Talk:Radiocarbon dating/Archive 1

Controversy

Carbon dating is often criticized in creationist circles as unreliable. I believe this is due to some cases in which the method yielded results that were later effectively disputed (possibly because the carbon dating made a constant cosmic ray flux assumption), but I don't know enough about this to be sure.

I think it would be a valuable addition to this article if some mention of these arguments were made, preferably with counterarguments. Anyone more knowledgable than I am willing to take this up? Great Cthulhu 16:29, 1 September 2005 (UTC)

The cases were not disputed because of cosmic rays, they were disputed because the creationists who cited them did not understand carbon dating. For example, they thought that dating the shells of living molluscs is relevant for evaluating the method. [1] --Hob Gadling 13:38, 29 September 2005 (UTC)

Further, I posit that if any of that ilk really wish to put up or shut up on their ideas, they can make a "What's wrong with anything that says the Earth is older than I say it is" entry, and failing that, they'll start shitting up this entry on their own accord. Part of the spooky-action-at-a-distance of NPOV is dialectical, isn't it? Opposing points of view will somehow find a stable equilibria or whatnot? Let's not violate that principle by trying to present the point of view of someone who wishes to destroy all understanding of radiocarbon dating with a false controversy. They'll be in here soon enough as it is. --Mayor Of France 18:49, 3 October 2005 (UTC)

Mayor Of France, I have yet to make up my mind on this (potential?) controversy. However, what is wrong for having people provide (valid) counter-arguments? Would it not be better for all parties involved to fight fair with sturdy facts, instead of engaging in "piranha attacks" as you have started to do? What benefit is there to raising the decibel level on this discussion? Surely, one would hope that the end result is that Wikipedia would come up with an article that can stand the test of time from rational people.

FWIW, no one has yet to posit the trollish "What's wrong with anything that says the Earth is older than I say it is?" argument. Surely, there are enough reasonable people here that will keep at bay those seeking to "...destroy all understanding of radiocarbon dating with a false controversy..." Are you saying that it is a false controversy simply because you have deemed it as such?? Perhaps you are of the opinion that Creationism/Intelligent Design advocates are predisposed to being disagreeable? If that is the case, it seems it has yet to present itself here. Please refrain from assuming the worst and give this debate a chance to be fair.

To date the only source of criticism of this technique has come from the young earth/creationism types. To elevate their unscientific attacks to the level of 'controversy' is to give them more status than they are due. As in most areas of science where their ideas cannot find traction, this group is now stooping to trying to inject the false impression that there is some internal debate in the field, thus providing a foothold for doubt. Doubt that they hope to exploit to foster their own interpretation of events. DV8 2XL 17:50, 10 December 2005 (UTC)

"what is wrong for having people provide (valid) counter-arguments?" Nothing. The problem is: there are no known valid counter-arguments, but a humongous heap of invalid ones. Every time a creationist (or ID person) presents a counter-argument (against evolution, natural selection, common descent, an old earth, or dating methods), it turns out to be based on ignorance or duplicity (hard to tell which). That's my experience. --Hob Gadling 19:36, 11 January 2006 (UTC)

Regardless of whether we agree or disagree on the validity of the controversy surrounding Radiocarbon dating, it is a fact that it exists (in a substantial amount). Therefor, a section should be added to the article detailing the various controversies. --Gregoryg72 12:53, 15 June 2006 (UTC)

I've noticed some incendiary comments in this thread opposing validation of young earth creationist arguments as controversy. Well, controversy is dependent on the existence of disagreement, not on the validity of an argument. No matter how invalid an argument is (in our Point Of View), there is a controversy as long as there is argument. And clearly, there is argument. However, that argument doesn't belong in this article, it touches on issues that are outside the scope of this article and the expertise of its contributors. We don't want to shift attention away from radiocarbon dating.

Rather than trying to describe the controversy in this article, it may be preferable to add a small section and paragraph marked 'controversy', indicating that radioactive dating methods are disputed by people who believe the earth is younger than it is shown to be. A more detailed discussion of this should be stored in a linked separate article named something like 'Radioactive Dating Controversy'. I believe Mayor Of France hinted at taking this approach.

How about the following for the paragraph:

"The accuracy of the radiocarbon dating method is disputed by those who believe the earth is younger than thus shown, particularly by Young Earth creationists. This is further discussed in the article Radioactive Dating Controversy"

This approach accomplishes two goals:

1.) It keeps this article focused on the issue at hand (radiocarbon dating, not religion). After all, the number 1 reason for young earth creationists to believe the earth is younger than radiocarbon dating suggests is that the Bible says so.

2.) 'Radioactive Dating Controversy' can be linked to from other articles (radiometric dating, radioactive dating) in a similar fashion, hopefully saving other wikipedians from constantly having to strip out NNPOV remarks.

Are there any reasonable arguments against this approach?

jdbartlett 01:49, 21 June 2006 (UTC)

Radiocarbon dating is science, and there is no controversy within science. Rather, there are people whose religious beliefs lead them to deny radiocarbon dating. Perhaps an analogy is useful: there is no scientific controversy that Earth revolves about the sun, but there are nonetheless some people whose religious beliefs lead them to deny this.

In other words, if you want to have an article in Wikipedia discuss the lack of belief in radiocarbon dating, that's fine, but the discussion belongs in an article on religuous beliefs. The discussion does not belong in an article on science (such as this one). If you started including anti-science religuous beliefs in scientific articles, you would have to do it for virtually all scientific articles: those that talk about Earth revolving about the sun, about the nature of the Moon, about the causes of winds, about how children are conceived, about ... just about everything. That is just not viable. Almost everything in science is disputed by some religion. So the place to describe such a dispute is in the article on the religion that disputes it.

—Daphne A 04:21, 21 June 2006 (UTC)

Thanks for your response. I agree entirely with your appraisal. That any 'controversy' is a religious matter and not a scientific one is exactly why I am proposing the creation of a separate 'radioactive dating controversy' article where the religious response toward radioactive dating can be handled. Once complete, the new article can be linked to from this ('radiocarbon dating') article so those seeking information on radioactive dating's effect on religion will know where to look. The place to describe the dispute (beyond acknowledgment) will indeed be in the article on religion that disputes it and not in this article.

The evolution article takes a similar approach. In fact, taking cue from the evolution article in labelling the linking section 'social and religious controversies' would be preferable as this would help the reader discern between religious and scientific controversy.

Does this approach seem reasonable or does it still require refinement?

jdbartlett 16:08, 21 June 2006 (UTC)

A separate article on radioactive (or "radio-isotopic") dating controversy is a fine idea. I can't imagine that anyone would disagree. My suggestion would be to then include a link to that article in the "See also" section of this article: others might suggest a different approach, but that is irrelevant for the writing of the new article. I hope you will do it!

—Daphne A 05:38, 23 June 2006 (UTC)

Thanks again for your response. I've started work drafting the article and hopefully should have something ready over the weekend. Interestingly, I discovered this while digging around: [2] I'm not sure how opinionated the deleted article was (probably quite, judging from the one-word comment "lol") but I'm still worried my article will suffer the same fate based on the number of votes to merge or delete controversy on... by reasoning that radiometric dating is treated in its own article. I've started work on an anticipatory Justification section for my article's Talk page which will mostly reiterate what we've discussed in this thread.

jdbartlett 09:40, 23 June 2006 (UTC)

Perhaps the way to do it is to entitle the new article "Religious-based controversy over radiometric dating", or something similar. There definitely is a religuous controversy, and an inclusive encyclopedia should mention this. Similarly, there were apparently some native Americans who, for religuous reasons, didn't want certain people to go to the moon; again, this has nothing to do with science, but it is a religious belief that deserves mention in an inclusive encyclopedia, even if most people (including me) find their religuous beliefs silly. The new article could even take a sort of anthropological approach (just as an article on the natives and the moon might).

—Daphne A 12:14, 23 June 2006 (UTC)

I saw DaphneA's comment above "Radiocarbon dating is science, and there is no controversy within science." and it reminded me of an article I read recently, which can be found at http://www.crichton-official.com/speeches/speeches_quote04.html. The article is called "Aliens Cause Global Warming" which is rather tongue in cheek, so don't let it scare you off. I myself am a student of history, not science and I am content to wade in the shallow end of the intellectual pool with my water wings and PFD on. Nonetheless, I can't agree with the contention that there is no controversy within science, as this article clearly illustrates. Further, in many, if not most, areas of science, in particular physics I believer, we are still hampered by an inability to know absolutely everything. This of course means that in many instances we will only achieve the 75% solution, when the little tidbit of information we lack could lead us to completely different conclusions. While I am at a loss at this late hour to provide an example, I am quite sure that through the ages there have been a myriad of "facts" that science agreed upon which were later unproven. This leads me to believe that any contention that tere is no controversy within science is patently false. Of course this discussion is not a debate on the existence of controversy in science but on whether or not a section of controversy should be included in an article on radiocarbon dating. If the world truly lives in a balance, there will never be a theory without a counter-theory. The controversy surrounding radiocarbon dating is just as much a part of the theory as the science is, and should therefore be included for the reader to make up their own mind, placing each in context with the other.

Sorry for the ambiguity. What I meant was that there is no controversy within the science of radiocarbon dating. Also, there actually are controversies about radiocarbon dating within the science (e.g. location dependencies), but the specific controversy being discussed here is religious. —Daphne A 07:04, 18 July 2006 (UTC)

Can you please give a list of the "radiocarbon science controversies", and also clarify what do you mean by "location dependencies"? Please, include relevant references so we understand what we are talking about. --Jclerman 07:51, 18 July 2006 (UTC)

A good place to start is with F.G. McCormac et al., "Location-dependent differences in the ¹⁴C content of wood", Radiocarbon 37: 395–407. Then use Google Scholar (or Science Citation Index) to find papers that cite that. —Daphne A 09:14, 18 July 2006 (UTC)

dating conflicts

Please:

• Propose in this page the examples you want to be considered.
• Include possible rebuttals and/or explanations already.published for each case in scientific publications (i.e., not in Newsweek).
• Do not include moon rocks and other samples not datable using radiocarbon.

