Resurrecting the authenticity of the Shroud of Turin

Fibrils from one of the image areas of the Shroud.

Just when you think you’ve debunked a religious artifact good and proper ….

Many people who only know that the Shroud of Turin is alleged to be the burial shroud of Jesus Christ were happy to accept the 1988 carbon-14 dates — 1260 to 1390 — without further question, and not all of them were atheists or anti-Christians. Many Christians would find a Christ who actually rose from the dead to be upsetting; they much prefer the Resurrection as a psychological metaphor rather than as an historical fact. So the “medieval forgery” became the Accepted Wisdom quite easily, despite later stories concerning the integrity and scientific value of the tests.

Those who knew anything more about the Shroud — I’m not a qualified sindonlogist myself — weren’t happy with the results, for reasons having nothing to do with religious faith. The fact is, no one has come up yet with a plausible explanation for how the image on the Shroud was formed given the technological limitations of the 13th and 14th centuries. None of the techniques suggested to date, and some have been rather inventive, would leave an image with the physical and chemical characteristics known of the Shroud; in fact, no one’s had luck reproducing the Shroud with 21st-century tech. Frankly, at this point Erich Von Däniken’s aliens can look like a more credible explanation for the Shroud than some anonymous High Middle Ages genius.

Tuesday saw the release of news about a series of three new tests, two chemical and one mechanical, carried out by “a number of professors from various Italian universities”, which point to a date of 33 BC ± 250 years. This puts 30 AD, the generally accepted year of Jesus’ death, well within the bracket.

Cue the protests.

Before going further, let me make my position clear: Even if the Shroud of Turin is precisely what it purports to be — and I for one believe it to be so — by no means does it provide conclusive evidence for Jesus’ resurrection or his divine provenance. The most it would prove is that something uniquely extraordinary happened to the body of a known historical person who claimed divine Sonship to God.

However, you know that someone — more than a few people,really — are going to brush off the tests: Italians are Catholics, and we all know that Catholics can’t do science. The so-called tests are simply wishful thinking while wearing lab coats.

I find it ironic that people who claim to be all about science, who demand experimental validation for every fact, will make such bigoted allegations about Catholics without a whisper of evidence and in complete ignorance of the history of science. Indeed, as Stacy Trasancos recently wrote, most such people merely have exposure to a “Whig history” of science that verges on self-serving mythos. And while it’s defensible to take a wait-and-see approach to the tests — they have yet to complete the peer-review stage — to dismiss the tests a priori as false because of their conclusion is characteristic of closed-minded dogmatism, not intellectual independence.

Now, what was wrong with the 1988 carbon-14 tests? Setting aside all the claims of partiality and breaches of protocol, we know that there are a couple of unique things about the Shroud that would have thrown off even a well-executed test.

First, the Shroud was exposed to a fire in 1532. Not only did melting silver leave large burns in the fabric, the fire essentially “youthened” the Shroud through a chemical process involving smoke, silver and water. Second, a scientist discovered a bacteria on the Shroud that as waste produced a polymer that previous scientists thought was Spandex; this biopolymer is extremely resistant to the chemicals used to wash samples prior to C¹⁴ dating.

Then there’s the method itself. Radiocarbon dating is not 100% reliable, sometimes giving date ranges that wildly diverge from estimates derived from other evidence. One of the theoretical bases of the process — the constancy of C¹⁴ levels relative to C¹² in the atmosphere over time — has not been confirmed; local phenomena such as forest fires and magnetic anomalies can affect the distribution. Ordinarily, if there were ten lines of evidence including radiocarbon dating, and the C¹⁴ date conflicted with the others, it would be the date tossed and not the one produced by the other lines.

Why, then, would anyone insist that the 1988 tests were authoritative? Part of it is that radiocarbon dating has been misrepresented in the popular press as the final arbiter. One of our curious modern assumptions is that technological instruments will always be more accurate and precise than a human’s best estimate, which can sometimes lead to over-reliance overwhelming common sense.

The other part is that wishful thinking isn’t a function of being religious but rather of being human. Atheists are subject to cognitive biases like anyone else. In fact, some, like Richard Dawkins, operate on a sort-of inversion of Anselm’s ontological argument: If there is a possibility that an event was brought about by natural means, then it must have happened naturally … even if odds against are insanely high.

So here’s the challenge of reproducing the Shroud: the chemical makeup of the topmost fibers of the Shroud were changed by oxidation, dehydration and conjugation of the long-chain sugar molecules — loosely speaking, they were caramelized. However, the penetration goes no deeper than about 200 nanometers. The color itself is monochromatic; the appearance of different shades comes from the different density of affected fibers to unaffected fibers.

This means that any explanation involving paint, dye, ink or any other suspended medium is wrong. Hot-metal scorching is out, because the penetration would be too deep and would char the material. Chemical vapors are also out, as they would at best create hazy, indistinct images; the image on the Shroud is sharp. Moreover, since there are no image fibrils underneath the blood stains, the challenge for an artist would be to put the blood on the Shroud and then create the image, getting the “body” in precisely the right spot to make it appear natural.

The most likely cause for such a transformation of the fibers is an extremely short yet extremely intense burst of radiation energy in the VUV range (vacuum ultraviolet; i.e., wavelengths less than 200 nm) … about 34 × 10¹⁵ watts to instantly color the area of cloth equal to the body surface of a human of average height, far more powerful than any VUV source currently manufactured.

Further than this, science can only speculate. For instance, we don’t know that the body was the source or transmission medium of the energy, though it’s even harder to explain otherwise without importing Von Däniken’s aliens, given the Shroud’s age. Thirty-four petawatts of energy could have possibly annihilated the body at the very microsecond the image was formed. Anything or nothing could have happened after that second.

Then again, it could very well be what it purports to be — a snapshot of the Resurrection.

It’s not the least likely answer. It’s just the least acceptable answer.