Science meets Religion:   Shroud of Turin

from Overcoming Prejudice in the Evolution Creation Debate by Dr R. Gary Chiang

4.2 The Shroud: A Primitive Photograph

Few skeptics of the Shroud actually accept McCrone’s evidence anymore, although at one time, this evidence was widely used to discredit a supernatural origin of the Shroud.   Instead, many skeptics now accept the fact first documented by Secondo Pia – the image on the Shroud is a photographic negative, not a painting.   And if the Shroud is considered to be a photographic negative, the next challenge is to devise a theory that explains in naturalistic terms how a photographic negative of a crucified man could have been imprinted on a piece of linen during the Middle Ages.

One of the more intriguing and imaginative theories to explain the photographic negative on the Shroud was described in a book by Picknett and Prince.8 These authors accept the fact that the image on the Shroud is a photographic negative.   If it is a photographic negative, then who in medieval Europe would have had the scientific knowledge, ingenuity, and the desire to produce this Shroud as a hoax?   The answer to their question: Leonardo da Vinci.   Assuming that da Vinci was dissatisfied with the church in one way or another, he produced the Shroud to play an elaborate joke on the church.

According to Picknett and Prince, da Vinci constructed a light-tight room with a small hole in one of the walls of this room.   He then obtained the body of a recently crucified man to ensure that the image of this body would be truly representative of the crucified Christ.   His next step was to hang this body in the sunlight directly outside of the light-tight room in front of the hole in one wall.   Constructed in this fashion, this room served as a very large pinhole camera in which the image of the crucified man was projected into the room through the hole.   This image was captured on a cloth soaked in a chemical that burned the cloth when the cloth was exposed to light.   The exposure time would have been relatively long since the material on the cloth was not very sensitive to light.   Therefore, to ensure a sharply focused image, the body needed to be turned continuously to account for the movement of the sun.   Once one side of the cloth was done (e.g. the front of the body), the cloth was flipped over, and the body turned to obtain the other side of the image.

The authors provide some scientific evidence of their own to show that such a picture can be produced with this technology, but compared to the image on the Shroud, their examples are far from the quality that was produced hundreds of years earlier.   To add credence to their theory, they also compared a self-portrait of da Vinci with the face on the Shroud, and they see a remarkable similarity. They conclude that, for the ultimate joke on the church, da Vinci removed the head of the crucified man and placed an image of his own face there.

This theory has received little attention from those who believe in the Shroud’s authenticity since it is absurd to the highest degree.   Conversely, it has been seriously considered by Shroud skeptics who simply cannot accept a supernatural origin for the image on the Shroud. In light of a lack of any other theory, this theory has gained credibility among the skeptics.

Unfortunately for the Shroud skeptics, there are many difficulties with the Picknett and Prince interpretation, one of which being the birthday of da Vinci.   Da Vinci was born in 1492; the Shroud appeared in recorded history in 1357.   For their theory to be correct, not only did da Vinci understand photography centuries before it was discovered, he also had to replace the original Shroud with a replica that he created, and this switch had to occur without being detected by those who were intimately acquainted with this relic.   First of all, one wonders what motive would have driven da Vinci to undertake such a deception, and second, why a scientist as gifted as da Vinci would not have developed photography to its full potential.   It is simply unimaginable that anyone like da Vinci would have remained silent about an work of art he created that even today scientists are unable to duplicate.   Nevertheless, as it is with the theory of evolution, this naturalistic theory of the Shroud has been given serious consideration because it does not require the existence of a supernatural force.   By having a totally naturalistic explanation, it is no longer necessary for skeptics to worry that a supernatural force could have created the image on the Shroud.

Although the Picknett and Prince theory is very, very weak, it does represent a significant change in the attitude of the skeptics.   No longer do these skeptics insist that the image on the Shroud is a painting.   This turnabout may have been encouraged by the fact that the radiocarbon dating showed “conclusively” that the Shroud was too young to have been around to wrap the body of Christ.   Possibly, with the assurance of the radiocarbon dating, the opponents of the Shroud have been more willing to concede that the facts are indeed overwhelmingly in favour of the image not being a painting.   Unfortunately for the skeptics, who had their day when the radiocarbon results were first reported, radiocarbon dating is not thought to be as conclusive as it once was.   It is quite possible that antique relics, like the Shroud, which have been exposed to everything from extreme heat and smoke to the touch of human hands, have too many variables associated with them to accurately determine their age using radiocarbon dating.