What is Wrong with the Carbon 14 tests on the Shroud of Turin?
One cannot say definitively that the carbon 14
dating of the Shroud of Turin has been proven wrong, but now with new
year 2002 information one can honestly say that the dates are
no longer reliable indicators of the Shroud's age.
According to
the 1988 test
results, it was not, as so many believed, the authentic burial Shroud
of Jesus.
It was medieval. Nature, the prestigious international weekly journal
of
science, published an article about the test coauthored by twenty-one
scientists
from the University of Oxford, the University of Arizona, the Institut
für
Mittelenergiephysik in Zurich, Columbia University, and the British
Museum. The
conclusion in Nature was clear:
The results of radiocarbon measurements at Arizona, Oxford and
Zurich
yield a calibrated calendar age range with at least 95% confidence for
the linen
of the Shroud of Turin of AD 1260 - 1390 (rounded down/up to nearest
10 yr).
These results therefore provide conclusive evidence that the linen of
the Shroud
of Turin is mediaeval.
A headline in the New York Times read: "Test Shows Shroud of Turin to
be Fraud."
Other newspapers around the world reported similar conclusions. One of
the
radiocarbon dating scientists from Oxford stated on public television:
"We have
shown the Shroud to be a fake. Anyone who disagrees with us ought to
belong to
the Flat Earth Society."
But, to many people, the carbon 14 test results only made the Shroud
all the
more puzzling and all the more fascinating. There was, after all, a
preponderance of other scientific and historical evidence that argued
that the
Shroud was really much older. Some of the evidence suggested that it
had been in
Constantinople at one time, in the ancient Christian community of
Edessa before
that, and in the environs of Jerusalem. Science and history seem to
agree on
this.
The carbon 14 tests, conducted by three of the most
reputable radiocarbon dating laboratories in the world, have since been credibly
challenged, sufficiently so that they can no longer be deemed definitive. The
laboratories did the tests properly. There is little doubt about that. But there
is now serious evidence that the samples cut from the Shroud and provided to the
laboratories were contaminated. We cannot blame the labs. They had no way of
knowing.
It may have been the fault of the Poor Clare nuns who mended the cloth in the
16th century, or of some master weaver in their employ who wove new thread into
the cloth during repairs. We know from repaired tapestries how skilled medieval
weavers were at the art of "French Weaving," what is now commonly called
invisible weaving. Warp and weft threads were even spun by hand and dyed to
match the original thread of a tapestry.
Enough newer thread has been identified by numerous textile experts to allow
Beta Analytic, the world's largest and probably most prestigious radiocarbon
dating firm, to estimate that the true date of the cloth's origin is much older
- within a statistically acceptable margin of error to make the first century
possible. Beta Analytic estimates that a mixture of 60% of material, from the
16th century, with 40% of material from the 1st century would yield the medieval
date that was determined for the Shroud. Chemist Raymond Rogers has found a
rubbery vegetable substance, probably gum arabic, on threads adjacent to where
the carbon 14 samples were taken. It was common practice to use gum arabic to
hold threads during weaving repairs. It is significant to note that Rogers found
dyes extracted from the Madder root used with the gum arabic. According to
Rogers, "They were colored for a purpose using technology that was not used in
Italy before the 13th Century or in France before the 16th Century, about the
time the time the Shroud was moved to Turin from France." Rogers has also found
a spliced thread, likely of old and new material, among sample threads.
It is interesting to note that an article in Textile Horizons by P. H. Smith,
entitled "Rogue Fibers Found in Shroud," was published in 1988 that speaks of
the discovery of "a fine dark yellow strand [of cotton] possibly of Egyptian
origin, and quite old . . . it may have been used for repairs at some time in
the past, or simply bound in when the linen fabric was woven." This cotton was
found by Smith while examining samples on behalf of the Oxford laboratory. This
is important information.
In a new and very decisive paper on the subject,
Scientific Method Applied to the
Shroud of Turin: A Review
Raymond N. Rogers, a Laboratory Fellow at
the University of California, Los Alamos National Laboratory and Anna
Arnoldi of the University of Milan write:
The combined evidence from chemistry, cotton content,
technology, photography, and residual lignin proves that the material of the
main part of the Shroud is significantly different from the radiocarbon sampling
area. The validity of the radiocarbon sample must be questioned with regard to
dating the production of the main part of the cloth. A rigorous application of
Scientific Method would demand a confirmation of the date with a better
selection of samples.
The newer thread or gum arabic, or some combination of the two, may be enough to
skew the date by enough centuries to make the Shroud a first century cloth.
There is no way to calculate a revised age from the test records. Because carbon
14 testing destroys the samples, there is also no way to redo the tests. It is
also unlikely - and reasonable - to doubt that the Vatican would allow new
carbon 14 tests unless a clear, failsafe, and non-controversial testing protocol
can be established. That is unlikely in the foreseeable future. But the clear
evidence of substantial contamination is enough to call the carbon 14 results
into question. They can no longer be thought of as definitive.
An open letter to John Dominic Crossan,
Dear John, What Were You Thinking?
goes into more detail about carbon 14 dating problem.
Other web pages address some of the
other evidence that argues that the Shroud of Turin Carbon 14 testing
does not make sense:
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