Preamble (in red font ): break with previous practice: I have taken the tail end off the very long posting that preceded this one, and am posting it here under a new title.
Why? Because the proposals for a STURP Mark 2 represent the culmination of some 30 months of study and research by this retired science bod. On re-reading, some of the ideas, especially as regards bringing the Museo Galileo into the picture, may seem somewhat tongue-in-cheek. Believe me, they are not. They are deadly serious.
Feedback is invited from IT and CGI-modelling specialists re the feasibility of my proposed "reverse-engineering' scan of the TS. That I see as an essential first step in verifying my belief that the negative TS image could and indeed probably was formed entirely by contact-only imprinting (the implications of which for authenticity we can discuss later)
From previous post:
Here's a comment (my bolding) from writer and historian Charles Freeman that has just appeared on Porter's vexatious site (from which I am taking a holiday/rest cure at present):
"Antikythera mechanism, apparently a hoax? No, simply look it up and you will see that it is genuine of its time and apparently a lone survivor of what must have once been several prototypes. Whenever anyone says that the Turin Shroud must be first century and genuine on the sole ground that it is unique and many aspects of it are apparently inexplicable, I just think of the mechanism!
The difference is that the Greek authorities allow access to bone fide scholars and as a result more is known about the mechanism every year as technology and x-rays develop more sophisticated ways of examining it. Not possible for the Shroud at present. We will learn a great deal more about it if it is ever given over to a laboratory for a proper investigation ."
That last sentence chimes with my call for a second STURP-style investigation
(see title of this posting).
But can it hope to tell us much more, even with more up-to-date technology, if restricted to non-destructive sampling, or those pussy-footing "sticky tape" samples? Maybe I'm being over-pessimistic, but at the same time I can think of certain crucial tests and analyses that need doing (details later) that would almost certainly be destructive, and where I for one would feel hugely inhibited from pressing for those and other destructive tests to be done if subsequent viewers of the TS were able to see the sampling sites and get uptight at the 'vandalism'. There is a solution to this, but it requires grasping a nettle.
It's time for a quid pro quo, or returning of a favour. Interest in the TS has been greatly increased by the application of modern science and photography since 1898, and while the radiocarbon dating has failed to support authenticity, the response of the 3 labs to the onslaught of criticism and abuse has been dignified (and I expect will remain so). I believe the time has come for the Shroud's custodians to do the decent thing, and make a gift to science. I'm sure they know what I mean, without me having to spell it out. OK, so it's 50% of the total but it's the less attractive 50%. Once definitive answers have been obtained, leaving most curiosity sated, what remains of that less than 50% could be displayed far from Turin, far from the prime 50%, say in an Italian science museum. There would then be twin centres for the TS - one restricted to occasional displays only, the other for permanent display. How about the Museo Galileo, in Florence?
|Museo Galileo, Florence|
First, I'll insert links to previous ideas I've posted, good, bad or indifferent, if only to demonstrate that there needs to be fresh thinking.
These ideas and approaches are for the most influenced (and limited) by this blogger's background in biomedical research. But none of them really address the central issue, namely that negative image, which as I have repeatedly stressed should be the main focus of Shroud research (not superficiality in my opinion, if the latter is then used as a peg on which to hang wacky ideas re mysterious collimated radiation). So now I have to doff a different cap, namely that of amateur physicist and rookie image analyst (more about the restricted sense in which I employ that term later),
Here's the gist of what I propose. Apologies if it's already been done (if so, please supply links).
Scan the TS image electronically, as one does when one takes a photocopy of a document. (I'll reveal my ignorance once more in asking whether the existing photoscans described as Durante 2002 and Shroud 2.0 were in fact digitized photography and/or 'photocopying', and thus capable of being described as electronic scans).
Sudden thought: up till now I have been using a digital camera to record my model scorches. Maybe I should scan the scorches instead, using the scan (or photocopy) mode on the ink jet printer. Might scan mode give even better 3D-rendering when uploaded to ImageJ?
Hot from the press: here's my first 3D-enhancement in ImageJ of scorch imprints from way back, using heated horse brasses as templates, that have been scanned (slowly!) on my Kodak ink jet printer instead of being photographed.