Jclerman 06:09, 7 February 2006 (UTC)

The stuff about molluscs and moonrocks recently removed from this article has just been given its own article, Controversy on Radiometric dating, again with none of the counter-evidence. It is therefore completely POV. I remember reading that the snail shells were found to come from an ecosystem fed from ancient aquifer-water, but I don't know the source, and I'm not knowledgeable enough to un-POV the new article. Just letting people here know. --Squiddy | (squirt ink?) 14:10, 7 February 2006 (UTC)

I've seen the talkorigins answer on that very subject, it actually seems very plausible, but that aquifier water isn't the only thing those snails could of gotten C14 from, unless that water was like diluting most of the water shed and everything around it or something, which I don't think the talkorigins page mentioned. Personally, i'd like to see some of the examples on some of the more famous fossiles of Neanderthals since those are often the most famous things to have controversy over, the talkorigins archive had a very....interesting answer to conflicts on one of those I think, in which it claims that since bones are porous, of course the C14 dates would be all messed up as it would leech into it continually. Which of course begs the question how can any C14 dates of any bones be reliable, I understand how you can use dating methods on the land around it, but then all those other methods have to of been stable for thousands of years which is often very unlikely....but that's just my opinion, in the end, some more things on Neanderthal and other supposed human ancestor dating would be nice. Homestarmy 14:32, 7 February 2006 (UTC)

Risking to be rude, let me ask you whether you have read my response to you in this same page, above, here repeated: All your questions, critiques, and objections have been answered and discussed at length in the references given in the article. The detailed explanations given there are much more complete and thorough than we could do in this column. Also, if there is a radiocarbon dating lab in your locality, you probably could join an organized group visit and get a direct view and understanding of the method. In particular they could "walk you" through all the chemical and physical aspects of sample decontamination. analysis. computation, etc using data from real samples so you could compute yourself their ages and so get an "insider's view". Jclerman 01:22, 29 January 2006 (UTC)

Wha? No, I was earnestly suggesting this article contain some more things about it, you asked for ideas, I was giving one, and giving some background information on my opinion, but simply ended by re-iterating that I thought it would be a good thing to put into this article, as those kinds of examples are popular topics. You told me to go get some real reaserch on C14, so I went to talkorigins and looked stuff up, I don't know any carbon 14 labs near my area and I don't see why real information on C14 dating must only be in carbon 14 labs. Homestarmy 16:06, 7 February 2006 (UTC)

I do hope useful ideas and text are added. My suggestion to visit a lab is because I don't know what's your background and experience in the sciences and seeing the procedures and samples is equivalent to hundreds of pages that don't belong here. If you can get hold of a chemistry instructor of a high school or college: ask her/him to show you how to extract the mineral part from bones and shells, until the collagen matrix remains. Then the reply to your questions about bones and shells dating will click. Jclerman 20:17, 7 February 2006 (UTC)

Well we have a great chemistry teacher at a great private school but the problem is we don't have a great budget for a great chemistry lab, I think we might of blown most of the funds on silver(II) nitrate anyway :/. But are you saying talkorigins isn't the famed repository of evolutionary knowladge that people sure seem to make it out to be? I mean it seems like a very straightforward site with increadible detail, and the answers seemed very straightforward and earnest and it seems like it was worked on for a very long time, though they did give answers which seemed deceptively simple and short along with deceptively wrong to me at least.... Homestarmy 02:12, 8 February 2006 (UTC)

This topic is now being continued in Controversy on Radiometric dating and its corresponding discussion page.Jclerman 15:41, 7 February 2006 (UTC)

That page dose not exist now and I see no reason to create it. The discussion is doing just fine here. Lotu 23:35, 22 March 2006 (UTC)

Reliability

This article should also mention the questions of reliability of carbon dating. Until this is done, (I don't think I know enough about it to write it myself) I will be placing a NPOV dispute notice on the page. AH9 15:50, 11 March 2006 (UTC)

Reliability seems well covered in the sections Measurements and scales and Calibration. Or were you just referring to creationist objections based on religion? Removing tag. Vsmith 16:07, 11 March 2006 (UTC)

I was referring to the objections based on the fact that we don't have reliable carbon samples from as long ago as some objects are dated to compare the levels with. Replacing tag. AH9 16:14, 11 March 2006 (UTC)

I can't figure out what you are trying to say here. Can you please be a little more clear. Guettarda 16:15, 11 March 2006 (UTC)

Agreed. How about some refs on this. Radiocarbon dating has been verified by a variety of other dating methods (radiometric as well as others such as dendrochronology). Vsmith 16:30, 11 March 2006 (UTC)

Radiocarbon dating requires several assumptions.

1. We know how much Carbon-14 and Carbon-12 were in our original specimen.

True, if you mean before the specimen died or was taken off the exchange system

2. No Carbon-14 or Carbon-12 was added or lost during the time this fossil died to today.

False. We measure the decrease of C-14 in the sample to determine its age.

3. God had nothing to do with it.(This I believe is the majority view, but usually necessary to determine something to be really old.) I'm just curious. How does radiocarbon dating produce millions of years (e.g. dinosaurs) if Carbon-14 totally decays within about 50,000 years?

Off topic. Science is faith independent.

False. C-14 does NOT date dinosaurs.

True. The maximum C-14 age detectable is about 60,000 years.

And isn't coal (which has never been found without Carbon-14) supposed to have existed several hundred million years ago according to the Geologic Column?

False. If fossil coal was found with detectable C-14, it was due to contamination with modern organic matter, usually during sampling.

True. And again its age is NOT measurable with C-14.

Is there some place where we have found the whole Geologic Column complete and intact with all its index fossils?

See geology textbooks.

I am just curious if someone can enlighten me to the answers to these questions.Alisyd 16:19, 13 April 2006 (UTC)

Done. See above. Jclerman 16:58, 13 April 2006 (UTC)

I looked up how radiometric dating is done. Correct this is if I'm wrong. Carbon-14 decays into Nitrogen-14. In dead specimens, C-14 decays into N-14 halfway in about 5,730 years. So in about 11,460 years there should be 1/4 of the original amount. After 50,000 years C-14 is virtually impossible to detect. However the assumptions remain. 1. We know that there was no daughter material(N-14) in the original specimen.

It doesn't matter. It might have been, depending on the composition of the sample but we don't look for it in the sample to be dated. We only look at the C-14 activity or concentration.

2. Decay rates have always been the same.

Correct.

3. The system was closed and so no parent or daughter isotopes were lost or added.

Production rate and mixing rates have varied but are corrected by calibrating the scale (see the article).

Science is testable and observable. No was there when the object died so no one could know whether these assumptions are true or not.

There are datable materials (such as tree-rings) which recorded the events.

As for the geologic column in textbooks that is the only place on earth where one can find it. I have also heard that index fossils like Coelacanth have been found alive.

Then they were not fossils. Scientific observations are testable and verifiable. After the hypothesis are corrected, we progress towards a more correct knowledge.

Lastly, I noticed it was interesting that first you tell me C-14 is measured by its decay rate but if coal is found with it then it must have been contaminated. How do we know that these fossils haven't been contaminated? Alisyd 17:46, 14 April 2006 (UTC)

We know about the degree of contamination with admixture of modern carbon by cleaning physically and chemically. Progressively cleaner samples give radiocarbon ages which approach the real age.

Jclerman 18:54, 14 April 2006 (UTC)

Is there any chance that someone could add a mass transfer (general transport processes ) to the discussion. Just because the object to be dated is buried or not transport processes continue around the object. Is carbon-14 being leached out of the object at a faster rate or slower raten than the same process for nitrogen? Doesn't this have an effect on the ration of carbon-14 to nitrogen? 12:08, March 24, 2007 Godzilla1138

Not a chance. You can study solid diffusion processes or whatever you think about and write it in. The ratio [sic], not ration [sic], of carbon to nitrogen is irrelevant. When counting C-14 atoms one doesn't care about the nitrogen. And the chemical and physical processes of carbon 14,, like leaching or similar, as compared with carbon 12 are controlled by the well studied isotope fractionation effects which are corrected for when dating. All variations and calibrations were described not in Libby's works (ca 1950) but in the "12th Nobel Symposium" (1970). I suggest you read it. You'll find detailed answers to your questions. The article in the wikipedia is not intended to be a "how to do it tech manual". Regretfully some of us have limited access to physical libraries either by geography or by health reasons. Your contributions will be greatly appreciated but you'll have to do some leg work. Incidentally, much of the critiques of Libby or about Libby in the discussions are irrelevant. Little has been dated using Libby's techniques. It was Hesel de Vries who established the modern basis of radiocarbon dating, expanded upon in the mentioned Nobel Symposium. See Paul Damon, "online" electronic mail interview, October 29, 1998. Interviewer Theodore Feldman in [3]

Jclerman 21:26, 24 March 2007 (UTC)

What is being dated?

The BBC reported that the giant tortoise that recently died in India (Adwaitya) was going to be carbon-dated in order to determine its precise age. (This was reported by BBC-TV; the claim is not repeated in the on-line version of the BBC's report that is linked to from the Adwaitya article above). This sounds strange to me: I thought that what this method dates is the moment of death of a creature, not its moment of birth. The article does not seem to address this question. JanCeuleers 09:56, 25 March 2006 (UTC)

The BBC Online says, indeed, that: <<The shell of Adwaita, an Aldabra tortoise, will now be carbon-dated.>> It means the oldest parts of the shell Jclerman 10:20, 25 March 2006 (UTC)

And hello? thats why carbon dating measures the DECREASE of 14c if a fossil is tested and has zero 14c then what was it contaminated with?? Nothing? that means its at LEAST 50,000 years old as opposed to 6,000 which is most creationists beliefs.

Some conventions regarding radiocarbon results

(title revised)

• New section moved here due to internal and external inconsistencies, unexplained steps, and confusing typos and errors. Discuss here revised versions. Jclerman 07:13, 26 March 2006 (UTC)

Clerman and I are rewriting this so what you see is the version being progressively revised. Feel free to join the process if this would interest you.Dave 02:17, 28 March 2006 (UTC)

Opening of discussion

Hello Jclerman. I'm glad to see there is a watchdog on the article. I note your previous participation in that capacity. But, let me open by saying that I think the article needs more than just a watchdog. For the moment I'm interested mainly in calibration. The article doesn't really tell you what is going on in calibration. It has no mention of bristlecone pine or Irish oak, does not actually tell you in plain English what a calibration curve is or mention any international efforts to agree on a curve. It does not tell you what the formats of a calibrated date mean. A few vague generalities about calibration are all you get. Now, you can find SOME tutorials and expansions in the external links. I just thought this section ought to have more explanation and some pointers. I invite you or anyone to clean up the material below or provide a different write-up. If you do that, I will follow up on what YOU say (or anyone says). If not, why don't you begin by stating your philosophy if different? If we are going to clean up what I wrote below, then please state what internal and external inconsistencies you find, so we can fix it. Fair enough?Dave 12:18, 26 March 2006 (UTC)

Revised proposed addition

<< There are many conventions and techniques of deriving radiocarbon results. Once the results have been obtained, they must be stated in a way that is comprehensible to those who rely on them to date the historical (or prehistorical) phenomena in which they are interested. Archaeological and other publications therefore make use of a standard convention, which you may find explained in simple terms in the "Layman's Explanation..." web page linked under "External Links" below. It is being published by the University of Oxford Radiocarbon Accelerator Unit. This convention has varied somewhat historically, as is explained below. A brief summary follows.

