According to tradition, the 14-foot by 4-foot Shroud of Turin is the linen burial shroud of Jesus. The shroud has a full-length photonegative image of a man, front and back, bearing signs of wounds that correspond to the Gospel accounts of the torture Jesus endured in his passion and death.
The church has never officially ruled on the shroud's authenticity, saying judgments about its age and origin belonged to scientific investigation.
Scientists who conducted on-site tests of the shroud in 1978 discovered that the image was not painted, drawn, printed or transferred on by heat and that the depth of coloration of the linen fibers is extremely thin -- equivalent to the top cellular layer of each linen fiber, according to ENEA's scientific report released in December.
The ENEA report said science has been unable to explain how the image on the shroud was created and attempts to recreate a similar image by chemical methods had failed "until now."
The five-person ENEA team used a laser to shoot nanosecond-fast pulsating beams of vacuum ultraviolet radiation or "extreme ultraviolet radiation" on a piece of linen cloth to create the same characteristics of coloration observed on the shroud -- that is, the same sepia tonalities and the same superficial depth of coloration, the report said.
The experiments also achieved the same peculiar trait observed on the shroud with the irradiated cloth no longer being phosphorescent under ultraviolet light, it said.
Another interesting find, the report said, was what happened when a hot iron was passed over pieces of cloth that had undergone just a small number of ultraviolet pulses and revealed no coloration: The dehydrating or artificial aging effect of the ironing ended up producing the same desired coloration seen on the shroud.
Similar pieces of cloth that showed no coloration because they, too, were not exposed to enough total intensity of UV radiation also developed the same coloration after they had been stored in a dark drawer for a year, it said.
This last result is particularly important, it said, because it introduces the possibility that the image created on the shroud could have become visible over time.
"We succeeded in getting a coloration of the linen that has both the tonality of color and the thickness of coloration that approaches (the properties seen) in the image formed on the Shroud of Turin," the report said. The coloration was also achieved without heat, which is compatible to findings discovered from the shroud, it added.
As a result, the researchers said, they have uncovered what could be the "distinct physical and photo-chemical processes that account for both coloration and latent coloration" due to dehydration from time or heat.
However, the ENEA experiments could only produce small dots of coloration on small swaths of cloth, it said.
No machine or energy source is currently capable of providing the total amount of power that would be needed to instantaneously color the entire image of an adult on a 14- by 4-foot piece of cloth, it said.
Also, they were unable to create the kind of color gradations that the shroud possesses, it said.
Given the "great technological and scientific difficulties" in producing similar colorations, the hypothesis that the shroud is a medieval fake "does not seem reasonable," said the report.