Saturday, January 7, 2012

The Turin Shroud elicits ever more bad science... which the media dutifully reports as cutting-edge...

Why did those Italian scientists choose the uv region of the spectrum to model their improbable hypothesis for the Turin Shroud's image?

Nothing, apart from the Blair/Brown legacy,  infuriates this retired scientist more than seeing New Age so-called scientists straying over the line between science and religion. Yet that is what a group of Italian scientists have done in spectacular fashion. What’s more they have done it in such a manner as to create confusion and misunderstanding as to precisely what role they see for (wait for it) supernatural processes having produced the image, allegedly of the crucified Christ, on the Shroud of Turin. 

On the one hand their spokesman says he is unwilling to go beyond the science, yet that is precisely what he proceeds to do with his references to “philosophy and theology”. OK, so he is not the first to do that – Stephen Hawking did so in his “Brief History of Time”, but he is a cosmologist who, usually in the absence of hard data, and dependent as he is on mathematical modelling,  has to think the unthinkable.  The Turin Shroud, on the other hand is a physical object, much damaged by the 1532 fire, the subject we are told of repair processes (that have conveniently “falsified” the carbon dating of 3 independent laboratories due we are told to contamination)  yet here we have scientists speculating, yes speculating on intense flashes of ultraviolet light with all the implied supernatural intervention from on high..

Is this objective science?  I say no. It’s in the same league as Uri Geller’s spoon-bending (and I say that in the knowledge there are those who still think that was “magic”, as distinct from a conjurer’s trick, using  suggestion, distraction etc.).

Why did those Italians - ostensibly employed to research new technology in the public sphere -  break off to beam ultraviolet light from a laser at linen?  Why that particular region of the electromagentic spectrum (see diagram) , given that whatever findings they made, or claim to have made, there would be the inevitable conclusion that no medieval forger had access to a coherent beam of uv light? Does it not sound like a placing of a conceptual cart in front of a well-flogged,  indeed knackered horse?  Their credo is  "Let’s discount any technology that was available to medieval forgers , because it would be unable to simulate the peculiar properties of the shroud revealed by 20th century science – the superficiality of the image on the cloth, its appearance on the reverse side too (whether cloth of individual fibrils is not clear)?  Let’s skip a whole raft of experiments that might be performed with accessible regions of the em spectrum, notably non-coherent infrared, visible or uv light, with or without the presence of putative photosensitizers".  (See note at bottom re importance of photosensitizers in any discussion of cellulose and ultraviolet radiation)*. You know the sort of thing:  certain drugs in the body -  tetracyclin antibiotics, statins etc. - can sensitize certain susceptible folk to uv rays from the sun, producing phototoxicity, skin lesions etc.  How can those Italians be so certain that there is not a more mundane explanation for that faint sepia image on the shroud. Why rush straight to a uv light, and state-of-the-art coherent uv light at that, from a laser, with all the wave peaks and troughs in perfect hi-tech step?

Here’s a question to ponder: why even contemplate uv light as a candidate for producing superficial images on fabric?  That flies in the face of what we know about the interaction between uv light on organic molecules. Ultraviolet light covers a range of frequencies whose energy corresponds with the bond energies (C-C, C-H, C=O, O-H etc) in organic molecules. In other words, uv light causes those bonds to rupture - by promoting electrons to higher non-bonding molecular orbitals – resulting in reactive free radical being formed – i.e. atoms or functional groups carrying an unpaired electron.

Uv light penetrates to the very heart of molecules, breaking them up from within.  Think of it like a torpedo aimed at a warship’s store of weaponry. That’s as distinct from infrared rays say, say, which do not carry enough energy to break bonds directly. What they do is cause  chemical bonds (shared pairs of electrons)  to vibrate in various modes, not break, but a small proportion of that energy can so agitate molecules as to make some collide. If the collision energy exceeds the activation energy required for chemical reaction (needing bonds to be broken before new ones can be formed) then infrared radiation can producing the kind of reactions that producing scorching (dehydration, chemical condensation reactions etc).

These days one sees the expression “to beg the question” used wrongly to mean “to invite the question” when it really means to give a response that merely rephrases the question in a different form, e.g. "Opium induces sleep because it has a soporific quality”.

Those Italian scientists have (temporarily I hope) forsaken the objectivity that is expected of scientists. Their beaming of ultraviolet rays at cellulose - and the way they have reported their results to the media - in order to preempt or dismiss  other scientists is, to put it mildly, merely “begging the question”.

"Cellulose undergoes auto-oxidation in the presence of UV radiation  leading to bleaching of the surface. Cellulose itself does not absorb UV, however, lignin, hemi-celluloses and some dyes and pigments act as photo-sensitizers. (Photo-sensitizers absorb UV radiation and transfer the energy to the cellulose, initiating a reaction.)  As a result some of the long molecular chains break up, lowering the degree of polymerisation, and weakening the material."

Taken from: link 

It is important to keep this is mind when one reads of so much emphasis, possibly over-emphasis on the Shroud image being superficial, exceedingly thin, or present on opposite faces of cellulose fibres/fibrils but not in between. Any photodynamic action involving visible or uv light is likely to be confined to a very small distance from the interface between putative photosensitizer and cellulose. 

In my recent previous posts (see link to posts with the keyword thermo-stencilling), I have described the use of "charcoal paint", subsequently washed out after heat-irradiation, to produce a thermo-stencil. It has just occured to me that the charcoal might be described as a "thermosensitizer", producing a highly localised scorch mark. A thermosensitizer would be to the infrared region of the em spectrum what a photosensitizer would be to the visible or uv regions. 

Did the production of the Shroud image require the presence of sensitizer? If so, was it a photosensitizer or thermosensitizer?

1 comment:

sciencebod said...


Since this post was written, this blogger/retired science bod has proposed a more comprehensive theory as to how the Shroud was created in the 14th century as a ‘holy relic’. The essence of the theory is the making of a thermo-stencil, using linen impregnated with a heat-sensitive chemical substance or cocktail, from a partially-mummified, minimally-skeletonised cadaver possibly in a monastery (think Brno). The desiccated proxy for the crucified Christ would have been heated in an oven of some kind, until radiating sufficient infrared as to be capable of leaving an image on thermo-sensitized cloth.

link to mummy theory