A raw, or uncalibrated radiocarbon date is stated as years before present (BP). Seeing a BP date, the ordinary reader will immediately want to subtract 2000 years to obtain a date BC (or calculate the date AD); e.g., 9000 BP appears to be 7000 BC. For rough estimates in general reading and quick calculations of the dates of archaeological periods, which are very imprecise, this method is useful, provided the date is not a raw radiocarbon date. The latter needs to be calibrated to obtain the true date indicated by the results. In the example, 7000 BC is not calibrated and could be 10-15% in error.

Calibration can be as simple as a look-up on a graph of raw dates BP on the vertical, or y-axis, and calibrated (cal) dates BC or AD on the horizontal, or x-axis, such as the "calibration curve" shown above in this article. The term, calibration curve, refers primarily to the jagged line shown in the graph, and secondarily to the whole graph. One looks on the vertical axis to find the BP date to be converted, traces horizontally across to the calibration curve, and then traces vertically to the horizontal axis, where the calibrated date can be read.

This is supposed to be an encyclopedia, not a laboratory manual. It is our job to explain how and why published calibrated results can be ambiguous or far less precise than the raw laboratory value suggests to help users undestand them and interpret them correctly, but not to teach how to use a curve or software package. - Axel Berger 09:02, 30 March 2006 (UTC)

More typically, a computer program performs a virtual lookup using algorithms and data stored in the program and in memory. You enter the raw date through a field in the screen and the program displays or prints the calibrated date. The external links below point to sites, such as CalPal, where you can obtain a calibration.

The calibration curve itself is the result of decades of measurement and research. To obtain points on the curve, researchers took radiocarbon dates on samples whose dates were known by other methods, such as dendrochronology. Some very long-lived trees; e.g., California bristlecone pine, offer a continuous series of known dates over thousands of years. Once the points were known, the lines could be created by various methods, such as statistical curve-fitting (regression analysis). For such a span of years, it was necessary to use different methods for different sections of the graph.

All measurement is subject to some variability; that is, if you take several measurements of a quantity, they will be found to vary at random. Statistics characterizes this variation by calculating a mean value and a spread of deviations from this value, which are called "errors". You can then calculate a standard deviation (STD), represented by the mathematical quantity, σ.

---

end revised part of section

For purposIt has been called "the probabilistic approach.

es of calibration, the BC date is stated with a tolerance, such as 3450±50 years BP. This is not a mechanical tolerance, but a statistical one; that is, measurement took into consideration the variance due to a number of factors, including error, and a standard deviation (STD or σ) was calculated. In the example, the 3450 represents the mean and the 50 is the σ. In fact valid possible dates might exceed 3500 or be less than 3400.

A normal (random, Gaussian) distribution is now assumed, which is represented by a bell-shaped curve on a graph of numbers of standard deviations on the x-axis versus probability or frequency on the y-axis. In this kind of distribution, 68.26% of the dates or possible dates will be found within 1σ; that is, between 3400 and 3500. This is called the 62.26% confidence interval, because you are "62.26 confident" that a given date will be in this range. 95.46% of the dates are at 2σ; that is, the confidence limits are 3350-3550.

One now imposes the x-axis of the bell-shaped curve on the y-axis of a graph of calibrated dates BC (x-axis) versus raw dates BP (y-axis). On such a graph, the "calibration curve" is a line of plotted points, the coordinates of which are dates BC and BP. In contrast to the one shown above, the curve is typically quite irregular, bending up more than once so as to give two or more possible ranges of BC dates for a given range of BP dates. Also, the line is usually double, representing an error tolerance.

A confidence interval of BP dates translates to a confidence interval of BC dates. However, there will be more than one confidence interval of BC dates if the calibration curve allows more than one range. Typically the normal curve for BP dates is shown based on the y-axis, which develops into a curve of one or more peaks for BC dates on the x-axis.

A single radiocarbon date is fully stated therefore as in the following example:

3450±50 BP

68.26 probability (or confidence)

3650 (86%) 3750 BC

3825 (4%) 3875% BC

In this fictitious case, the range corresponding to 3400-3500 BP uncalibrated is either 3650-3750 BC cal. or 3825-3875 BC cal. The number in parenthesis states the probability associated with each range; that is, 86% of the dates will be found in the first range and 4% in the second. Sometimes fractions are used for percentages: .86, .04. One can estimate by picking the highest-frequency range and assuming that the others are error variations, or taking the whole range, peaks included.

Prior to this method, the intercept method of Pearson and Stuiver was commonly used; for example, Gimbutas used it in such publications as The Civilization of the Godess. In this method, the x-intercepts of the 1σ interval are taken as end points of a range stated, for example, in this format: 7050 (6771, 6742, 6716) 6568. The numbers in parentheses are the most probable dates of the peaks of the ranges present. This method fell out of use because it did not indicate any of the probabilities. >>

About the additional text

My involvement with the initial radiocarbon dating article in the Wikipedia has been until now restricted to the section on measurements and scales, computation of ages and dates, captions to the graphs, and discussion of some of the terminology. In my opinion, the other sections still need to be revised.

Much of the material in the references and/or external links should also be incorporated into the article, especially the contributions of Hessel de Vries (see discussion page) and global warming.

Also, it is my opinion that the dendrochronological contributions are better discussed in the dendrochronology article.

You're OK. A good professional critique. It deserves me to pay attention. ... You know what Clerman? I had some other comments. But, looking at it again, it seems to me now they are not fair. If you want to see them and did not already you can look back in the discussion history. Try not to get too angry. Let's just get on with this.Dave 01:35, 28 March 2006 (UTC)

PS. ... overall, your message appears to me to be that the write-up is not user-friendly. It assumes too much. I can emphathize with that. One can be too concise. ... As for the graphics, that is not my fault old boy. I searched Wikimedia high and low for some graphs and could not find any. have you got any? The references I gave have some great ones but they are not ours. ....

----- Introduction to the comments on the recently proposed text -----

In particular, concerning the recently proposed additional text, each one of its several statements is here followed by my questions and comments, indented. These should aid to recast the text in a more parsable version. I should be glad to clarify and/or comment on these and/or on further iterations of the text. I have followed the seemingly harsh model followed by the editors of my first radiocarbon papers. They surely helped me to draft papers accessible both to lay readers and specialists.

... though some degree of rigor is desirable, we do not want rigor mortis. Creativity produces the best writing. It seems to me this should be written more with the general public in mind. The readability you described as "parsability" is a good idea.

----- Text with intercalated comments -----

Professional radiocarbon dates are currently published according to a convention, which is stated in the references given under External links, and is summarized briefly in the following.

The adjective "professional" seems superfluos.

Done. You mean superfluous I believe.

How would the reader identify the here summarized "convention(s)" amongst the many published in the references?

That is not what I meant, but, following our new source (which I added) I did clarify that in rewriting. There are not many conventions in stating the final form of the date.

It has been called "the probabilistic approach."

Called by whom? Is there a need to name the calibration approach? If yes, why? A citation would be helpful so the reader can find it within the publications.

OK. Done. Will mention in rewrite. The need comes from there having been more than one approach.

The raw, or uncalibrated date, is years before present (BP), where "present" is not today's date, but is 1950, as is explained above.

No date "is years". The meaning appears to be that a date "is measured, expressed, or given in years".

My phrase is of the formula, "the time is hours, minutes and seconds", "the area is square km". If you didn't want to be quite so brief you would use "in": "The date is in..." ... It's correct, but the rewrite makes the question go away.

What is such offest needed for?

That is quite obvious in the context. But, the rewrite changes the need for such a statement.

It states that it is good enough. For what?

Accepted. I elucidated that better.

The radiocarbon dating method does not date only BC dates, but also AD dates.

Accepted. My interest covers mostly BC so I did not notice.

For the purposes of calibration, the BC date is stated with a tolerance, such as 3450±50 years BP.

Again, radiocarbon also dates AD dates.

Accepted.

Tolerance? No need to introduce a new term. The correct term "interval of significance" should have been used above and also here.

Well, if y-axis is above their level then interval of significance surely is. I was trying to tie in to what they already know, not "introduce a new term." Tolerance is a general English word not a special term. They've already seen tolerances in plus or minus form. They might conclude that this is a tolerance. They have to be told what it is. I will compromise ... however. If we use interval of significance then we have to explain what it is.

This is not a mechanical tolerance, but a statistical one; that is, measurement took into consideration the variance due to a number of factors, including error, and a standard deviation (STD or σ) was calculated.

Again, not tolerance but interval.

What are the factors not included in the term "error"?

Any physical variability that can't be corrected. The "error", in addition to reflecting random variation of sampling, also serves as a fudge factor for them. So they are included in the "error" in that sense. I'm not going to write you an essay here or try to place one in the article, so I will just end the concept right now.

OK, the STD was calculated, but is the interval given equal equal to one STD?

What?

In the example, the 3450 represents the mean and the 50 is the σ. In fact valid possible dates might exceed 3500 or be less than 3400.

Clearer than "the 50 is the sigma" is "sigma is equal to 50".

You think so? I don't. We are expanding the list items of the example, which has already been stated, so sigma is not the subject, but the number 50 in the example is. Doing it your way is less precise, so the reader has to ask, "now what sigma is that?" and guess that the sigma is the 50.

The values lack units.

It is only necessary to states the units the first time or where there is any question.

A normal (random, Gaussian) distribution is now assumed, which is represented by a bell-shaped curve on a graph of numbers of standard deviations on the x-axis versus probability or frequency on the y-axis.

Horizontal axis or abscisae is more correct since there is no named x-variable. Similarly, vertical axis or ordinates is to be preferred to y-axis. The scale of the horizontal axis should be "number of ..." rather than "numbers of ..."