Click to enlarge
Better, worse, or as good as photographic images? Methinks the result is at least as good (and must presumably store a lot more digitized information that could otherwise be usefully processed. See my posting from Feb 2012 for a rough comparison.)
|Close up: same electronically-scanned scorch image from King GeorgeVI horse brass, before and after 3D enhancement in Image J|
Now comes the difficult bit. Use reverse-engineering, if one can so describe it, in order to create 3D models (on screen initially, 3D-printing would follow later) that make different assumptions, i.e. that there is contact with an applied 'envelope' (e.g. linen sheet) at all image locations OR that there is bridging of that envelope between points of highest relief (whether the latter be real or merely imputed) from the relief distribution OR that there MUST HAVE BEEN imaging across air gaps. One then looks at those 3D models and decides which of them in the real world could serve as a template from which the TS image was or could have been obtained by imprinting.
Here's my prediction: that the TS image could well have been obtained by a contact-only imprinting off a 3D subject/template. It's then of secondary importance whether it could have been obtained by assuming air gaps, since the latter is the soft option that requires exotic physics and a host of other qualifying assumptions.
Contact-only does NOT require exotic physics. If the modelling were to support a contact-only imprinting process, then my response to the arch-radiationists who glibly refer to cloth-body distances, or "air attenuation" of unspecified radiation etc etc etc would be immediate:
PUT UP OR SHUT UP!There's more I could say, quite a lot more, about the cynical self-serving deployment of agenda-driven pseudoscience that greets us, each time we open a newspaper or log onto an MSM web-forum.
(Late insertion: see today's Mail for an article exposing an individual with fake qualifications placing pseudoscience into the public domain in a campaign (increasingly successful) to block fracking for shale gas in the UK.)
The reason for this blogger/retired scientist to focus here yet again on the over-hyped Shroud of Turin with its authenticity-promoting circus is as follows. The dubious and in many cases false claims made for the Shroud are in principle testable - once the Shroud's custodians are persuaded of the need to give access to 'STURP team Mark 2', comprising real objective scientists with track records of success in scientific research.
PS: If you've time, please read the preceding blog, long though it may be, since it reviews the basis for this blogger's long-held doubts about the 'received wisdom' of so much we read from 'shroudologists', especially those who glibly refer to "cloth-body" distance, and would have us believe that air gaps, crossed by unspecified radiation., are obligatory for 3D enhancement (which they clearly aren't, as my horse brass experiments demonstrate). I've also been appalled at the way that the so-called 'ultra-superficiality' of the TS image has been seized upon to instantly dismiss contact-scorching as the imprinting mechanism, without so much as a single scorch being examined to measure its thickness. Indeed, the bandied around figure of 200nm as the TS image thickness is itself a guesstimate, based on failure to see the image in cross-section under a light microscope.
As for the claim that a scorch image can never be superficial, that it's bound to penetrate to the centre of fibre cores, this might be a good opportunity to introduce a new buzz word or term into the Shroud literature that's been incubating for a time, and was mentioned briefly yesterday. It's what I call 'ablative protection' as used to protect space craft from the heat of re-entry into the Earth's atmosphere . I believe it can explain why a sheet of dried onion scale leaf epidermis, just one cell thick was able to offer total protection to underlying linen while itself (the epidermis) becoming heavily scorched.
|Pencil sharpener used as hot template, pressed down onto dried onion epidermis with essentially no effect on linen underneath|
'Ablative protection', and its basis in thermochemistry (exothermic v endothermic chemical reactions) will be the subject of a future posting. Endothermic = heat abstracting.
1. Here's a brief scientific article that shows 3D visualization of 2D images. The images in question were mm thick slices from human cadavers!
2. Here's another paper (pdf format) that has developed algorithms for producing 3D visualizations of faces from 2D photographs.
So, the technology exists! Let's not forget our old friend ImageJ which provides 2D to 3D capability, but is it sufficiently adaptable to cope with different assumptions re cloth-body distance?
Speaking of which (ImageJ that is) what kind of 3D images of the ENTIRE TS image, frontal and dorsal, is obtainable, given tha radiationist's assumption that so many parts will be poorly imaged, given their assumption of cloth-body distances that must not exceed 3-4cm (the theoretical basis for which is poorly explained).
