March 21, 2008 -- The Shroud of Turin, the 14- by 4-foot linen believed by some to have been wrapped around Jesus after the crucifixion, might not be a fake after all, according to new research.
The director of one of three laboratories that dismissed the shroud as a medieval artifact 20 years ago has called for the science community to reinvestigate the linen's authenticity.
"With the radiocarbon measurements and with all of the other evidence which we have about the shroud, there does seem to be a conflict in the interpretation of the different evidence," said Christopher Ramsey, director of England's Oxford Radiocarbon Accelerator Unit, which carried out radiocarbon dating tests on the cloth in 1988.
Venerated by many Catholics as proof that Christ was resurrected from the grave, the yellowing cloth is kept rolled up in a silver casket in Turin's Cathedral.
Shroud Science: Chapter One
Scientific interest in the linen, which has survived several blazes since it was discovered, began in 1898, when it was photographed by lawyer Secondo Pia. The negatives revealed the image of a bearded man with pierced wrists and feet and a bloodstained head.
In 1988, three reputable laboratories in Oxford, Zurich and Tucson carried out radiocarbon tests on the cloth and declared it a brilliant, medieval fake produced between 1260 and 1390.
Nevertheless, the piece of linen made of fine, tightly woven herringbone twill has remained an unquestioned object of veneration. When it last went on public display in 2000, more than three million people saw it. Many more visitors are expected for next public display in 2025.
Shroud scholars, known as sindonologists, have always argued that no medieval forger could either have produced such an accurate fake or anticipated the invention of photography.
Yet, despite arguments and claims of revisionist scholars, all theories on how the radiocarbon tests could have been inaccurate have been rejected by the scientific community.
A Question of Contamination
In this latest chapter, Ramsey's call to revisit the subject follows tests taken by Ramsey, himself, to investigate a contamination hypothesis by John Jackson, a U.S. physicist who conducted the first major investigation of the shroud in 1978.
Jackson, the director of the Turin Shroud Center in Colorado, has long claimed that a 1532 fire which damaged the cloth may have affected procedures used to date the shroud.
Based on information about C14 dating that wasn't available 20 years ago, Jackson's theory suggests that only a two percent contamination could skew results by 1,500 years.
The details of this collaboration are reported in a documentary to be aired by the British Broadcasting Company on Saturday.
Meanwhile, a new study, published in the book "La Sindone, una Sfida alla Scienza Moderna" ("The Shroud, a Challenge to Modern Science"), by Giulio Fanti, further supports Ramsey's call for revisiting the carbon-14 tests.
"The study, carried out by the researcher Gerardo Ballabio of the Shroud Science group, does add a new twist. It looks at a less known aspect of the C14 tests: how the linen sample was divided into sub-samples by the three laboratories who performed the radiocarbon tests in 1988," Fanti, a professor at Padua University in Italy, told Discovery News.
"Basically, it is a re-analysis of the available data which takes into consideration the spatial positions of the sub-samples on the shroud. It shows that the 1988 statistical results are not correct," Fanti said.
The Shroud in Puzzle Pieces
A previous study by Bryan Walsh, director of the Shroud of Turin Center in Virginia, suggested that differing levels of cabon-14 were present when examining the horizontal positions of sub-samples from the shroud. But the question of whether a gradient also existed in the vertical direction remained open.
It is known that the samples distributed to each lab in 1988 were first cut from a corner of the shroud. Basically, the sample consisted of an 81- by 16-mm rectangle weighing 300 mg. The rectangle had a missing corner as a result of a previous sample extraction.
"This piece of linen was split into two parts. One was divided into three samples to be given to the laboratories, and another was retained in case further material was necessary. Since one of the three samples was significantly smaller than the others, a thin section from the retained part was added to the smaller sub-sample," Ballabio said.
The samples were sealed, documented and forwarded to the labs along with control samples for testing and evaluation. The laboratories in Oxford and Zurich were each given one of the single-piece samples, while the laboratory in Arizona was given the two-part sample.
What happened later is a subject of controversy, according to Ballabio.
"Each lab subdivided the sample in various pieces, making it a puzzle to reconstruct their original position on the shroud," Ballabio said.
In order to reconstruct how the samples were cut, their physical positions on the shroud, and the lab measurements for each sub-sample, Ballabio collected information from many key people involved in the testing operation.
"I ended up with 256 possible combinations," Ballabio said.
Differing Conclusions
The researchers performed a statistical analysis which involved each of the 256 configurations and concluded that there is a strong difference in the 14C concentration of the small rectangle used in the tests, with the upper-right corner being about 300 years younger than the lower left corner.
According to Ballabio, the study shows that the sample must have been substantially contaminated.
"The statistical tests performed by the labs assumed a 14C homogeneity in the samples, but my statistical evaluation shows exactly the opposite and puts into serious question the validity of the dating. Since a 300-year difference is present in a few square inches, one must wonder how this data translates into a 14- by 4-foot-long linen," Ballabio said.
According to Raymond Schneider, assistant professor of mathematics and computer science at Bridgewater College in Virginia, Ballabio's paper might be an important new contribution to support the request for new tests on the shroud.
"I have not seen Ballabio's paper, but if he really succeeded in improving the estimation of any gradient present, we can say that there are serious and compelling reasons to consider the sample site anomalous or contaminated or both," Schneider told Discovery News.
For his part, Ramsey, an expert in the use of carbon dating in archaeological research, is keeping an open mind toward the new hypothesis.
"Everyone who has worked in this area, radiocarbon scientists and all of the other experts, need to have a critical look at the evidence that they've come up with in order for us to try to work out some kind of coherent story that tells us the true history of this intriguing cloth," he said.
Related Links:
Rossella Lorenzi's blog: Archaeorama