Anyhow, it seems akward to describe a graph rather than to show it. Just linking to the relevant Wikipedia article seems more appropriate.

I'm afraid we are pioneers here. I couldn't find a Wikipedia article with an appropriate graph. But - not to fear - I just noticed that the graph in the current article has wiggles. At that scale the curve looks straight but maybe an expansion is possible. Ok on the number instead of numbers. By the way, akward is spelled awkward. And you do have to tell them what they are looking at. Too bad we do not have much to look at anywhere. Rome was not built in a day. How come you are not questioning normal and Gaussian? Not many people would know what they are.

In this kind of distribution, 68.26% of the dates or possible dates will be found within 1σ; that is, between 3400 and 3500.

All results of measurements should be accompanied by the corresponding units. E.g., years BP.

No, not if they have been stated and are obvious. If you are talking about a calculation involving amps or ohms you don't have to keep repeating amps or ohms. That sounds like an ancient Egyptian formula in funeral texts. It seems to me, you are quoting some technical journal or professorial standard. But this is Wikipedia, for eveyone. Readable English is the standard.

This is called the 62.26% confidence interval, because you are "62.26 confident" that a given date will be in this range. 95.46% of the dates are at 2σ; that is, the confidence limits are 3350-3550.

From where come the value of "62.26%" and "62.26 confident"?

That's an error, my friend. Of course it should be 68.26.

Why do you jump to 2 sigma? How do you derive the 3350-3550 interval for what you seem to imply is a 2 sigma interval?

"Although it is conventional to quote raw radiocarbon results with +/- 1σ errors, users can choose to use the 95.4% confidence level for calibrated dates if they wish." The Bowman source, page 49. In this example if 1σ is 50 years then 2σ is 100. 95.4 % of the possible dates will therefore fall within 100 years of 3450.

Again, units are missing.

I'll evaluate the necessity when I rewrite it.

One now imposes the x-axis of the bell-shaped curve on the y-axis of a graph of calibrated dates BC (x-axis) versus raw dates BP (y-axis).

What do you mean by "ïmposing" an axis on another axis? If you imply an operation that can be better explained by an illustration, either include such an illustration or refer to where the reader can see it.

Hey, I wish that I could. Perhaps I can reword a bit to make up for the lack of graphics.

Notice again that the calibrated radiocarbon dating scale includes both the BC and the AD ranges of the Gregorian Calendar.

OK

On such a graph, the "calibration curve" is a line of plotted points, the coordinates of which are dates BC and BP.

In fact, it is a line obtained by statistical smoothing of the data ("points").

OK. Point taken, but not necessarily as you say. "Straight lines are usually adequate, but are not representative of a natural process: the alternative is computer-produced curves called spline functions." The Bowman source, page 46. Why don't we leave the topic of how up to the laboratory. Maybe it could go in a more specialized article. I will take out "plotted."

In contrast to the one shown above, the curve is typically quite irregular, bending up more than once so as to give two or more possible ranges of BC dates for a given range of BP dates.

Isn't the curve intended to be a calibration curve?

I don't know what you mean there. The statement is wrong anyway, because if you look closely at the curve you can see the wiggles in it.

If it does not represent the kinks in the "real" curve, ask the author of this one to correct it and, meanwhile refer to a suitable curve published elsewhere.

What do you mean? Didn't you see it? I don't know anything about it that you don't know. The one given looks professional to me. Its OK. My statement is wrong. Also, I doubt we want to be in the position of saying, for the illustrations for this article, see A, where A is some remote and inaccessible work the reader will never find or be able to access, and if he/she did, would have to spend a week looking for it. We will just have to make do until curves show up. I think they will.

Also, the line is usually double, representing an error tolerance.

If a line is double, it is two lines. And they would represent the "confidence interval" rather than the "error tolerance". Not only for the sake of correctness but of internal consistency with the language used in the next sentence.

I'm trying to use language the ordinary reader would understand. But now that I think about it, why don't we just leave that out, as you only see the two or three lines in textbooks? I envisioned this as a few paragraphs giving the reader a lead-in.

A confidence interval of BP dates translates to a confidence interval of BC dates.

Again BC dates rather than BC/AD dates.

OK

However, there will be more than one confidence interval of BC dates if the calibration curve allows more than one range.

I guess you try to describe what is impossible to understand, without a graphic illustration, by somebody who does not know what is a non monotonic function and the kinks in its graph.

I suppose so. But without this piece of the puzzle, just forget the whole section, as the calibrated dates are the target concept. The situation is mitigated by the external links. That is where they will go next and they will find graphics there.

Typically the normal curve for BP dates is shown based on the y-axis, which develops into a curve of one or more peaks for BC dates on the x-axis.

Again I guess you try to describe what is impossible to understand, without a graphic illustration, by somebody who does not know what is a non monotonic function and the kinks in its graph.

For somebody that has never carried on such a calibration, "based on the y-axis" is not understandable.

A calibration is only a lookup, no matter how complicated the process of obtaining the curve is. You look up BP and you read BC or AD. Anyone can read a graph if told what to look for. Maybe I can elucidate a little.

A single radiocarbon date is fully stated therefore as in the following example: 3450±50 BP

68.26 probability (or confidence)

3650 (86%) 3750 BC

3825 (4%) 3875% BC

A % sign is missing for the 68.26 value.

OK

It lacks to identify which dates are raw and which ones are calibrated. Since in other paragraphs calibrated dates appear expressed in "BC cal" units, use of plain "BC" appears not to be the result of a calibration.

OK

Without a graph the uninitiated reader can not understand how the ranges and their probabilities are derived.

Well. We seem to be at a crisis point. Two paths lie before us: 1. Not include a section without a graph. 2. Find an appropriate graph in the external links. What do you think?

In this fictitious case, the range corresponding to 3400-3500 BP uncalibrated is either 3650-3750 BC cal. or 3825-3875 BC cal.

Why now the 3400-3500 BP range?

1σ, don't you know?

Why without a probability value?

It seemed obvious from the write-up, but we can throw it in.

Without a graph the uninitiated reader can not understand how the cal ranges and their probabilities are derived.

Why two ranges? Does "either or" mean that any one of both intervals is valid?

Didn't I explain that in the section? The interpretation of the calibrated date is up to the archaeologist or scientist who is trying to use it. It's only a tool. He might reject it altogether pointing out that it is totally contrary to the chronological structure provided by known historical dates.

Has cal been defined as calibrated? Where?

OK Should be like this at the beginning: calibrated (cal)

The number in parenthesis states the probability associated with each range; that is, 86% of the dates will be found in the first range and 4% in the second.

Without a graph the uninitiated reader can not understand how the ranges and their probabilities are derived.

He doesn't have to know all the details, only what it means. This has to do with the crisis point I mentioned.

"Values within parentheses" is the usual expression used instead of "numbers in parenthesis".

Bunk.

Sometimes fractions are used for percentages: .86, .04.

86% is identical to .86, since percent=1/100

4% is identical to .04, since percent=1/100

Anyone literate enough to read the article will know that.

One can estimate by picking the highest-frequency range and assuming that the others are error variations, or taking the whole range, peaks included.

One can "estimate" what? Dates? Ranges?

Archaeological or other periods associated with the material from which the dates were obtained. We can explain that more.

What does "error variations" mean? How do they affect the ranges and peaks?

Without a graph the uninitiated reader can not understand what "highest-frequency range" and "peaks" mean and how the range and peaks are determined.

Don't agree.

Prior to this method, the intercept method of Pearson and Stuiver was commonly used; for example, Gimbutas used it in such publications as The Civilization of the Godess.

Using "this method" in consecutive sentences might confuse the reader as to which method each statements refers.

I'll take look at the rewrite to see if the criticism still applies.

An explanation and a reference for the "intercept method of Pearson and Stuiver" are missing.

OK. These names are from Bowman.

A reference or link to the cited Gimbutas's work is missing.

Ok. I thought I had it but I will check.

In this method, the x-intercepts of the 1σ interval are taken as end points of a range stated, for example, in this format: 7050 (6771, 6742, 6716) 6568.

Using "this method" in consecutive sentences might confuse the reader as to which method each statement refers.

Without a graph the uninitiated reader can not understand what "highest-frequency range" and "peaks" mean and how the range and peaks are determined.

The numbers in parentheses are the most probable dates of the peaks of the ranges present.

Without a graph the uninitiated reader can not understand what "most probable dates of the peaks of the ranges" means and how the range and peaks are determined.

Disagree. Maybe a few more words of explanation.

The expression "values within" is preferred to "numbers in" in this context.

Maybe by you.

This method fell out of use because it did not indicate any of the probabilities.

Using "this method" in consecutive sentences might confuse the reader as to which method each statement refers.

No way. They all refer to the same method. But, it is repetitious.

A citation about the "falling out of the method" would be desirable.

Not necessary. Everyone can see how it is done now and how different that is from the prior approaches. But, I'm relying on a criticism (I think it is Bowman, who goes into the history) that the dates only do not give the probabilities, and so the other method is now preferred. I can find it.

Jclerman 08:55, 27 March 2006 (UTC)

Well, J. Clerman, I have some constructive criticism of your approach. We are not operating according to the model, "I'm OK, you're OK." I have become the student and you the professor. You are in effect correcting and criticising my paper. You are applying the model to me that was applied to you.

This is not a classroom. I can stand to be corrected no doubt. But this is a team effort. The article isn't "my article" and I don't much care what grade you give me. This is "our" paper, so to speak. Feel free to take an active role in writing it. It is a more risky effort, as you open yourself up to criticism and correction. It is safer, certainly, to contribute nothing but comments on the contributions of others. I know you worked on the article before. Why not work on it now? Not enough time? Isn't it worth the effort? There is a certain school of Wikipedian, I have observed, that stands off and delivers often nasty comments under the pretext of being the specialist clique that decries the amateur efforts of the great unwashed. That's the easy way out, isn't it? Leadership is a lot of work. Get back to work, Clerman.Dave 04:38, 30 March 2006 (UTC)

Cambridge half-life

"Originally a Carbon-14 half-life of 5568±30 years was used, which is now known as the Libby half-life. Later a more accurate figure of 5730±40 years was determined, which is known as the Cambridge half-life."

If these are measurements then we can't say one is more accurate than the other without presuming some value. You can't presume values for measurements.

Also, if this statement is referring to the error bars then a number with an error bar of ±40 is NOT more accurate than a number with a smaller error bar however it is less precise, that is all.

According to the above statement the Cambridge half-life is simply less precise. The above statement should be fixed.