Here's one hot from the presses.
|Click to enlarge. Note the inferior 3D of the dorsal side (right) which has been frequently commented on, and which I recently to 'LUWU' as distinct from 'LOTTO' imprinting.|
Addendum Sunday Aug 3
One of the wackier aspects of the Mystifying Tendency in shroudology is the 3-4cm rule. Yes, we are soberly assured there is no imaging of the body when the presumed cloth-body distance exceeds 3-4 cm. How come you might ask? Why has Mother Nature thrown up this roadblock to imaging?
In fact, it's even more closely defined if you read the latest pdf instalment by Yannick ("why use just one word when ten will do ?") Clement to his endless and repetitive hagiography of the late Raymond N. Rogers of STURP. There we are told that the the cut-off is at 3.7cm (no, not 3.6cm or 3.8cm, but 3.7cm). There is no conceivable process in the natural world that can produce so abrupt a cut-off, and vague talk about "attenuation" effects, sometimes expanded to read "air attenuation of mysterious unspecified radiation, or diffusing molecules" takes us still deeper into the mire that is agenda-driven pseudoscience.
Do I have an explanation for the claimed 3.7cm cut-off that does not attempt to invent new physics, that has maybe a more mundane explanation. You bet I do.
I have recently proposed that the frontal image was obtained by a 'LOTTO' procedure (Linen On Top, Then Overlay), while the dorsal side was by 'LUWU' (Linen Underneath With Underlay). See link for explanatory diagrams.
The LOTTO configuration allows for manual moulding of linen to 3D contours of the uppermost frontal surface, achieving an arguably better imprint than the rear-side dorsal side that relies on generalized impaction pressure alone.
So which part of the hands are most likely to be used to ensure that linen is pressed down into the more important sunken relief and other hollows?
Might it be a bit more than a fingertip job, say an end-of-finger job using the part between the last-but-one joint and the tips?
I'll say a bit later about the anomalies regarding dorsal side imprinting, for which the magic figure is somewhat less than 3.7cm we are told. That too is explicable in terms of LUWU v LOTTO.
Afterthought: I consider that manual, finger-assisted moulding of cloth to template accounts for features of the TS that are not explained by application of a simple (simplistic?) 3.7cm rule.
There's probably not a great difference in elevation between the centre of the abdomen of a non-obese individual and the points marked with yellow circles. The better imaging of the central abdomen is explained by supposing that the manual moulding of cloth to contours did not extend into the angles where the abdomen abuts on the forearms.
Here's a 3D visualization of the same in ImageJ. I don't envy anyone the task of defending an imaging model that relied upon projection of a highly attenuated radiation across small air gaps, maximum dimension 3.7cm. The image density from eyeballing along that yellow line, say, (click image to enlarge) does not show the expected smooth rise and fall for imaging of a continuous variable across air gaps. It's more an either/or relationship - imaging when in contact, abrupt failure to imprint an image when not in contact. Manual moulding to contours with fingers (tamping down length/depth approx 3-4 cm) would seem to make a lot more sense.
Addendum: Sunday pm, Aug 3 (First draft: needs editing).
I've been doing some more thinking about scorches and their alleged non-superficiality. Even Dr.Paolo Di Lazzaro no less was at pains to make that point in a posting addressed to me individually, describing his ad hoc one-off experiment with a heated coin, the details (and defects of which) I'll return to later. Suffice it to say that his experiment confirmed all my misgivings about Paolo's limited scientific abilities (he is I believe an optical/ mechanical engineer by training and background, specializing in uv excimer laser applications and no doubt a very good one, but as I've said previously, I regard him as a Mickey Mouse scientist. In fact it was his cringe-making "uv excimer laser" nonsense that first alerted me to what was happening in the pseudo-scientific world of shroudology.)
