[Griffon]

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 300 million years old and dates from the carboniferous period. C14 has a half life of 5730 years and is only good to date objects to 50,000 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 C14.

Anyone have any ideas about this apparent anomaly with C14 in coal?

This post has been edited by Griffon: 29 December 2008 - 10:55 PM

[D H]

talkorigins.org supposedly has an article on this very subject (per Google), but I haven't been able to get to talkorigins for some time.

Hypothesized explanations:

#1. The small apparent non-zero values are less than measurement error. In other 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. The problem: 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.

#2. Contamination. It doesn't take much contamination to spoil a sample with near-zero quantity of C14. Creationists pounce on this explanation as meaning all carbon 14 readings are suspect. False. 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.

#3. Alternate source of C14 production. Natural diamonds are not pure carbon. The most common contaminant is nitrogen, 0.1% in gem-quality diamonds. Nearby radioactive material could trigger exactly the same C14 production process from nitrogen as occurs in the upper atmosphere, albeit at a 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.

[Cap'n Refsmmat]

http://www.toarchive.org/

Apparently they've had domain name trouble and had to switch sites.

The article you were looking for is here, and yeah, it looks like you're right.

[D H]

Here is a very detailed explanation: http://www.asa3.org/...s/carbon-kb.htm.



UPDATE, automerged with the above:

Cap said:

http://www.toarchive.org/
Apparently they've had domain name trouble and had to switch sites.

Apparently is an understatement.

toarchive said:

The cracker managed to get the TOA de-indexed by Google, and when the TOA was re-indexed on 2006/12/05, the cracker stepped up his efforts to direct webspam to the Google-bot. In order to take back our site, we have taken the step of removing all the scripts on our site. We will restore static content as quickly as possible.

(Note: I think that 2006 should be 2008. I know I visited talkorigins.org several times in the last two years, last time being about a month or so ago.)

What is more alarming is 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.org or pandasthumb.org, period.

I eventually managed to find an excellent article (see the top of this post) using pandasthumb.org search tool. That led me to this non-technical article,
http://pandasthumb.o...onds-arent.html, and from there followed a link to the asa3.org article.

I found this on page 10 of Google's "carbon 14 RATE" search:
http://www.holysmoke.org/cre018.htm


So, what gives? Has Google itself been hacked?

This post has been edited by D H: 30 December 2008 - 03:41 AM
Reason for edit: multiple post merged

[Cap'n Refsmmat]

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 the 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.

[Griffon]

Thanks for your responses and the links to various sources. Much appreciated.

I am working my way through Kirk Bertsche's 9 page essay on the subject. Thanks DH for this link. Excellent. 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 reading 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 simply 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.

[Mr Skeptic]

Another thing I've heard from creationists is that fossils made by soaking samples in tar pits appear to be extremely old. Of course, the problem is that this process results in contamination with old carbon, making the sample appear older.

In the case of old samples with almost no C-14, even the tiniest bit of contamination would make the sample appear far younger. Always remember that C-14 dating is not a magical process; it is a measure of C-14 and the age interpretation depends on a few assumptions.

[insane_alien]

Mr Skeptic said:

Another thing I've heard from creationists is that fossils made by soaking samples in tar pits appear to be extremely old. Of course, the problem is that this process results in contamination with old carbon, making the sample appear older.

In the case of old samples with almost no C-14, even the tiniest bit of contamination would make the sample appear far younger. Always remember that C-14 dating is not a magical process; it is a measure of C-14 and the age interpretation depends on a few assumptions.

don't forget that the assumptions can be checked by analysing what the sample was found in. enough so it is possible to tell whether there was any severe contamination that would through the calculation way out of whack.

not only that but there are more methods than C-14 dating with which the results can be checked.

[Mokele]

It's also worth noting that C-14 is only useful for a bit more than 100,000 years. The vast majority of fossils aren't dated using C-14 at all, but other radioisotopes.

[Griffon]

Science has several very reasonable explanations for levels of modern carbon in very old samples. Although this satisfies the scientist, who for all sorts of other reasons quite reasonably assumes that these samples are truly old, it leaves enormous scope for the creationists to reinforce their followers' faith that the earth is young. I still feel that some definitive experiments in this area would be useful to test the various rational explanations for the c14 anomaly. I can see though that science has problems taking on creationists because of the perceived risk of lending credibility to their ideas. Bit of a dilemma there. Also as soon as one creationist idea is exploded, they just move on to another area where uncertainty in the science offers them the opportunity to mislead.

[D H]

Griffon said:

I still feel that some definitive experiments in this area would be useful to test the various rational explanations for the c14 anomaly.

Why? That begs the question that an anomaly even exists. What does exist are limits to the applicability of ¹⁴C dating techniques. Several of the test results touted by creationists were definitive experiments to assess those limitations. There is no arguing with young earth creationists. They are immune to logic and evidence.

[Griffon]

D H said:

Why? That begs the question that an anomaly even exists. What does exist are limits to the applicability of ¹⁴C dating techniques. Several of the test results touted by creationists were definitive experiments to assess those limitations. There is no arguing with young earth creationists. They are immune to logic and evidence.

Broadly speaking I agree with you. But, reading the experts' explanations of the "anomaly" read to me, as a non-expert in this field, like perfectly reasonable explanations as long as you accept the "old earth" explanation. If you don't, such dismissive arguments as 'the extra C14 could be due to uranium decay' leave enough wriggle room (uncertainty) for the creationist to thrive in. You're right though, I'm probably being naive in thnking they will be convinced. Even so, it is always good when creationists have been casting doubt in some area to be able to completely explode their reasoning.

This post has been edited by Griffon: 15 January 2009 - 08:47 PM
Reason for edit: add a word