Unsigned, by 68.70.247.219 00:54, April 15, 2006

A better instrument or method gives a more accurate result.

A measurement can be more accurate and less precise.

The quoted statement is correct. It might be incomplete vis-a-vis the precision of 40yr vs 30yr, which is, however, not relevant vs 5700yr.

Jclerman 09:34, 15 April 2006 (UTC)

Plural of 'half-life'

What is the plural of half-life? I thought it was half-lifes because the concept is one individual half-life many times over, sort of (it's hard to explain that), but apparently somebody else wants it to be half-lives, with a v. Can anybody find an official answer? J. Finkelstein 18:58, 9 May 2006 (UTC)

A quick and non-scientific check in Google shows an overwelming difference:

• half-lifes: 57,500 hits
• half-lives: 2,980,000 hits

What makes you think anyway that the plural of "life" would not be "lives", even when preceded by half? −Woodstone 19:40, 9 May 2006 (UTC)

It depends on your beliefs[sic]. And on the physics. Radiocarbon and each other radioactive isotope have, each one, a single one half-life which might have several values adjudicated to it depending on measurements. Several isotopes have different half-lives. 207.195.242.7 00:20, 10 May 2006 (UTC)

Well, what's the plural of court-martial? English is funny, that's all I'm saying :D. If it's half-lives then it's half-lives. I don't know why I thought it was like (half-life)s. Whatev. J. Finkelstein 04:30, 10 May 2006 (UTC)

It's IMHO

1. radiocarbon (Libby vs Cambridge) half-lifes
2. radiocarbon and tritium half-lives

69.9.31.103 07:38, 10 May 2006 (UTC)

Discourtesy by Jclerman

..... Daphne A 05:57, 13 June 2006 (UTC)

Text deleted because you deleted my reply to your comments. That was the discourtesy. Jclerman 14:04, 26 March 2007 (UTC)

Unexplained deletions

The two references to the work and legacy of Hessel de Vries are missing:

Hessel de Vries, at the University of Groningen furthered the detection methods and applications to a variety of sciences (cf Engels). He has been called "the unsung hero of radiocarbon dating" (cf Willis).

BTW, they were included after an editor's request for balance vs Libby.

Jclerman 08:53, 13 June 2006 (UTC)

You are right, of course, that the Willis reference should not have been deleted (I had missed that it was cited in the body of the article). I'll restore it.

Regarding the Engels reference, this is actually in Dutch, which is read by a very tiny percentage of readers of en.wikipedia.org. So unless the reference is really critical, or an English translation can be found, I think it would be better to change the article to no longer reference it.

—Daphne A 09:48, 13 June 2006 (UTC)

It's so critical that there is a long discussion about it, a few sections about this one, under Hessel de Vries. Deleting the topic will destroy the article. Jclerman 09:57, 13 June 2006 (UTC)

I was not suggesting deleting the topic, just the reference to Engels (i.e. 11 characters: "(cf Engels)"). (If anything, I think that the topic could be expanded.) I just googled for <<Hessel de Vries Libby>> and found hundreds of pages in English that discuss this. So perhaps some of them could be used to replace the Engels reference. —Daphne A 10:42, 13 June 2006 (UTC)

German reference

They were included after a request to incorporate material from the German Wikipedia article, while the English article was tagged as lacking adequate references. Jclerman 09:10, 13 June 2006 (UTC)

I looked at the two German references, and I do not see that they would belong here even if they were in English. Rather, they belong in articles listed in the Examples section.

They discuss examples of dating which are frequently discussed in this page and in others related to radiometric dating. Jclerman 10:39, 13 June 2006 (UTC)

You have not rebutted my point. Daphne A 10:54, 13 June 2006 (UTC)

And they are in a language that is not good for en.wikipedia.org.

Not good is your subjective opinion. Others differ, particularly those with experience in radiocarbon dating. Jclerman 10:39, 13 June 2006 (UTC)

Wikipedia articles are supposed to be for the general reader (this is policy). A tiny minority of others do differ; so what? You appear to be debating for its own sake. Daphne A 10:54, 13 June 2006 (UTC)

I do not know other references to include. Perhaps Radiocarbon After Four Decades (1992)? Other than that, I suspect there is just papers in peer-reviewed journals.

Suspicions and assumptions are not enough ;-) Jclerman 10:39, 13 June 2006 (UTC)

What is the purpase of this comment? Daphne A 10:54, 13 June 2006 (UTC)

• You said you suspected there were only peer reviewed papers left. And you had assumed that it would take me only minutes to comment on your changes. Etc. Jclerman 11:27, 13 June 2006 (UTC)

—Daphne A 10:13, 13 June 2006 (UTC)

The reference you quote is the Proceedings of the Radiocarbon Dating Conference of 1990. You could make a section in which to list all the conferences, including the Nobel Symposium volume. Jclerman 10:39, 13 June 2006 (UTC)

The volume I cited contains review papers, unlike most conference proceedings. The Nobel volume is interesting only for history-of-science purposes. You said that you wanted to include more references; I am entirely happy with that. Do you have constructive suggestions for useful things to read to learn more about 14C dating?

Not the Nobel Volume, but the Nobel Symposium on Radiocarbon Dating. Begin there. It's not history of science. Jclerman 11:27, 13 June 2006 (UTC)

Do you mean the one from 1960.

If not, then there is nothing to talk about. Daphne A 10:54, 13 June 2006 (UTC)

• Have you restored the Engels reference yet?

Jclerman 11:27, 13 June 2006 (UTC)

I did not agree to restoring it, and will now delete it, as indicated in above discussion. Daphne A 18:22, 13 June 2006 (UTC)

The reference to Engels is now deleted. If you explain what the Dutch-language reference says (in clear English) though, then we can find English-language links that say the same thing—and cite them. Daphne A 18:48, 13 June 2006 (UTC)

Links to calibration curves

Several links to calibration curves articles are missing. They are of crucial importance for understanding radiocarbon dating. You can find plenty of discussion about this topic. Jclerman 10:04, 13 June 2006 (UTC)

Also, the broken link is now: http://c14.arch.ox.ac.uk/calibration.php

Jclerman 10:10, 13 June 2006 (UTC)

I've put the fixed broken link back in.

I do not know which other links you mean are missing. Some links were moved to other sections ("See other" and "External links") or appeared to be wholly redundant. Will you explain?

—Daphne A 10:36, 13 June 2006 (UTC)

Again, redundant is in your IMHO. Not in those who rather than read the article, use it as a tool and go to the references and the external links when they want to calibrate a date. Jclerman 10:48, 13 June 2006 (UTC)

You said "several links". I only know of one: CalPal-online.de. This is not a program used by many people (for good reason); moreover, if readers want it, they can easily get it by following either the CalPal link (which is still there) or the radiocarbon.org link (which has the advantage of leading them to more widely-used programs). Having two links to CalPal looked almost like advertising. —Daphne A 11:01, 13 June 2006 (UTC)

No advertising now. It is only once. And where I and other that use it several times per day can find it. Jclerman 11:14, 13 June 2006 (UTC)

You have included the link twice—in direct contradiction of your claim—and, worse, you have made CalPal (a program that is little used for good reason) the canonical link for calibration. You appear to be playing a game that is inappropriate for Wikipedia. I ask you to cease such actions. Daphne A 18:32, 13 June 2006 (UTC)

I see now that you actually included three links to CalPal. Daphne A 18:44, 13 June 2006 (UTC)

NOSAM thanks

Thanks for the correction. I expanded the acronym to avoid further confusion between oceanic agencies. Jclerman 11:07, 13 June 2006 (UTC)

Some idiot told me:

"I will now point out the largest flaw of carbon dating, it assumes the rate of decrease in carbon on earth has ALWAYS been constant, which is absolute bogus. Carbon dating can only be trusted for smaller dates, such as a few thousand years, because it is mroe logical to assume that less "stuff" has hapenned in the last 2 thousand years or so."

Is he an idiot?--Greasysteve13 15:03, 23 June 2006 (UTC)

I believe the question you intended to ask is "Is he correct?" Whether or not your friend is an idiot is of no interest to this encyclopedia. First, ask yourself: why would it be logical to assume that "less has happened" in the last 2 000 years and what would this have to do with radiocarbon dating? Then, read the section "calibration" of this article and ask yourself: do scientists assume a constant level of C14 for absolute (non-approximate) dating? Hope that helps. jdbartlett 16:46, 23 June 2006 (UTC)

Thankyou--Greasysteve13 04:13, 24 June 2006 (UTC)

Simplified archaeological sample age determination for laymen

New section deleted because:

• The heading was confusing. Radiocarbon is used to date much more than archaeological samples, as said in the articles related to C-14. The reader would get the impression that the simplified method works only for archaeological samples.

The simplified calculations proposed have a granularity of one half-life, i.e. 5730 yrs. This gives the reader a false impression re the real precision of the method when seeing dates quoted with a +/- statistical error of, e.g., 100 yrs. BTW, such coarse method is described in the article about radiometric dating, see [4] Jclerman 01:38, 26 June 2006 (UTC)

I have written another trial version of the 'simplified calculation bit with perhaps a bit more explanation/derivation, see User:Vsmith/Dating calc - comments? The method gives the same dates (w/in about 0.1 yr) as the standard formulae that seems to intimidate some readers in the section Computations of ages and dates of this article. Vsmith 15:30, 26 June 2006 (UTC)

I looked at the method on your user page, but it seems like verbiage. Also, the formula is not that important, because you really have to calibrate the ages (via tree rings). You are probably right that the formula unnecesarily intimidates people though. Perhaps the discussion of the formula should be improved. Also, I like the example that you give at the end on your user page: 2 half lives * 5730 yrs/half life = 11460 yrs; this is easy to understand and should help people who have trouble with the formula.

—Daphne A 16:23, 26 June 2006 (UTC)

I also looked at Vsmith's proposal. I tried to shorten it but, in fact, I got it longer. I made some punctuation and other minor changes that migth be incorrect or unwanted... (It's at User:jclerman/Dating calc.) True, we do dendro calibration, but we need a raw date to input into the calibration curves, and the readers might want to know how do we get the number/date we input. Perhaps the table could have an extra row with the corresponding dates for each fraction, thus avoiding the mystery of the logs... Jclerman 23:27, 27 June 2006 (UTC)

Looks good. This is the way I introduce the concept to my beginning high school Chem 1 students as they haven't been exposed to rate laws and such and this is easier for them to grasp. I use base 10 logs for them as it's easier for them to grasp (most don't know what logs are) and with a brief intro they can use another button on their calculators :-). The example giving non-integer half lives is important as it is simply the most common real world outcome (I just picked a random fraction off the top of my head there). Probably should convert the table to a wiki table from the HTML one I made if it is a go. Cheers, Vsmith 02:01, 28 June 2006 (UTC)

Okay—my suggestion is that the new text replace, rather than supplement, the current explanation, except keeping the first sentence of the current explanation.