The red arrows are apparently the sites of striations and discontinuities. (? see later)
AbstractThe pyrolysis characteristics of three main components (hemicellulose, cellulose and lignin) of biomass were investigated using, respectively, a thermogravimetric analyzer (TGA) with differential scanning calorimetry (DSC) detector and a pack bed. The releasing of main gas products from biomass pyrolysis in TGA was on-line measured using Fourier transform infrared (FTIR) spectroscopy. In thermal analysis, the pyrolysis of hemicellulose and cellulose occurred quickly, with the weight loss of hemicellulose mainly happened at 220–315 °C and that of cellulose at 315–400 °C. However, lignin was more difficult to decompose, as its weight loss happened in a wide temperature range (from 160 to 900 °C) and the generated solid residue was very high (∼40 wt.%). From the viewpoint of energy consumption in the course of pyrolysis, cellulose behaved differently from hemicellulose and lignin; the pyrolysis of the former was endothermic while that of the latter was exothermic. The main gas products from pyrolyzing the three components were similar, including CO2, CO, CH4 and some organics. The releasing behaviors of H2 and the total gas yield were measured using Micro-GC when pyrolyzing the three components in a packed bed. It was observed that hemicellulose had higher CO2 yield, cellulose generated higher CO yield, and lignin owned higher H2 and CH4 yield. A better understanding to the gas products releasing from biomass pyrolysis could be achieved based on this in-depth investigation on three main biomass components.
Based on the above information I proposed what I called a “fuse wire”explanation, in which exothermic pyrolysis, once started in hemicelluloses (HC) would continue until all the locally available HC was consumed, leaving unaffected HC in close proximity, assuming that the reaction, while self-sustaining due to exothermic nature, would be unable to jump gaps between one HC centre and another.
I now have grounds to refute my own mechanism, which are as follows. When a reaction is described as endo- or exothermic, as determined by the enthalpy change, ΔH, with the sign positive(+) and negative (-) respectively, there is an implicit understanding among chemical thermodynamicists that all reactants and products are in their normal physical states at ordinary environmental temperature, specifically 298 degrees K, i.e. 25 degrees C.
But here’s the pitfall for the unwary. A reaction that is exothermic under standard conditions, as reported for pyrolysis of HC, may not be when determined under non-standard conditions, as is the case when one presses hot metal into linen. Why not? Because pyrolysis reactions involve chemical dehydration of carbohydrates, which results in the formation of steam, i.e. gaseous water, H2O, and the physical state of that water is critical to the enthalpy change at standard v non-standard conditions. A pyrolysis reaction that is endothermic when water is produced as steam, resulting in loss of thermal energy from the open system, may be (in theory only) exothermic if the steam is unrealistically contained and allowed to condense back to liquid water at 15 degrees C, giving up the considerable heat of vaporisation of water.
In other words I strongly suspect that pyrolysis of hemicelluloses as well as cellulose is endothermic under realistic, real life non-standard conditions where steam and other hot gases are free to escape.
This has important implications for scorching, especially in context where a template is only just hot enough to produce a scorch on first contact. If the reaction is endothermic, then a second scorch will be considerably fainter (as I have repeatedly seen in practice). What’s more the first scorch may not be nearly as penetrating as one might expect. There is also an explanation for my onion epidermis result where a dried sheet of epidermal cells just one cell thick offered that sacrificial 'ablative' protection to underlying linen. (If two primary cell walls and desiccated cytoplasmic remnants can do it, then so might superficial parts of the linen fibre, e.g. primary cell wall, with some, not necessarily all the secondary cell wall too).
I have to decide whether to make a new posting of it (being quite long), which will then be seen as aggressive, or whether to add it on the end here, sotto voce, basically as unfinished business that had to be addressed sooner or later, or risking having folk think that I was stumped for answers, or silenced by the Voice of Physics. I'm minded to tack it on here, and then return to more realistic science than wacky kind being foisted on us and the media to make 'resurrection physics' seem respectable orthodox mainstream science. It ain't. It's pie in the sky.
Saturday August 9th
OK, I've decided to complete this posting with a point-by-point response to Paolo di Lazzaro, the latter speaking on behalf of the Shroud Science Group in response to a missive from Dan Porter, host of shroudstory.com.
I'm not entering into any further discussion with he, Porter or the SSG on this matter all of them having totally ignored my response to Di Lazzaro on that posting above).
