Scientific hypotheses on the origin of the body image of the Shroud
First results of experiments with ultraviolet light done with laser in the ENEA laboratories
by Paolo Di Lazzaro
The working group that conducted the experiments. From left to right: Daniele Murra, Paolo Di Lazzaro, Giuseppe Baldacchini [© ENEA]
Most scientific information on the Turin Shroud, a linen cloth 4.4 meters long and 1.1 meters wide on which a faint front and back image is visible of a supine man, come from in-depth physical and chemical analyses conducted in 1978 by a team of scientists, mostly American under the auspices of the Shroud of Turin Research Project (STURP) who were allowed to make optical, X-rays, ultraviolet and infrared tests, to take samples of dust and surface fibrils. The STURP analysis results were published in the early eighties in major international journals in their respective scientific fields, particularly in the American journal Applied Optics. In summary, the STURP scientists have demonstrated (in contrast to altogether fanciful theories that unfortunately still circulate on the subject, especially in persistent unscientific media scoops) that the Shroud is a very old linen cloth, with traces of blood, burns, stains caused by water, pollen and soil residues. The co-presence of blood, human serum and bilirubin (a yellow-red pigment contained in bile that the body produces under extreme trauma) leads to the conclusion that the cloth wrapped a dead man, who had suffered severe traumas. The position of the blood stains also shows that death occurred, after beatings and torture, by crucifixion, and corresponds exactly with the passion and death of Jesus of Nazareth as described by the Gospels.
Over the bloodstains, undoubtedly generated by contact with the body, the “stratigraphy” highlights the successive overlay of a weak yellowish image that now yields to view the features of a human body. The consecutio bloodstains - body image is evident since below the areas of blood stains the image does not exist.
According to the STURP results, this body image has about forty physical and chemical characteristics, that are very peculiar and practically impossible to reproduce with today’s technology, as well as (obviously) in the Middle Ages or in ancient times. The STURP excluded the possibility of its being a painting, or an imprinting with a bas relief heated or treated with pigments or ferrous powder. Rather, the image appears to result from a chemical reaction of dehydration of the outermost part of the fibrils of the linen threads, accompanied by oxidation. In practice, the image results from an accelerated aging of the linen from unknown causes. Also very interesting are the topological characteristics of the image of the face, which lead to the conclusion that the image did not occur through contact, since in that case the imprint would be enlarged, and not perfectly proportioned as it is. An additional and distinctive feature is that the shades of color of the image contain three-dimensional information.
In 1988, ten years after the STURP analysis, a small piece taken from one corner of the Shroud, divided into three portions, underwent dating by isotope C- 14. The result of the test, conducted in parallel by three of the best laboratories at the time, was a dating between 1260 and 1390 A.D. That would place the Shroud (or at least the sample examined) in medieval times. But it is worth pointing out that carbon dating (a method that, because it is statistical in nature and depends on many variable factors, is always used by archaeologists along with a whole complex of factors, including the historical ones, when dating an object) has given a dating for the cloth incompatible with the chronology suggested by data and indications of an historical, iconographic and textile-history nature, that concur on a much earlier dating of the Shroud. Some recent analyses suggest that the sample analyzed by C-14 may not be representative of the Shroud, and that the analysis itself may be vitiated by material errors in calculation.
Aims of the research
Determining the age of the Shroud has not been the aim of the research done in recent years by the ENEA work group coordinated by the writer, nor did it aim at analyzing the Shroud as a whole or in all its various aspects and problems, but focused only on the problem of the formation of the front and back image of the body. In short it aimed at answering the main question: “How was the body image on the Shroud formed?” No one, to date, even among the many researchers who have reproduced images macroscopically similar to that of the Shroud, has been able to reproduce an image that had all the particular physical and chemical characteristics that can be brought out by microscopic analysis and the same techniques of optical investigation used by STURP.
In 2005 we noticed that under the microscope some of the linen threads that make up the image of the Shroud showed a morphological structure similar to that obtained by irradiating different textiles with ultraviolet laser light (a procedure that we were testing for industrial purposes: surface finishing, iridescent effects, etc.).
The laser (an acronym for Light Amplification by Stimulated Emission of Radiation) is a complex tool, capable of generating continuous light or very short pulses of light in the order of billionths of a second. Laser light has completely different characteristics from the light emitted from a normal bulb, because it is coherent, i.e. all the emitted photons have the same characteristics: same color (monochromatic light), same spatial behavior, i.e. they all move in the same direction (directional light) and if they are spatially compressed can reach extremely high levels of intensity, up to many billion watts per square centimeter of surface, and even more.
Materials hit by laser light undergo a change in structure that depends on the spectrum, intensity and duration of the light. One of the properties of ultraviolet laser light (ultraviolet light is an invisible electromagnetic radiation with a wavelength shorter than visible light, but longer than X-rays) is that it penetrates very little into materials, including fabrics. And one of the characteristics of the Shroud image that is most difficult to reproduce is the extreme shallowness of the color: in fact every thread of linen, which has a diameter of about 0.3 mm, contains about two hundred fibrils (fibers of elementary cylindrical structure), and the colored part penetrates into the outer fibril only in the so-called primary cell wall, a very thin film 0.2 thousandths of a millimeter thick. It is so small a thickness that it is difficult to imagine.