You said that "we need a raw date to input into the calibration curves". We need the raw 14C measurement, true, but we do not need to do the exponential calcuation. Rather, the raw 14C measurement can be directly compared with the raw 14C ages in tree rings (it is actually easier this way, because then the distributions are true Gaussian).

—Daphne A 04:19, 28 June 2006 (UTC)

Thanks to Vsmith and Daphne A for your useful comments. I'll be considering them when I make some minor edits to the sections in discussion. It will be later, probably overnight. Thanks again. Jclerman 17:41, 28 June 2006 (UTC)

My suggested Note, still rough, in progress, etc. is ready to be viewed at User:Jclerman/Dating calc.--Jclerman 16:18, 29 June 2006 (UTC)

Attn Vsmith: I wonder if you could put a webcam in your classroom. We would not only learn something, but we would avoid convoluted discussions ;-). I destroyed a little more your table, examples and text. See suggestions that I included between [] (I am not familiar with table editing, neither wiki or html). See also my comments below. And your non-integer n is a great idea. See my suggestion for an extra example with a larger n. --Jclerman 16:18, 29 June 2006 (UTC)

OK, I converted the table to wiki format with an online tool ([5] wow was that easy) and added the age (year) row. Also added one more column - just cause it would fit :-) Note, I removed the cell borders as it gives a "cleaner" look, but can set it back to one if preferred. The only problem I find with using the "easy" method is that my advanced chem students want to use it rather than the "book" rate constant eqn. - hey they learn :-) I try to have them also work with fractional values of n also, even had my adv students calculate how many C-14 atoms decay per second in an average human, one second is a very small fraction of 5730 years. Interesting result 'tho I can't say how accurate. Cheers, Vsmith 02:57, 30 June 2006 (UTC)

Attn Daphne A: I failed to understand your statement: We need the raw 14C measurement, true, but we do not need to do the exponential calcuation. Rather, the raw 14C measurement can be directly compared with the raw 14C ages in tree rings (it is actually easier this way, because then the distributions are true Gaussian). Can you please explain this method and give a reference to it?. Since to use calibration curves one needs to input a raw age or raw date value, I've expanded my current draft in progress to explain the experimental procedures to obtain such value before using a calibration curve. One of my problems was not to understand what do you mean by raw 14C measurement (activity?, age?). Other statement I couldn't parse is: the raw 14C ages in tree rings. How different is this from a calibration curve? I'll be glad to delete/edit/merge relevant statements in the article's Note as soon as I understand your method without the exponential. --Jclerman 16:18, 29 June 2006 (UTC)

To me, the proposed new text looks too complicated. Many people will not understand it; among those people that do, they could find out what they need from the article on Exponential decay (which is linked to from this article). I preferred your previous proposed text!—as a replacemnt for the current text.

As for the term "raw", I'd used this because that is what you had used. In any case, one problem with reporting radiocarbon ages is that they are not true Gaussian (for example, 15000±50 is usually considered to be Gaussian, but in fact it is log-Gaussian). As for tree rings, suppose that their (¹³C-normalized) activity levels are measured to be m1±s1,m2±s2,m3±s3,...,mk±sk; and suppose that we have a sample whose activity level is m0±s0; then it is clear that we can interpolate the tree-ring activity levels and calibrate the sample measurement directly against the interpolated curve. So we do not need to use exponentials.

—Daphne A 09:42, 1 July 2006 (UTC)

• I don't think I've used the expression "raw C14 measurement" unless I was quoting you. Notice that I would not know what it means. I use "raw C14 date", "raw C14 age", "calibrated (calendrical) C14 date", "raw C14 (radio)activity", "net C14 (radio)activity", etc. Notice that only the "raw activity" is the result of a primary measurement. All other quantities are calculated.

The first time that the word "raw" was used was in your posting at 23:27 on June 27. I actually don't know what "raw" means in any context. Anyway, though, I think we might be better off letting this subject drop, and I will agree not to use "raw" anymore. —Daphne A 13:24, 8 July 2006 (UTC)

• The "Note section" in the article and its current draft proposal are not intended to be a main section of the article. In fact, they grew up during six months of extensive exchanges with users from varied backgrounds. It still keeps growing in length due to the need to define the quantities we are using. Once we agree about what we all mean, it could be trimmed down.
• I still do not understand how can you avoid the exponential to obtain a "calibrated (calendrical) date" from a "raw C14 age". To understand what you mean I need to know what is that you measure. what dendrochronological information you use, the physical measurements you perform and the ensuing data processing.

Okay, here's a simplified example. Measure the (¹³C-normalized) activity levels of tree rings from the years AD 500, 510, 520, 530, ..., 800. Also measure the (¹³C-normalized) activity level of the sample that you want to radiocarbon-date. Suppose that the sample has the same activity level as the tree rings from AD 700 (and a different activity level than all other measured tree rings). Then the sample must be from about AD 700. And if the sample has an activity level between the activity levels of rings from AD 700 and AD 710, then the sample is from sometime between those two dates. (There are details that I've left out here, but I hope the example illustrates the main idea okay.) —Daphne A 13:24, 8 July 2006 (UTC)

• You might be referring to a new or unsourced method, which even if it could not be incorporated in the article (by Wikipedia policies) it would be valuable to explain within this discussion space for the benefit of radiocarbon researchers.

--Jclerman 19:06, 5 July 2006 (UTC)

This is the method that seems to be described—albeit briefly in the last paragraph—at http://www.informath.org/Basic14C.pdf (one of the External links for this article). There should be better sources. —Daphne A 13:24, 8 July 2006 (UTC)

To me it seems to be a simplification for teaching purposes, like the use of isotope abundances (in parts per trillion) rather than measurements on basis of the percent modern, as it is done. I am describing how it is done in the following. I fail to see the advantage in reconverting data from ages to activities, though. See below: --Jclerman 01:36, 11 July 2006 (UTC)

I agree that it seems to be for teaching purposes, rather than explaining how calibration programs actually work. Which is better for Wikipedia? (This is a serious question; I'm not really sure.)

Regarding what you wrote below, it mostly reads nice and clearly! The explanation for 13C could be clearer, I think. Also, the text does not account for AMS labs, which can use milligram amounts of carbon. And it is untrue that trees are from many latitudes: there is little equatorial, for example.

—Daphne A 11:46, 14 July 2006 (UTC)

Each simplification done for the sake of teaching later requires longer add-ons. It would be senseless to sample Equatorial treerings because most if not all species grown in such latitudes do not have annual rings since there are no marked seasonal variations and, anyhow, because the Equatorial masses of air are a mixture of Northern and Southern Hemisphere air. The article states clearly that corrections or normalizations for isotope fractionation have not been included (yet?). Where is the limit between an article and a how-to manual? Decontamination of samples for extraneous carbon has not been described either. My below discussion of calibration clearly refers to (radio)activity (detection)counting, thus AMS was not mentioned. Anyhow, when the collection of samples with potential dendrochronological+radiocarbon value was made, AMS had not yet been foreseen. --Jclerman 12:18, 14 July 2006 (UTC)

Yes, equatorial trees do not have annual rings—that was my point: it indicates that the proposed statement about "diverse latitudes" is misleading. Activity levels are determined by AMS. The paragraph about "grams of wood" seems to be irrelevant here and potentially misleading. Also, the part about "protected species" is new to me; are you refering to bristlecone pine? —Daphne A 07:00, 18 July 2006 (UTC)

1. "Diverse latitudes" is not misleading. Have you seen the list of the different localities, continents, elevations, in N and S Hemispheres from where tree sections were collected?

2. AMS is mass spectrometry, it does not measure activities. It counts atoms which have not yet disintegrated: it measures in units of "number of [undecayed] atoms" which are collected in a "cage" or "cup" whereto they are deflected. The earlier method of (radio)activity counting detects only the atoms at the moment they are disintegrating: thus it measures in units of "dpm" as registered in a "counter" (proportional or scintillation).

3. "Grams of wood" is neither irrelevant nor misleading. Lets the reader infer the non-trivial task of chiseling wood from a tree section to obtain suitable amounts of wood that were used for "points" on the calibration curves.

4. "Protected species" lets the reader infer that "tree rings don't grow on [free and easily available] trees". FYI, bristlecone pine is not the only such species used for calibration because it grows in very restricted localities. Calibration of the radiocarbon scale had to rely also on S Hemisphere and European trees.

--Jclerman 07:44, 18 July 2006 (UTC)

A non-specialist might well tend to think that "diverse latitudes" includes non-temperate latitudes. Activity levels can be determined from AMS measurements (think about it). What does it matter if conventional radiocarbon was used for most of the calibration measurements?—and I think that AMS was used for a few of the measurements that went into INTCAL04 (though I'm not certain). It is potentially misleading because without more discussion readers might think that grams are always necessary. Many of the trees used for calibration are readily-available oaks; I don't think that they are protected. The problem with the oaks was not that they were/are protected, but rather that they had died a long time ago and had to be retrieved from bogs, etc.

Maybe the root of our apparent disagreement is over how much detail should go into this article. My view is that too many details obscure the central points and leave readers more confused than enlightened. Possibly a compromise would be to include many more details even than you are suggesting, and put that in a separate article?—just an idea.