If he does not accept my arguments, presented here after further reflection, then here's my suggestion: let Porter or someone else post Di Lazzaro's manifesto and my response to it to a neutral learned scientific society. Let it judge. I'm fairly confident that my science will prevail and Di Lazzaro's rejected. It was Di Lazzaro's so-called "science" announced with great fanfare in the UK media (December 2011) that first caught the attention of this retired science bod/science blogger, my having lost interest in the Shroud after the radiocarbon dating.
PDL's comments in the above posting are in black font, my replies are in blue.
Dear Dan and All:
I checked the idea of Colin Berry in the website you quoted. In short, from a physics point of view, his model is untenable, especially concerning the depth of coloration. Let me explain why.
Berry wrote: “The scorching will initially be confined to those parts of the fabric that are in immediate contact with the hot metal; no air gap is permissible, since radiated heat will not scorch white linen. What is more, the scorch will be confined to the outermost fibres of the thread, because the scorch will tend remain trapped within the first-encountered fibres, rather than being able to “jump across” to adjacent fibres. Why is that? It is because the resistant cellulose cores that are unaffected are able to conduct away heat rapidly, bringing the temperature of the hot template down to below that which will induce scorching Is it realistic to suppose that cellulose fibres could conduct away heat without themselves becoming degraded? Yes. I believe it is.”
It is quite easy showing the above assumption is wrong, and it is one of the few cases where it is faster doing the experiment than to explain the theory. According with a paper quoted by Berry, the onset of pyrolysis in hemicelluloses is at about 220°C. We have heated a 5-cents euro coin at about 230 °C in contact with a linen cloth.
Why is the coin heated “in contact with “ cloth. That is not how I did my model scorches, nor how a medieval forger would or could do it. One heats the coin first, and then removes it from the source of heat, such that it is cooling when it reaches the cloth, not becoming hotter as seems to be the case above. (One can also test the heated template with small swabs of fabric to ensure it’s at the optimum temperature for producing a superficial scorch, without measuring or knowing the precise temperature).
How did PDL manage to heat it while in contact with the cloth? Was there an electrical heating system, and if so why? Why choose a temperature higher than the one that produces pyrolysis (which I read anyway as rapid pyrolysis, chemical reactions never being all or nothing re a degree or two change in temperature). The combination of constant input of heat AND excessively high temperature is and was guaranteed to produce a scorch that is non-superficial, so the choice of title “heat cannot produce a superficial coloration” was wrong. The conditions chosen means the title should be altered to “heat can produce a non-superficial coloration”.
CONCLUSION: INAPPROPRIATE EXPERIMENTAL DESIGN.
Just 5 seconds after the coin reached the max temperature the whole cross section of threads in contact with the coin was colored.
All of which was thoroughly predictable.
Repeat: INAPPROPRIATE EXPERIMENTAL DESIGN.
After15 seconds all the thickness of the cloth was colored and the round shaped image of the coin appeared on the opposite side.
All of which was thoroughly predictable.
Repeat: INAPPROPRIATE EXPERIMENTAL DESIGN
After checking in our Lab, we repeated this easy and small-size experiments in the RAI3 TV studios (GeoScienza) to demonstrate that heating linen cannot give a superficial coloration. See http://www.tvrit.it/enea/20120103-RAI_3-COSE_DELLALTRO_GEO_1555-175825001a.ASF starting from the minute 16:30.
There is no point repeating experiments that are inappropriately designed. One will simply confirm the wrong answers, and then arrive at invalid conclusions like “heating linen cannot give a superficial coloration”. The aim should have been to produce the most superficial coloration, not the least superficial, using medieval technology, not misapplied modern technology.
After the experimental demonstration, let’s approach the basic elementary physics that explain why the idea of Berry is untenable, and heat cannot produce a superficial coloration.
“Let's approach the basic elementary physics”.
Yes, let’s, and hope it’s better than the practical operations.
The hot metal transfers energy (heat) to the primary cell wall (pcw) of the linen fibrils by contact.
Yes. Promising start.
From a microscopic view, transferring energy by contact means the hot (i.e. fastly moving) atoms of metal hit hemicelluloses molecules transferring momentum, thus increasing both amplitude and velocity of the motion of hemicellulose molecules around the equilibrium position (centroid). As a consequence, hemicellulose increases its temperature.
Yes, that’s basic kinetic molecular theory, what one learns at age 12 or 13. So where’s this leading?
