Cosmiclog/MSNBC

Italian researchers have resurrected the idea that the Shroud of Turin's mysterious image of a Christlike figure could only have been created by a powerful flash of light — but skeptics still aren't buying it.

Scientists have tussled with believers, and with each other, over the origins of the centuries-old cloth for decades: Many believers think it's the true image of Jesus, left behind miraculously on his burial cloths after his resurrection. Analyses of the Shroud's chemical makeup, as well as radiocarbon dating of fiber samples, have led lots of researchers to conclude that the image was painted onto the cloth during the 14th century. But other researchers, sympathetic to the Shroud's cause, say those tests were faulty.

The Italian studies, conducted at the ENEA Research Center in Frascati, addresses a specific question in Shroud science: Could a burst of radiation have created the coloration seen on the linen? The answer is yes, although the results reported in the latest studies aren't a perfect match. So does that mean the Shroud image could only have been created by the flash of a miraculous resurrection? The answer is no, despite what you might read on the Web.

Five years of tests
"Sadly, we have seen many claims spread in the Web made by journalist/bloggers that discuss the content of a paper they never read," lead researcher Paolo Di Lazzaro told me today in an email. "It is obvious that a serious scientific work cannot prove any supernatural action. We have shown that the most advanced technology available today is unable to replicate all the characteristics of the Shroud image. As a consequence, we may argue it appears unlikely a forger may have done this image with technologies available in the Middle Ages or earlier. The probability the Shroud is a medieval fake is really low. In this sense, the Shroud image is still a scientific challenge."

Di Lazzaro and his colleagues based their conclusions on five years of tests, using an ultraviolet laser apparatus and strips of modern-day linen. They blasted the cloth with UV at different power levels, and reported that they "achieved a very superficial Shroud-like coloration of linen yarns in a narrow range of irradiation parameters." The best effect depended on laser pulses lasting less than 50 nanoseconds.

"These processes may have played a role in the generation of the body image on the Shroud of Turin," the researchers report.

They don't go so far as to claim a miracle. But the fact that UV laser blasters didn't exist in the 13th century, let alone in Jesus' day, strongly implies that they suspect something out of the ordinary was going on.

Di Lazzaro told me that the tests were not financed by ENEA, which is a government-sponsored research agency, and were conducted outside working hours. "The research was curiosity-driven, the attempt to replicate an image which is considered 'the impossible image' due to its very peculiar characteristics," he said.

Over the years, Di Lazzaro and his colleagues have published a long list of studies, including peer-reviewed papers (see below). The latest studies were presented at a May conference in Frascati and published in November as an ENEA technical report (with a disclaimer saying that the contents didn't necessarily express ENEA's opinion). But they didn't really get traction until this week, just in time for Christmas, thanks to a series of sensationalized British news reports.

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Critiquing Shroud science
Shroud science, also known as sindology, usually percolates outside the scientific mainstream — but every once in a while a sensational claim comes into the public spotlight. Joe Nickell, an investigator for the New York-based Center for Inquiry, has been following sindology for decades. He noted that the Italian research revives a discussion going back to the 1980s, spearheaded by a group called the Shroud of Turin Research Project, or STURP.

"This is really nothing new," Nickell told me today. "This is a supposed vindication of STURP."

Nickell said Di Lazzaro and his colleagues started out with the assumption that the coloration on the Shroud couldn't have been created by applying pigment to the linen — which runs counter to the conclusions drawn by other studies. Starting out with the idea that the human figure shown on the Shroud is an "impossible image" stacks the deck in favor of a miraculous explanation, he said.

"Making the assumption of a miracle is a really, really, really, really, really big assumption," Nickell said. "That it's done in the name of science is just astonishing."

Nickell said the latest findings don't prove much of anything, even though they're dressed up in high-tech tests.

"It is made up of whole cloth," he said. "The pro-Shroud people start with the answer, and then they have to get some scientific evidence to back this up."

This week's chatter on the Shroud:

• ENEA: Shroud-like coloration of linen fabrics by vacuum UV radiation
• Int'l Workshop on the Scientific Approach to Acheiropoietos Images
• Telegraph: Study claims Shroud is Christ's authentic burial robe
• Daily Mail: The Turin Shroud DOES have miraculous powers