence of C The small apparent non-zero values are less than measurement error.
In words, the readings are consistent with zero C14 content. In fact, the experiments cited by the creationists appear to be attempts to establish the measurement error of there equipment. Older carbon dating techniques directly detected decays of C14 atoms. If the material is too old, the small amount of C14 present may not decay in the measurement interval.
Newer, more accurate techniques use mass spectroscopy. Mass spectroscopy, like any man-made measurement, is not perfect.
In particular, given a pure sample of C12, I suspect a mass spectrometer would indicate that a non-zero amount of C14 present. It is nigh impossible to measure exactly zero. It doesn't take much contamination to spoil a sample with near-zero quantity of C Creationists pounce on this explanation as meaning all carbon 14 readings are suspect.
While that same level of contamination if this is the explanation will add some error to the dating of some reasonably aged sample, the error will be small -- so long as the sample is not too old. The contamination is additive, not proportional. Alternate source of C14 production. Natural diamonds are not pure carbon. The most common contaminant is nitrogen, 0.
Nearby radioactive material could trigger exactly the same C14 production process from nitrogen as occurs in the upper atmosphere, albeit at much reduced rate. Another possible avenue is C13, which has a small but non-zero neutron absorption cross section.
By either mechanism, this is essentially internal contamination. All this means is that measured dates older than some oldest reliable date are just that -- to old to date reliably. I might be able to see if I can come up with some references. I won't be able to do so in the near term -- my wife and kids want me to stop dorking with the internet and go out to eat.
The article you were looking for is hereand yeah, it looks like you're right. Here is a very detailed explanation: I think that should be I know I visited talkorigins.
What is more alarming Radiocarbon dating physics problem that the Google searches for "carbon 14 RATE", "carbon 14 diamond", and "carbon 14 coal" yield hits predominantly in woowoo fundamentalist sites, and no hits on the first 15 pages 10 links per page to anything at talkorigins.
I eventually managed to find an excellent article see the top of this post using pandasthumb. That led me to this non-technical article.
I think the news item on their front page refers to a much older event. What happened, from what I recall, is that someone hacked TalkOrigins and managed to get Radiocarbon dating physics problem site to display hidden spam links at the bottom of pages, making Google think it was a spam site and thus getting it removed from Google. They fixed that issue a while ago. PZ Myers says they've had some technical issues. I am working my way through Kirk Bertsche's 9 page essay on the subject.
Thanks DH for this link. This article does a good job at explaining the technical complexities of measuring the very small amounts of C14 present in these ancient samples and why non-zero amounts are measured. I'm a complete non-expert in this field of radiometric dating, but it strikes me "Radiocarbon dating physics problem" this how contamination by modern carbon introduced during sample preparation seems to be a severe issue.
I'm wonder whether they've extracted samples under an inert atmosphere and then used laser ablation to ionize samples in their mass spectrometers?
I'm probably teaching grandmother to suck eggs, as the old saying goes. Getting back to my OP - I feel that some definitive work needs to be done in this area.
It's easy to see that the sceptical creationist is Radiocarbon dating physics problem going to see the scientific response as making excuses for the data instead of holding up some hard data that either explains or explodes the anomaly.