In the regions of contact between pcw and cellulosic medulla, we still have a transfer of heat by contact, like in the previous metal-pcw case.
The medulla is a central cavity, so is not “cellulosic”. Indeed, it may not even be cellulose that is immediately adjacent, since the central cavity was originally the fluid-filled cell sap, with a film of living cytoplasm separating it from the cellulose of the secondary cell wall. It’s more likely to be remnants of cytoplasm, not cellulose that line the medullar cavity.
But yes, there is an interface between PCW and SCW (so references to the medulla are somewhat premature).
The temperature of the medulla will increase.
No, it’s the temperature of the SCW that will tend to increase. But we have forgotten something. The SCW will be protected by the thermal decomposition of the PCW, which while billed as exothermic under standard thermodynamic conditions (25 degrees C) is almost certainly endothermic when it’s an open system with no thermostatting , one in which hot steam can escape, abstracting heat and thus cooling the system.
In the region where there is no contact (e.g.,a small air gap between pcw and medulla) we have heat transfer by irradiation.
Heat transfer in principle, certainly, although I’m surprised that of the three main means of heat transfer, conduction, convection and radiation, the focus should suddenly be on the last of those three. Why? Because it’s what happens in practice that matters in a contact-scorch scenario, on a short-time scale . Unless dealing with incandescent bodies, radiation is not nearly as efficient a means of transferring heat as conduction or convection, both of which involve the momentum associated with atoms and molecules. Contrast with the energy of electromagnetic radiation which has no mass term. (E = hv). So let’s see where this line of argument is leading…
In fact, every material emits radiation having a spectrum peaked at a wavelength which depends on its temperature: the higher the temperature, the shorter the wavelength. This is the well known phenomenon of the black body emission, governed by Planck’s law, Wien’s law and so on (first year exam for students of Physics, Mathematics, Chemistry, Engineer).
So is this the public face the so-called Shroud Science Group (SSG) wishes to present to the world on the few occasions it appears outside its own forums? Claiming a superior knowledge of basic scientific principles, when so far everything from the over-hyped uv excimer project suggests an exceedingly weak grasp of those principles, specialist research degrees notwithstanding?
Note too the way the site’s host had trumpeted the intervention of an SSG member, using the opportunity to portray this researcher as Don Quixote tilting at a windmill. That was a blatant attempt to dismiss me and my science (mainly practical, with theoretical aspects taking a back seat) not bothering to hear my response. Does Dan Porter seriously imagine that science operates in that manner – by sending in the Marines to flush out opposition? What if those Marines are ill-equipped for their task, and have no knowledge of the terrain or what they are up against? PDL was clearly describing his first scorch experiment in an attempt to demolish my model, one designed to give his desired answer, and thus a total irrelevance (and worse) in scientific terms.
If that’s typical of the modus operandi of the so-called Shroud Science Group, then I for one am glad I never sought membership (and never will now, thanks to this – and another earlier* instance of what I consider shoddy treatment). Reminder: PDL was content with an in-and-out operation, failing to respond to my points.
* I was invited by Porter to give my reasons for rejecting Adler’s claims for “bilirubin” which I was told would be circulated among SSG. I did so, drawing on specialist knowledge re bilirubin acquired in Philadelphia working with 'yellow giant' J.Donald Ostrow in 1970-72 (much of it published). No response. Later I was challenged by another SSG member to defend my rejection of Adler’s techniques, which I did, in some detail, and again – silence. The SSG is frankly unwilling to address the details, content to let the Adler version go unchallenged, which Barrie M.Schwortz proselytizes on his lecture circuit, describing Adler a “blood expert” (he wasn’t) and that the permanently-red-blood/bilirubin narrative was for him the clincher (why, since Adler never proved its presence, despite claiming “extraordinary levels". In fact Adler never even proved the presence in Shroud “blood” of human protoporphyrin IX, despite being recruited initially as a porphyrin specialist.).
