bill@utastro.UUCP (William H. Jefferys) (09/08/86)
Most of Mark's arguments are discussed in Nickell's book, _Inquest on the Shroud of Turin_. I urge anyone interested in the subject to read this book for balance, regardless of your bias, just as I have read many pro-authenticity books and articles. I don't see how anyone can be fully aware of all of the issues involving the Shroud if they have read only materials favorable to one side of the controversy. Arguing without sufficient background is arguing in a vacuum. Indeed, it is rather discouraging to see the same arguments raised over and over again. There's not much incentive for me to continue to contribute to this discussion unless others are willing to put in some time to read about the skeptical side of the issue. I don't mean to imply that Nickell's book is the last word on the subject; but it explains well why arguments like the ones in Mark's article are unlikely to impress skeptics who have seen most of them many times before. Since I have finished writing this, I will post it. But I am going to put down the chapter numbers in Nickell's book where you can find each topic discussed. Next time I may just post the chapter numbers. > But were the quantities of pigment enough to account for the image? Everyone now agrees that the remnant pigment is insufficient to account for the image. If you believe that informed skeptics think otherwise, you are beating what is now a straw man. But the fact that the image is not primarily due to pigment is irrelevant. If the original image was formed by rubbing with a dry or semisolid pigment, as Nickell proposes, and if the medium contained impurities which could oxidize the linen (many kinds of impurity would do, including some that would naturally occur in likely pigments), then when most of the pigment rubbed or flaked or was washed off over the course of time you would be left with an image primarily formed by oxidation as an unintended result, with traces of pigment _only_, but _invariably_, in the "image" areas, just as observed. [Chapter 13] It should be noted that a recent article (Biblical Archaeology Review, July/August 1986, p.18) by two pro-authenticity writers proposes a _naturalistic_ way that the oxidized image could have been formed. They think that this mechanism operated after the Crucifixion, but if their mechanism would work, so would Nickell's, since the physical mechanism of their proposal is not much different from his. > Remember, both McCrone and the original STURP team found crystals > of pigment materials. But the research team also observed the people > invariably *touched* things to the shroud. If a painter, having > completed a life-sized canvas, were to touch the painting to the > shroud, you would get the effect described. I do not think that this plausibly explains the facts that pigment was found on _nearly every_ sample from "image" areas, while simultaneously not a trace of pigment got on the non-image areas, even by accident. It also fails to explain why the darkness of the oxidised image is strongly correlated with the _amount_ of pigment found. To me this is not an explanation; it seems more like a way of "explaining away" unfavorable evidence. [Chapter 11] > The visible > image is still produced by the peculiar oxidation pattern, and it > still encodes the 3-d info that became visible on the NASA/Ames > image reconstruction equipment. No painting yet examined does that. I discussed the oxidation pattern above. The image reconstruction evidence is much weaker than pro-authenticity writers would lead one to believe. For one thing, the algorithm used made assumptions which practically guaranteed a 3-d result. It was iterated several times and the "mapping function" fiddled with until the results came out as desired. It therefore depends on circular reasoning. For another thing, the 3-d reconstruction (which I have seen) is not really very convincing. An expert on image reconstruction, Marvin Mueller, discusses this issue quite thoroughly in Nickell's book. [Chapter 8] > What about the actual presence of identifiable blood components, STURP was far from unanimous that the presence of blood was established. None of the STURP scientists who claimed to have detected blood (Pellicori, Heller and Adler) have experience in this field. Giorgio Frache, a forensic expert who studied the Shroud prior to STURP, was unable to detect the presence of blood despite using very sensitive tests. John F. Fischer, a practicing forensic analyst, discusses the "blood" tests in _Inquest_. The identification of bloodstains is his specialty, and he says that (1) the tests used by STURP scientists were faulty and not the best available (according to him, and contrary to what Heller says, the tests used by Frache were superior), and (2) the results in any case would _not_ be reportable in a court of law as blood since they could have had other causes. He also points out that the "blood" stains are the wrong color; they should be black (old blood is invariably black), and the stains on the Shroud are red. [Chapter 12] > and the lack of image oxidation, or visibility, below the blood? There is evidence that the agents used to paint the "blood" areas were different from those used to form the body image. If so, they may not have contained the required oxidizing agent. There is evidence that the "blood" painting may have been done with an egg or gelatinous tempera medium (residual collagen was detected in the "blood" areas). [Chapter 13] -- Glend. I can call spirits from the vasty deep. Hot. Why, so can I, or so can any man; But will they come when you do call for them? -- Henry IV Pt. I, III, i, 53 Bill Jefferys 8-% Astronomy Dept, University of Texas, Austin TX 78712 (USnail) {allegra,ihnp4}!{ut-sally,noao}!utastro!bill (UUCP) bill@astro.UTEXAS.EDU. (Internet)