CARBON 14 DATING AND RELATED MATTERS

This page is provided to discuss aspects of the Carbon 14 date of the Shroud of Turin and related matters which bear on the likely accuracy of the 1988 C14 date. See Books on Carbon 14 Data for more information.
BMScientistsShroudAFake.jpg
British scientists Professor Edward Hall, Dr. Michael Tite, and Dr. Robert Hedges announcing the results of the carbon dating of the Shroud of Turin at a press conference held at the British Museum on October 13, 1988.

The Carbon Dating of 1988

The Carbon 14 dating of 1988 found that the linen of the shroud had ceased to absorb C-14 between 1260 A.D. and 1390 A.D. While there were some statistical anomalies in the Carbon 14 data (a variety of papers are available on www.shroud.com) there is no serious reason to doubt the result produced by the Carbon 14 testing laboratories. However, the paper written by Ray Rogers (see below) established that the C-14 sample area was contaminated by cotton and that the sample gave a positive test for vanillin which shows that the material was much younger relative to the rest of the shroud which does not test positive for vanillin.

How the Carbon Dating Went Wrong

The protocol agreed upon for the carbon dating was arrived at in late September and early October in 1986 in Turin. William Meacham was a participant and gives this account:
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The first serious error in planning for the C-14 dating was made by STURP. In contrast to the other excellent science that this group did on the Shroud, their approach to C-14 was poor. They proceeded to draw up a plan for the testing without having anyone in the group who had ever done C-14 dating in a professional context. Another serious error made by STURP was not to include a textile conservator in the group. When a major rift occurred with the directors of the C-14 labs, STURP's lack of knowledge of the normal dating procedures and their lack of a textile expert led to their ultimate exclusion from the dating operation. As the principal researchers on the object, their role should have been to take the samples, submit them to the lab, interpret and publish the results.

But the two major factors leading to the flawed C-14 plan were:

1) the insistence of the C-14 lab directors on taking control of the process, and
2) the equally stubborn insistence by the Archbishop's scientific adviser to
limit the operation.

The lab directors' over-riding and overly stressed concern was to be able to exclude any possible outlier result. To this end they insisted initially on five, then seven, labs participating in the dating. The scientific adviser, on the other hand, was adamant that only the absolute minimum amount of material be removed from the Shroud. The final outcome of this conflict was that only three labs were selected for the dating, and only one sample was taken and splits from it delivered to the labs.

It is frequently reported that the original C-14 protocol drawn up at the Turin conference of 1986, jointly sponsored by the Pontifical Academy of Sciences and the Turin Archdiocese, was to have seven samples from seven different sites on the Shroud. This is incorrect. At that conference a rough compromise emerged with the protocol calling for seven samples to be taken but from only ONE sampling site. The lab directors rejected the strong resistance on the latter point from a few individuals at the conference, because in the directors' view having two or more sampling sites increased the possibility of an outlier. They sought at all costs to have a result supported by the largest possible number of labs, primarily for public consumption.

The scientific adviser later unilaterally reduced the number of labs to three, but retained the proposal to take only one sample for dating. This was the most serious and fundamental error in the planning of the C-14 test. Proper archaeological dating would NEVER rely on a single sample, due to the occasional occurrence of aberrant results on "rogue" samples, for reasons that usually remain unknown.

Other serious errors in the planning included:

--the failure of the scientific adviser to consult properly on the choice of sampling site (it being decided only on the day when the sample was to be taken)
-- the failure to conduct ancillary tests on the sample site (although this was in the original protocol to be conducted by STURP, it was blocked by the lab directors)
-- the failure of the labs to carry out extensive chemical and physical screening of the samples prior to pretreatment and measurement.
Other aspects are also frequently cited as casting doubt on the result, such as the failure to include a lab using the traditional counting method, or the failure to adhere to the blind testing procedure. These are very minor considerations and do not have any impact on the final result obtained.