Back to the specifics:
I do know about the emission spectrum from hot bodies. I also know that you have to get metal filaments etc incandescent before they radiate enough heat to scorch neighbouring materials, especially light reflective ones like linen. That’s why my very first posting on this site used thermal radiation from an incandescent light bulb AND charcoal on linen, the latter being obligatory in order to intercept and absorb enough radiation.
|My first posting on this site, December 2011: inspired, nay provoked by Paolo Di Lazzaro's craw-sticking brand of Roman Catholicized theophysics.|
It was designed to flag up the “forgotten factor”in your photochemistry, namely the First Law (there has to be nett absorption of radiation before there can be chemical reaction, nett being the difference between incident and re-radiated energy). If the incident radiation is reflected or scattered, and there is little absorption, then there is little opportunity for sufficient energy of activation to produce chemical reaction.
|Thermostencilled image using charcoal to sensitize fabric to infrared radiation. No charcoal: no scorching|
This was also the kind of stuff one learned (at school in fact, doing London University Advanced -Level Chemistry AND Physics) before going on to University to do Biochemistry up to and including PhD).
As an example, at 20 °C the walls of a room emit radiation with a broad spectrum, peaked in the far infrared at about 10-micrometers wavelength.
Yes. One can take pictures in the dark, using the emitted infra-red radiation. This is common knowledge, and needs no specialist science education.
In the case of hemicelluloses at 200 °C the pcw emits infrared radiation peaked at 6,1 micrometers.
That makes sense. The temperature is higher, so the peak intensity shifts to a shorter, i.e. more energetic wavelength. But where is this argument leading?
In the case we are considering, the 6-micrometer wavelength will interact with the cellulose of the core of the linen fibril (medulla), exciting vibrational levels of cellulose that decay in heat thus increasing the temperature of the medulla.
Ah, so we have finally arrived at the central proposition, namely that infrared radiation emitted from the most superficial part of the linen fibre, i.e. the primary cell wall, will radiate energy to deeper locations, the SCW, and proceed to heat them up.
But how efficiently, given that the chief means of heat transfer will be conduction, and given that infrared radiation is inefficiently absorbed by light coloured substances?
There is an entire branch of radiation physics devoted to the subject of blackbody radiators. We learn of the theoretical idea of the perfect blackbody radiator, which not only radiates infrared efficiently, but absorbs it too. If one’s going to invoke infrared radiation as a means of heat transfer, one has to consider the nature of the radiating/emitting surface, which is critical to how fast, or slow, it can operate vis-à-vis alternative means of heat transfer.
One cannot assume that a phenomenon that works in principle, given sufficient time for thermal equilibrium to become established between radiating and absorbing bodies, works in practice too, when the system under study is that of brief contact scorching. Short time scales render heat transfer by radiation exchange irrelevant, unless dealing with dark or black materials. We are not. Excluding the small amount of lignin in linen fibres, we are dealing with colourless or white hemicelluloses and cellulose that tend to reflect rather than absorb incident radiation, infrared as well as light.
In addition, a well known optics law tells us the penetration depth of the interaction between radiation and medulla cannot be smaller than the wavelength, that is, not smaller than 6 micrometers in this case. This fact alone explain why infrared radiation cannot produce a superficial coloration of fibers.
I don’t pretend to understand the first sentence. But I don’t need to, since the second is irrelevant. I have not claimed that infrared radiation can produce a superficial coloration of fibres. In fact, my model largely discounts radiation effects, due to absence of opaque pigments. My model says it’s conducted heat that produces discoloration. Whether it’s superficial or not depends on how the superficiality is measured. The author omits here (and elsewhere) to say how superficiality is measured, despite scores of references to that term. Why make such a big play of superficiality, or the frequent references to “200nm” when the latter was simply a guesstimate on the part of Raymond Rogers? The author has no sound basis in science to declare model contact scorches generally as being non-superficial if he has not bothered to measure them, and has chosen experimental conditions that virtually guarantee that his model scorch will be too penetrating through a combination of excessive temperature AND excessive application time.
By the way, it is not possible that “the resistant cellulose cores that are unaffected are able to conduct away heat rapidly” (see above Berry’s statement) because of elementary fluid dynamic equations (a classical engineering problem), of a not convenient area/volume ratio of cylinders (elementary geometry) and because Berry assumes a exothermic pyrolysis of cellulose, that is,by definition, a runaway process, extended in time.