—Daphne A 09:31, 18 July 2006 (UTC)

About calibration

• Radiocarbon dating analyses are destructive. This means that the wood of treering samples is combusted to produce carbon compounds (carbon dioxide, benzene, etc) whose [specific raw (uncorrected, unnormalized) radio]activity can be detected by counting its disintegrations per minute.
• To attain the appropriate precision and accuracy, the determination of such raw activity requires grams of wood and weeks of counting its radioactive disintegrations.
• The computation of the net specific activity of each sample requires extra weeks analyzing background ("dead" radiocarbon) and modern ("AD1950") standard samples, then to be normalized to a standard C13 value.
• The raw radiocarbon ages are evaluated from the standardized specific net activities described above.
• The series of treerings to be dendrochronologically & radiocarbon dated to be used to calibrate the radiocarbon dating scale were the result of decades of explorations begun in the early 1960s. Remote sites were explored at diverse latitudes and elevations, searching for unique rare, living and dead millennary trees to obtain suitable samples. They were mostly from protected species.
• All the determinations of the radiocarbon activities described above have been cross-correlated and preserved as calibration curves (or tables). By definition a calibration curve has quantities of the same kind on both axis, namely calibrated dates (given as Calendar Years) on the horizontal axis and raw ages (given as Before Present years) on the vertical axis. See Example 1.
• Should a conversion curve be preferred, rather than a calibration curve, the ages on the vertical axis can be converted to the original radiocarbon activities by a simple mathematical operation.
• Any radiocarbon activity from a sample to be dated might match the radiocarbon activities of more than a single tree ring. In Example 1, the sample whose activity dated as 900BP old matches 5 different calendar dates which were obtained from 5 different dendrochronologically dated treerings.

File:C14dendro.jpg

Example 1.

• In practice, things are complicated by the statistical uncertainties (a) of the curve itself, which is really a band, (b) the uncertainty distribution of the sample's activity, and (c) the non-monotonic character of the calibration band. Graphical examples covering the statistical uncertainties and their propagation are given here [6] and here [7].

--Jclerman 01:39, 11 July 2006 (UTC)

---

Straw poll

This straw poll is being conducted to determine which of the following points of view are favored by users so as to reach a neutral point of view.

1. In a sealed container where Carbon-14 is not replenished "Carbon-14 is never completely gone. It decays exponentially ad infinitum."
2. All Carbon-14 in a sealed container without benifit of replenishment will eventually decay into Nitrogen-14 as the result of Beta decay.

Please sign your name using four tildes (~~~~) under the position you support, preferably adding a brief comment. Since these are opposing points of view please do not sign your name to more than one.

Those who favor the "eventually gone" point of view (POV number two)

1. I favor the expression of the second point of view as being neutral for the following reason:
   • Since atoms are indivisible then the number of parent isotopes atoms remaining when the variable P in the age equation $t={\frac {1}{\lambda }}{\times }{\ln \left(1+{\frac {D}{P}}\right)}$ is less than one will be zero. ...IMHO (Talk) 22:47, 5 July 2006 (UTC)
2. I did a quick estimate and found that, according to the formula, 1 mol would decay to less than one atom in about half a million years: well within the lifetime of the universe (or even the canister). There is nothing wrong with admitting that the formula is just a statistical prediction of the decay, not an exact infinite curve. −Woodstone 15:37, 6 July 2006 (UTC)

Those who recognize the irrelevancy of this straw poll

1. Irrelevant due to being based on a complete misunderstanding and attempted mis-representation of the issue by User:Pce3@ij.net. - Vsmith 00:39, 6 July 2006 (UTC)

   • This is the only issue as far as I am concerned. However, please be mindful of the fact that if you think this issue is irrelevant then this is your opportunity to state exactly why you think that way instead of trying to dodge the issue by just making the claim that you think this issue is irrelevant. ...IMHO (Talk) 00:53, 6 July 2006 (UTC)

2. This OR has been dscussed extensively, receiving negative comments in many forums. Regretfully, User:Pce3@ij.net does not accept that "others" might be correct in their assessments of his, admitedly, very creative approaches, e.g., the one that he published as an unreviewed Wikibook. The topics that originated the current "poll" can best be followed on a trail threaded along the wikipedia help desks, policy boards, and the dicussion/talk pages of many related articles. They can be located by surfing the contribs list of User:Pce3@ij.net (who also signs as IMHO) during the recent several weeks. Such trail shows extensive and obfuscating discussions about dating formulas, being rebutted by a host of users: (a) because he ignores concepts such as asymptotes, exponentials, and division by 0, and (b) because he does not understand the fact that nature's behavior can not be dictated by formulas. True, physical phenomena can be approximated by mathematical expressions; however, the reverse is not true: mathematical expressions can not and do not dictate to the physical world how it is to behave. --Jclerman 02:07, 6 July 2006 (UTC)
3. Pointless timesink that ought to be abandoned. It seems transparently clear to me that deliberately inflammatory interpretations of that "nice try" thing are being taken.
   Yes, we all agree that atoms decay as units. Yes, we all agree that all units of X could decay. However, we can also say that, under all practical circumstances, complete decay doesn't occur, and we should be able to accept that generalization. Similarly, nobody complains when a falling-body calculation ignores the attractive force that a bowling ball exerts on the Earth, even though it's physically real. — Lomn | Talk 04:00, 6 July 2006 (UTC)
4. What Vsmith said. Melchoir 04:26, 6 July 2006 (UTC)
5. Whoever wanted this straw poll does not understand how science is supposed to work. Science is not supposed to be a democracy, and issues are not decided by vote. With that said, here is an example.
   Suppose that we could take the entire atmosphere and put it in a perfectly-sealed container for a million years. The atmosphere has a mass of about 5*10^21 g of which about 0.053% is CO₂ [1]. Thus the atmosphere contains about 6*10^16 mol C, and so roughly 4*10^28 atoms of ¹⁴C. Consider any one of those atoms: after 5730 years, the probability that it has not decayed is 0.5; so after a million years, the probability that it has not decayed is about 3*10^(-53). The probabilities for the different atoms decaying are independent. Thus the probability that even one atom of ¹⁴C is left in the container after a million years is about 10^(-24). I.e. effectively zero. —Daphne A 13:40, 8 July 2006 (UTC)

• This straw poll has nothing to do with deciding an issue in science. This straw poll is for the purpose of determining how best to synchronize the results of a model of the age equation with scientific reality by those who are apparently old school and learned the age equation prior to the development of personal computers which have allowed students and laymen to do extensive modeling and analysis that has taken them well beyond old school. ...IMHO (Talk) 14:32, 8 July 2006 (UTC)

Summary statement

1. Since the development of personal computers and sophisticated software packages such as Excel spreadsheet the ability of the student or laymen to model equations has become commonplace and routine. Therefore it has become necessary to clarify the results of such modeling when applied to the age equations… ...IMHO (Talk) 10:56, 8 July 2006 (UTC)
2. The following facts are known and have been established: Atoms of Carbon-14 decay as units and all units of Carbon-14 can decay completely.Lomn It is calculated that a mole of Carbon-14 atoms would decay to less than one atom within about a half million years. The age equation represents a statistical prediction of the rate of decay rather than an infinite curve.Woodstone Suppose that we could take the entire atmosphere and put it in a perfectly-sealed container for a million years. The atmosphere has a mass of about 5*10^21 g of which about 0.053% is CO2 Density and Mass. Thus the atmosphere contains about 6*10^16 mol C, and so roughly 4*10^28 atoms of 14C. Consider any one of those atoms: after 5730 years, the probability that it has not decayed is 0.5; so after a million years, the probability that it has not decayed is about 3*10^(-53). The probabilities for the different atoms decaying are independent. Thus the probability that even one atom of 14C is left in the container after a million years is about 10^(-24), i.e. effectively zero.Daphne A. ...IMHO (Talk) 11:40, 9 July 2006 (UTC)

...IMHO (Talk) 00:55, 6 July 2006 (UTC)

May I suggest closing and archiving this section?--Jclerman 17:55, 7 July 2006 (UTC)

• This straw poll is for the purpose of providing a summary statement for the benefit of readers who may be confused when modeling the age equation and not the place for you to reiterate your inability to comprehend the problem from a lay or student point of view. Hiding information from students will not solve the problem but only make them question why the problem has not been addressed in the past only to learn that it was hidden away as if that would make it forever go away. Please give others who are confronted by this question the right and the opportunity to review previous coverage. Thanks. ...IMHO (Talk) 01:00, 8 July 2006 (UTC)

I would now like to thank everyone for their participation in this straw poll and ask that each of you post a statement beneath the "Summary statement" subsection above that will in their opinon best summarize and integrate the results of this straw poll into the article text proper for the benefit of readers by July 10, 2006 at 21:00 EST or July 11, 2006 at 00:00 UTC. Thanks again to everyone for your participation. The experience has been great! ...IMHO (Talk) 19:35, 7 July 2006 (UTC)

• This year the class was granted a choice between donating the money they earned along with the sponsorships they received to the Wikimedia Foundation or to pay for a field trip to a nuclear facility where they could talk with nuclear scientist and engineers. Rather than waiting until the last day of the straw poll the class unanimously voted to spend 100% of its funds on the field trip. Thank you for helping our students reach their decision and good luck next year. ...IMHO (Talk) 18:34, 9 July 2006 (UTC)

External Link Debate

Apparently someone thinks that a link to an article about possibly the biggest mistake in radiocarbon dating history is spam or an advertisement. Read the article. It is a non-commercial article about how radiocarbon dating mistakes happen. It does not promote me, my friends, my company or my company's products. The page in the external link does not link to any pages about me, my friends, my company or my company's products. There is no advertising on the page. The is just an article. It does not question the scientific accuracy of radiocarbon dating. It illustrates how serious mistakes can be made in the sampling procedures.

It is not my intent to spam anything. My sole intent is to link to a page that illustrates problems that can occur. That certainly seems better than 1) filling up this page in Wikipedia with material that detracts from the article (which is excellent) or 2) ignoring the fact altogether.

Dan Porter Innoval 14:39, 25 August 2006 (UTC)

Regarding your recent changes to Radiocarbon dating, the link that you are putting in is included in the article Shroud of Turin. The article on radiocarbon dating includes a link to that article in the Examples section. —Daphne A 14:43, 25 August 2006 (UTC)

Daphne, thanks for responding. I'm not going to persist. It isn't that important to me. But the issue of radiocarbon dating issue, mistakes, controversy, etc. is real. The public is all to easily convinced that such testing is bulletproof and the radiocarbon article does not address that. Material intrusion (which is not the same as contamination) is one such issue. Peat bogs, water soaking, and the shroud are examples. Perhaps and article is needed on material intrusion or more generally problems. My fear is opening up the door for the emotional/religious issue raised by creationist-Christians and conspiracy theory buffs.

Under examples in the current page it might be useful to point out, there, that some of these results are controversial (which is actually better NPOV than leaving a false impression in the minds of many who do not always follow links. Radiocarbon dating is good science but inept use of the process sadly happens.

Having said all that, I nonetheless, recommend the external link remain. It is useful and illustrative.