To reiterate, the FUNDAMENTAL flaw in the C-14 dating of the Shroud was the decision to take only ONE SAMPLE. That decision was made at the 1986 Turin conference and it was supported by the C-14 lab directors and the Archbishop's scientific adviser over the objections of others. The reduction of the number of labs from seven to three was of little significance.
--- William Meacham, Hon. Research Fellow, Centre of Asian Studies, University of Hong Kong
The planning of the C-14 dating of the Shroud is described in detail in the book "The Rape of the Turin Shroud" by William Meacham, pages 52-98.

Issues Arising from the Carbon Date

Alternative Interpretations

Since the Carbon 14 dating of 1988 dated the shroud to the late 13th or early 14th centuries there are only two constructions of this finding: 1) The Shroud of Turin is a product of the 13th and 14th century, or 2) the date is mistaken for some reason. Unless there was an instrumentation mistake which is extremely unlikely since three independent laboratories tested the shroud sample, the only explanation if the shroud is actually first century is one of C-14 enrichment through some contamination mechanism. Unfortunately the protocol agreed upon called only for a single sample site which left open the possibility of a rogue sample. Since only a single sample site was chosen and that sample cut into a reserve and several pieces for the C-14 laboratories the possibility that the sample is not representative of the whole Shroud cannot be ruled out. If on the other hand, the shroud is actually of 13th or 14th century manufacture the mystery of how it was produced remains.

Establishing Contamination

The positive test for vanillin as well as the presence of cotton actually spliced to linen and tinted as discovered by Ray Rogers establishes that the sample site selected for the 1988 C-14 test was anomalous and moreover that it was young. The reasons for this have not been firmly established. One theory set forth by Joe Marino and Sue Benford is that the site contained an invisible patch. This thesis is controversial, however it currently constitutes the main theory for why the region is anomalous.

STATISTICAL ANOMALIES IN THE CARBON DATING


Easy statistics.
When preparing for the Olympic Games, athletes know the limit for qualification. One has to run the 100 meters in 10 sec.
One running 10.1 sec. is not qualified for Peking.

In statistics, the limits are precisely tabulated.
When between 3 labs, one asks for 95 % confidence, the limit is a Chi² value of 5.99. In Table 2 (Nature 16-02-1989) one reads for the Shroud: Chi² = 6.4 In reality the Chi² value is 8.56.
The experts of the British Museum, the peers judging the paper in Nature and also the Experts of Turin, are disqualified for the Olympic Statistics.

By sheer co-indicence, the statisticians Wilson & Ward give an example of a Chi² test case.In "Archaeometry" (N) 20 1978) they wrote on page 26:"..three independent measurements on a single piece of wood (4330 190²) (4560 210²) ( 4940 300²), it is found that Ap 4525 V(Ap) 128² and T = 2.99 < 5.99and there is no evidence to reject the null hypothesis that the observations are consistent.We just have to change the data, substituting:
"In the case of the Shroud, three independent measurements on a single piece of linen (750 30²) (676 24²) (647 31²) it is found that Ap 689 V(Ap) 16² and T = 6.4 > 5.99 and there is evidence to reject the null hypothesis that the observations are consistent.
Note that a computer program gave Ap 672 1(V(Ap) 13² and T = 8.56

The Conclusion: The samples are not homogeneous.One has to examine the chemical composition of the linen.

- a brief account by Remi Van Haelst see also http://www.shroud.com/vanhels3.htm

More Discussion:
Among the various mistakes reported in Nature paper the most important is described in the following sketch: the Arizona result is NOT statistically acceptable (G. Fanti).

errC14.jpg

TECHNICAL PAPERS:

I encourage members to add to this list of papers with a brief comment on the character of the paper.
http://www.shroud.com/meacham.htm Paper written in 1986 which anticipated many of the C-14 dating issues.
http://www.shroud.com/vanhels5.pdf A critique of the C-14 dating data analysis.
http://www.shroud.it/ROGERS-3.PDF Is Ray Rogers' landmark paper which establishes that the C-14 sample region was anomalous.
http://www.shroud.com/pdfs/benfordmarino.pdf Paper on the Benford/Marino invisible weaving thesis.
http://www.shroud.com/pdfs/brown1.pdf John Brown's paper "Microscopical Investigation of Selected Raes Threads From the Shroud of Turin".