The first part means nothing to me, knowing as I do nothing about fluid dynamics. But I do know about starch, cellulose and other polysaccharides that contain extensive inter- and intra-hydrogen bonding, and know that in principle that applied heat can causing ‘melting’ of crystalline or semi-crystalline regions, followed by recrystallization either to original configuration, or retrogradation to something different with new crystallinity. So one cannot resort to classical physics that assumes constant chemical character when there are in fact reversible or semi-reversible heat cycles that can play a role in the buffering as well as propagation of heat energy along fibres, the latter surviving largely intact (see the ‘boil water in a paper bag’ trick for a striking demonstration).
As for the last words, I have been seriously misquoted. I did not say cellulose pyrolysis was exothermic. I quoted the Yang paper that stated that it was hemicellullose pyrolysis that was exothermic; cellulose pyrolysis was stated to be endothermic, and to suggest it could be otherwise would display an ignorance of its great chemical stability, which is why this researcher (the first person in science to characterize resistant starch as retrograded linear short-chain amylose) greatly resents that misattribution.
In summary, when heating a linen cloth by a hot metal in contact, well known physics models foresee the pyrolysis of the whole fibers and threads, and this is exactly what we observe in the experiments.
Well known physics models cannot possible foresee pyrolysis. Pyrolysis is a chemical change, outside the remit of physics. All that is being “foreseen” is unimpaired heat conduction that might result in pyrolysis at distal locations, but as I have suggested, there may be abstraction of conducted heat, either via permanent chemical change (localized pyrolysis) or reversible chemical change (“buffering”) due to reversible cycles of melting and recrystallization in the bulk cellulose.
Useless to say, it is all the approach of Colin Berry to find a middle age technology able to create the Shroud image that is hopeless: just consider the half tone effect. It could not have been made by medieval forgers because they would need a modern microscope to observe and then control their micrometric-scale coloration.
This statement is amazing, betraying as it does a huge misunderstanding regarding macroscopic v microscopic change, between spontaneous order v disorder process in the natural world, between entropy change at the level of localized “closed” systems and entropy change in open ones. And yes, chemists and biochemists need to understand these things, merging as they do with fundamental physics, and they are an important part of our training.
The quickest way to deal with it is to provide an analogy: snow making machines.
Nett result: macroscopic simplicity to microscopic complexity, and all from removing (not adding) thermal energy from H2O.
The take-away message, in case you have not already guessed it, will be simple: macroscopic simplicity, i.e. merely switching on an energy-abstracting heat pump, can result in microscopic diversity and complexity, none of it requiring human intervention. Molecules, even simple ones like water, H2O have an inherent tendency to self organize through "stickiness", once their kinetic energy is reduced by cooling. The possibilities for re-organization produced by input of thermal energy ("heating") are substantially greater.
PDL's thinking is rooted in thermodynamics, concerned purely about the tendency of spontaneous change from one state to another, indifferent to time scales, indifferent to whether or not there's an easy and practical route without too high an energy of activation. But brief contact scorching is not just about thermodynamics. It's about kinetics too, and while both thermodynamics and kinetics are favourable for scorching of linen immediately in contact with hot template, they may be unfavourable to scorching away from the immediate zone of contact. Invoking "radiation" does not help one's case, if the radiation is mainly reflected, rather than absorbed.
All the best
Update Monday 13 October
It would seem as if my proposals for reverse-engineering (well, something like it anyway) have been assiduously worked on elsewhere, by none other than the respected Joe Accetta of STURP, judging by this abstract of the paper he has very recently delivered at the St.Louis Shroud conference.
Note the final words: "... under any reasonable assumption about the surface bi-directional reflectance distribution function (BRDF) including the use of measured human skin data, the observed 3D properties cannot be reconciled with any known radiative imaging process and thus must be a contact process."
There's a wiki entry on the BRDF technique, which frankly this blogger with his limited maths and physics did not find terribly helpful (like what can one do with it??). Hopefully the YouTube tutorial will help, despite its length (almost an hour long!).
I'll report back here when I know some more, both as regards the Accetta presentation and hopefully its reception. As for understanding how BRDF works, we'll have to wait and see...
PS: I see that the above abstract was in fact posted some time ago on shroudstory.com