Dan Porter Innoval 15:14, 25 August 2006 (UTC)

Dan, I think that your point about the article not addressing how non-bulletproof radiocarbon dating is is excellent. It would be really good to add a new section on that to the article, which could talk about the Shroud, bogs, etc. As for creationists, etc., they might well show up—but lots of other folks will be watching and will revert their changes.

If you wanted to write such a section, feel free (of course). Even something short to get things going would be nice, as long as it is well referenced. There are also location dependencies worth discussing: Jclerman asked about this above [07:51, 18 July 2006], and I cited a paper by McCormac et al. in reply; other work in this area is by Kromer et al. [Science, 2001], Keenan [AWE, 2004], and Dellinger et al. [Radiocarbon, 2004].  —Daphne A 16:22, 25 August 2006 (UTC)

No controversy section?

I think we need a controversy section for this article. There have been many questions regarding the accuracy of Radiocarbon dating, and none of it is found in the article. A reader might assume that it is beyond-question. --andrew leahey 06:05, 25 October 2006 (UTC)

Write it up and put it in. Everyone will fix it. (SEWilco 18:09, 27 October 2006 (UTC))

Deja vu. That section and an article existed some time ago and were deleted by consensus. Read all of the above discussions. If you have new evidence, cite the sources for the section you added. Meanwhile it has been deleted. As stated above: Even something short to get things going would be nice, as long as it is well referenced and relevant.

Jclerman 05:52, 28 October 2006 (UTC)

Perhaps a starting point would be to summarize here in the Talk page what the controversial points are which have already been discussed here in Talk. Those points which haven't been disproven are of particular interest, although some issues and counterissues are probably still unresolved. The immediately preceding section refers to the shroud of Turin, where apparently a sample happened to be of a recent repair and thus the carbon date was relevant to the repair rather than to most of the shroud; this would be a case of a sampling error rather than a radiocarbon issue. (SEWilco 21:32, 30 October 2006 (UTC))

Feel free to summarize de novo all the points discussed in the past, and post a concise list including the rebbutals. Then we can see what's left to explain. Jclerman 23:12, 30 October 2006 (UTC)

To be honest, if what I posted wasn't "relevant", I'm wondering what would be. --andrew leahey 21:14, 30 October 2006 (UTC)

Your statements were:

"There have been numerous criticisms of radiocarbon dating, and questions involving its accuracy. Most criticisms stem from questions involving the rate of decay of carbon-14. Critics contend that there is no way to be sure it decays at a consistant rate, and therefore no way to be certain radiocarbon dating is consistantly accurate. Experiments performed using the isotopes of uranium-238 and iron-57, have shown that rates can in fact vary."

The questions about accuracy can be said about most measurements in chemistry and physics. Without a reference, they don't pertain to any article. Who said that the rate of decay of carbon-14 is a point of contention? Without a reference it cannot be either agreed upon or contested. Also, the accuracy of radiocarbon dates and their calibration have been extensively documented. If you know of anything new, cite it. How do the U-238 and Fe-57 decay rates vary (source?) and how would it be relevant to C-14 (it might be or not, but you can't just make blanket statements in an article about a scientific topic). Please, review the references cited and the past discussions.

Jclerman 23:12, 30 October 2006 (UTC)

Controversy Section

I have created a controvery section based on some independent research I'd stumbled upon. Keep in mind that I'm an English teacher and bridge writer, not a scientist. I also don't know the right form for Wikipedia pages, so I need it wikified at the very least. It's also a trial balloon to see how this topic will be handled by the community as a lot of people have express pretty extreme distolerance for non-traditional points of view. Controvery does exist in scientific circles.Eljamin 17:14, 14 December 2006 (UTC)

Thanks for the opportunity to comment on your paragraph. I suggest you consider reviewing it before deciding if a new version is warranted. Meanwhile I've deleted it from the article and made some rough edits and comments here below. They are not complete as unfortunately I don't have the time and the health to do an in-depth analysis of your text. Others will do it, surely. Meanwhile you should read all the past discussions about this article. They cover more topics than those you chose, but they might be useful. See also below my intrusions and mangling of your text (to see your untouched original text, go to the relevant version of the article):

Despite being accepted by most scientists, Radiocarbon dating is a controversial subject, mostly because readers confuse dates of samples contaminated by modern materials. One of the reasons for this controvery is the existence of ¹⁴C in places where it should not exist. For example, many coal deposits have been found to contain carbon-14, which makes sense if there has been contamination by modern materials like bacteria growth or by in situ formation of carbon-14. Such extraneous carbon does not influence much the dates of carbonaceous samples up to some 100 kyr. The reader should calculate it rather than accept gross descriptions of an alleged controversy. For example, statements like "the age of the deposit is 300 million years old. The easy answer is the assumption that the coal deposit must therefore be less than 60,000 years old since there are still detectable amounts of carbon-14" show that an appropriate calculaion of the age has not been pursued and that the detectability limit could have been misunderstood. According to Dr. Harry Gove, as re-told by somebody else in http://www.talkorigins.org/faqs/c14.html. fossil fuels vary widely in carbon-14 content, usually correlated with the radioactivity in the rocks around them. In this case Gove wants a material to be used in neutrino detectors, and his results bear little relevance to radiocarbon dating as can be inferred from a knowledge of the technology and of David Lowe's 1989 paper on the Radiocarbon journal where he made a case for carbon-14 resulting from fungus and bacteria contamination. Since Lowe's paper [8], there have been many more reports of deep subterranean bacteria, which apparently form a heretofore unrecognized ecosystem deep below the earth in rocks and in oils, which will need to be taken into account when decontaminating such materials before using them as reference background for radiocarbon dating of carbonaceous samples up to 60 to 120 Kyrs. Nothing implies that this would be one or more new carbon-14 dating methods. It has been repeatedly shown that carerully decontaminated materials give radiocarbon dates which are comparable with historical dates and with other dating methods.

Jclerman 18:30, 14 December 2006 (UTC)

It appears that the level of 'contamination' of coal is ~0.2% which amounts to ~30-40kyears. This appears to contradict the "up to some 100 kyr" idea. Dan Watts 18:53, 15 December 2006 (UTC)

About the apparent contradiction, the "some 100 Kyr" refers to the later "60 to 120 Kyr" which refers to the statement "Dr. Gove and his colleagues are currently trying to improve AMS technology to be able to identify certain fossil fuels that have extremely low 14C content. Current AMS techniques have a 14C/C detection limit of about 10-15 (corresponding to 60,000 yrs), and Dr. Gove's current research, this year, is aimed at improving detectability to 10-18 (110,000 yrs)" as quoted from Kathleen Hunt cited by Eljamin [9]. Then, Lowe says "Initial results indicate that geologically formed graphites contain little {sup 14}C and are likely to be good background test materials, especially in {sup 14}C AMS laboratories." [10]. Jclerman 21:20, 15 December 2006 (UTC)

How about the AMS results on diamond with measurable ¹⁴C? (See [11] for a discussion.) Is diamond supposed to be more succeptible than graphite to 'contamination'? Dan Watts 21:52, 5 January 2007 (UTC)

It has been replied in [12] ("... about radiocarbon in diamonds proving that the diamonds are only thousands of years old, you can remind them that they're just measuring noise in an atomic mass spectrometer!") Jclerman 00:25, 6 January 2007 (UTC)

You, of course, may say anything you wish. The abstract (see [13]) says that they have measurable ¹⁴C levels and implies that sample processing and instrument limitations are the cause. To use Occam's razor, which is simpler?

1) Every sample and every AMS instrument is contaminated (by currently unknown means)/intrinsic/imprecise at the 0.2 percent modern carbon level ( 100X the AMS limit of ~ 0.002 pmc) See Bird et. al. Radiocarbon Dating of “Old” Charcoal Using a Wet Oxidation, Stepped-Combustion Procedure, Radiocarbon, 41:2(1999), pp. 127-140.

2) The stuff just isn't that old.

Your choice. Dan Watts 03:43, 6 January 2007 (UTC)

That's very interesting. A controvery section which explicitly states that there is no controvery. I also note the use of the phrase: The reader should calculate it rather than accept gross descriptions of an alleged controversy which I believe must SURELY violate the Wikipedia manual of style, as highlighting the word and using the word "alleged" must surely raise POV/NPOV issues. The crux of the controvery revolves around the age of the earth. The pro-evolution crowd says, the earth is at least a billion years old, during which time carbon-14 was being constantly created and destroyed at various rates, after which it reached an equilibrium state (which changes, of course, based on solar radiation, amount of carbon-12, etc.), which accounts for all the fudge factors in the carbon-14 dating method. The young earth group thinks, well, the earth is relatively young and since it takes 30,000 years for carbon-14 to reach an equilibrium state, we can't just go and assume that it is in equilibrium... which is drowned out by shrill laughter, ridicule, accusations of being a religious fanatic, etc. Wouldn't it be better to perhaps try to build a more solid refutation, perhaps as was done here: (http://www.talkorigins.org/faqs/faq-age-of-earth.html) ? Although not a complete refutation of all the arguments advanced for a young earth, at least the writer has done his homework. Come to think of it, perhaps some of that can and should be included in the age of the earth page. I am not given to rash action, but if this is the general way in which alternative opinions are addressed then surely this page needs a NPOV/POV disputed tag added, don't you think? Eljamin 17:03, 15 December 2006 (UTC)

Controversy - take 2

Removed the following:

Not everyone accepts the idea that the half-lives of radioactive isotopes are constant. Many Young Earth Websites claim that the half-life of carbon-14 can be changed by the presence of magnetic fields and may be variable over time. Since the discovery of radioactivity was relatively recent compared to the half-lives of radioactive isotopes it may be too soon to know one way or another. Although most physicists scoff at the idea that magnetism could affect nuclear processes, there are theories that postulate interactions between the elemental forces. One of the most popular theories is called "Heim-Dröscher space" in which a German physicist named Burkhard Heim attempted to reconcile Einstein's General Theory of Relativity with Quantum Physics. Although the theory remains unproven, there is evidence that his theory is correct because it can be used to calculate the exact masses of fundamental particles, which calculations have been substantiated by measurements. Unfortunately the majority of physicists have never heard of Heim's theory, and most of those contacted said that "they couldn't make sense of Dröscher and Häuser's description of the theory behind their proposed experiment."

It was supposedly supported by http://www.newscientist.com/channel/fundamentals/mg18925331.200-take-a-leap-into-hyperspace.html - but I find nothing there to support a controversy here. Vsmith 17:15, 4 January 2007 (UTC)