A week or two ago I wrote about the Shroud of Turin, after a new study by Italian scientists was trumpeted in the media as apparently showing it really was the burial cloth of Christ. Naturally, it did no such thing: it showed that marks similar to those on the Shroud could be made using ultraviolet light. It’s very interesting, but not proof of divine origin – especially in the light of radiocarbon dating results which put the Shroud at around 800 years old, which Prof Christopher Ramsey of the Oxford Radiocarbon Accelerator Unit tells me we have no reason to doubt.
After I’d written it, one of the lead authors of the Italian study, Dr Paolo Di Lazzaro, got in touch to ask for a correction, which I happily made (specifically, I’d said the authors claimed that their method was "the only" way the Shroud image could have been made – they didn’t). He also kindly agreed to a brief email interview about what he thought his study meant. I’ll reprint his answers in full below:
Full Interview: The Shroud of Turin: forgery or divine? A scientist writes
• You’ve been able to create very similar effects to the Shroud’s markings using ultraviolet light. Is this the most plausible way the original markings were made? What are the alternatives?
You are right: we obtained a coloration “similar” to that of the body image on the Shroud. “Similar” means that it replicates several peculiar characteristics of the Shroud image, including the shallow penetration depth and the hue of color, the lack of fluorescence, and the absence of heating effects on the image formation. However, our coloration still does not match 100 per cent of the physical and chemical characteristics of the Shroud image. Till now, nobody was able to replicate all the body image characteristics. This inability to repeat (and therefore falsify) the image on the Shroud makes it impossible to formulate a reliable hypothesis on how the body image was made. As a consequence, we cannot state ultraviolet light is the most plausible way the original marking was made. Certainly, the radiation-based attempts (ultraviolet light, corona discharge, protons) gave coloration results which are much closer to the Turin Shroud image than the contact paint or chemical attempts are. In particular, the recent results obtained by Prof Garlaschelli using acid, powders and paints show the incapacity of chemistry-based attempts to match the original characteristics at the microscopic level.
• It’s been reported that your research shows that the Shroud was not a "medieval fake". Do you agree with that assessment?
As discussed in the previous answer, all the attempts to replicate the body image on the Shroud were partially (often totally) unsuccessful. We must admit it is not easy creating an image that is negative, has 3D encoded information, is extremely shallow, with the color intensity is determined by the surface density of fibrils all having the same RGB value, and which does not fluoresce under UV illumination. Modern technologies seem unable to produce an image with the characteristics of the Shroud image, even using the most advanced tools like those used in our experiments. As a consequence, it is unlikely that a forger could have created this image using technologies available in the Middle Ages. In addition, we must consider the body image is not the only difficult-to-replicate marking. On the Shroud there are also stains of blood with high levels of bilirubin which would be consistent with a haemolytic process caused by torture, eg whipping (the bilirubin content being only visible by UV lamps, such as those used by policemen to detect organic traces), there is the absence of image under the blood stains, and many other forensic details unknown in the Middle Ages.
• When I spoke to Prof Ramsey, he said that the radiocarbon dating results putting it at 1260 – 1390AD were reliable, and that the suggestions of contamination or medieval repair were unlikely. Do you agree with that?
I have no experience of radiocarbon dating. As a consequence, I have to accept the opinion of Prof Ramsey. However, I note we have a problem: there is an object dated 1260AD that has a microscopic complexity such that it cannot be made by a forger in 1260AD. Does Prof Ramsey have any idea how to solve this contradiction? Can we collaborate to find a solution? Is it possible to organise a team of experts that reconsider both dating and microscopic characteristics of this extraordinary image?
• What is the significance of the Shroud if it is shown to be of medieval origin? Is it still a fascinating artifact even if it isn’t Christ’s burial cloth?
The significance of the Shroud for mankind was addressed by Pope John Paul II and more recently by Pope Benedict XVI. The best definition of the Shroud from a scientific point of view was by Pope John Paul II: the Shroud is a challenge to our intelligence.
• Do you personally believe that it is the Shroud of Christ?
As a scientist, I think we will never demonstrate the Shroud is the burial cloth of Christ. Even if it will be shown this cloth is of the first century, we will have a probability, never a certainty. However, I have studied more than 60 peer-reviewed papers on this topic, analysed a lot of microphotographs and microscope images, read sophisticated spectral information, and considered many other scientific data available. The more one studies the Shroud from a scientific perspective, the clearer it becomes that this image could not have been made by a forger, either medieval or modern. This allows to come back to the “question of questions”: how was the body image on the Shroud made?