So we thought it was a good idea using excimer lasers (because they emit more power in the ultraviolet range) to generate a shallow coloration of linen fibres. We bombarded various linen fabrics, both raw and bleached, of recent manufacture but made using ancient techniques, such as the hand loom, with pulses of ultraviolet light from our excimer lasers. Not finding any report of any attempts to color linen by ultraviolet laser light, we varied all the laser parameters (duration, intensity, number of consecutive pulses) over a wide range of values. This procedure took about two years to be completed.
EFFECT OF LATENT COLORATION
The top strip shows linen irradiated with laser intensity lower than the threshold value to produce the coloration. The right part was heated at 190°C for 15 seconds to get artificial aging (dehydration), and shows staining in the irradiated area; the bottom strip shows the same tissue a year later: even the unheated (left) part shows staining with natural aging [© ENEA]
The results went beyond our expectations. We have shown that an extremely short pulse of ultraviolet light (a few billionths of a second) in a very narrow range of values of energy and power density can color linen fabric with the same chromaticity as the Shroud image. Locally we managed to color, as we wanted, only the first layer of fibrils exposed to laser light, i.e. the primary cell wall, leaving the inside of the fibril uncolored. We also noted that a small increment of the intensity was sufficient to obtain a much deeper coloration depth than 0.2 micrometers, though still superficial. Whereas an infinitesimal reduction in intensity fails to produce coloration, or, as we have shown, the color becomes “latent”, i.e. it is invisible in the moment, but appears after more than a year’s aging.
This is the first time that, by analogy with the image on the Shroud, only the “primary cell wall” of linen fibrils has been colored by radiation, a result never so far obtained with chemical contact methods (dyes, chemical paste, powder, acids, vapours, etc.) and approached only by the “corona discharge” technique (the “corona discharge” is a phenomenon whereby an electric current flows between a conductor at high electric voltage and the surrounding air without causing an arc, the ionized air emits visible and ultraviolet radiation), as shown by Giulio Fanti of the University of Padua, with whom we are collaborating on this research.
A measure of the impact caused by the results is the fact that the first article describing them was published in March 2008 in the well known scientific journal Applied Optics (the monthly of the Optical Society of America in Washington, in which the STURP results were published)1, many years after the last article on the Shroud published by the same magazine. In fact, since the C-14 dating the major scientific journals, adopting an attitude of extreme caution, have refused to publish articles on the subject, and only a sensational result could get through. Our results were presented formally at two international conferences, the “High-Power Lasers” held at the University of Lisbon2 and “The Shroud of Turin: Perspectives on a multifaceted Enigma” held at the University of Columbus, Ohio (USA) in August 20083, and the most recent results are now in the process of publication by The International Journal of Imaging Science and Technology4.
These notes have also been presented and discussed at the IWSAI (International Workshop on the Scientific Approach to Acheiropoietos Images) held in Frascati from 4 to 6 May 20105.
Though significant, our results allow the recognition of a photo-chemical process capable of generating a Shroud-like coloration, but still do not make it possible to formulate a certain and practicable hypothesis on how the Shroud image was formed: for example, if we consider the density of radiation that we used to color a single square centimeter of linen, to reproduce the entire image of the Shroud with a single flash of light would require fourteen thousand lasers firing simultaneously each on a different area of linen. In other words, it would take a laser light source the size of an entire building.
For now, we can only say with certainty that our Shroud-like coloration result, within the limits of the available instruments, is perfectly reproducible in the laboratory. We have checked the results several times carefully. Consequently, our result is a scientific result for all effects and purposes.
1 G. Baldacchini – P. Di Lazzaro – D. Murra – G. Fanti, Colouring linens with excimer lasers to simulate the body image of the Turin Shroud, Applied Optics, vol. 47, p. 1278 – 1283 (2008)
2 P. Di Lazzaro – G. Baldacchini – G. Fanti – D. Murra – A. Santoni, Colouring fabrics with excimer laser to simulate encoded images: the case of the Shroud of Turin, XVIII International Symposium on Gas Flow, Chemical Lasers, High Power Lasers, edited by R. Vilar, Proceeding SPIE, vol. 7131 (2009), p. 71311R-1 – 71311R-6.
3 P. Di Lazzaro – G. Baldacchini – G. Fanti – D. Murra – E. Nichelatti – A. Santoni, “A physical hypothesis on the origin of the body image embedded into the Turin Shroud”. Proceedings of the International Conference on The Shroud of Turin: Perspectives on a Multifaceted Enigma, edited by G. Fanti (Libreria progetto editions, Padua 2009), p. 116 – 125.
4 P. Di Lazzaro – G. Fanti – D. Murra – E. Nichelatti – A. Santoni – G. Baldacchini, Deep ultraviolet radiation simulates the Turin Shroud image, Journal of Imaging Science and Technology, presently being printed (August 2010)
5 P. Di Lazzaro – G. Fanti – D. Murra – A. Santoni – G. Baldacchini, Submicrometer coloration depth of linens by deep ultraviolet radiation, a study undertaken at the invitation of the International Workshop on the Scientific Approach to the Acheiropoietos Images (IWSAI, 4-6 May 2010, Enea Center of Frascati).