Marshall Dudley, James Osbourne-Holmes wrote: "Because it is not so. See "General College Chemistry" 6th edition, page 96 and 97: Absorption spectrum: When continuous electromagintic radiation, for example, white light, passes thorugh as substance, certain wavelengths of radiation may be absorbed. The wavelength are characteristic of the substance that absorbs the radiation, and the pattern of these dark lines is referred ot as the absorption spectrum. When cool a substance absorbs radiation at the same wavelengths that it emits when excited. Marshall "James Osbourne, Holmes" wrote: "As for so-called "Far infrared fibres" - the concept defies basic thermodynamics. All materials emit and absorb precisely the same spectrum of heat radiation when at the same temperature." If this is so, why do infrared thermometers have an "emissivity" adjustment that varies with the material being scanned? A black body has maximum emissivity.Other materials vary depending on their composition and surface texture."
Solar Wrote: "Kevin, The ability of a material to absorb energy at one wavelength and emit it at another is very easy to demonstrate. It is done on a daily basis. Something as simple as a flourescent light works like this. The ultraviolet light emitted by the excited gas is converted to white light by the phospher coating. One can also use a nitrogen laser emitting UV to excite various dyes, which then emit energy at another wavelength. Believe it or not, human bone behaves in this manner. When excited by ultraviolet light, it emits IR radiation. This is covered in the book "The Body Electric", by Dr. Becker. Because I am rearrnaging my entire house right now, I can't cite the pages, or the studies, at this time. As long as the energy conversion doesn't exceed 100%, I can't see where it violates the laws of thermodynamics. I do understand your statements, though, concerning two bodies, at the same temperature, without additional energy being added. In that case, yes, they will emit energy at the same wavelength.-- Best regards, Solar" Folks - apples are being compared to oranges. I was at pains to point out that we are talking about a product "FIR fibre", that supposedly bathes the object in oodles of far infrared when applied at room or body temperature (or in the case of meat wrapped in a FIR bag, in the fridge). Under these circumstances, the fibres are at or very close to the temperature of the surrounding environment. They are not being bathed in sunlight, UV, lasers, or the like. I repeat - any material in thermal equilibrium with it's environment emits and absorbs precisely the same spectrum as the environment - there is no possible enhancement of far infrared waves. See for example "Thermal Physics - 2nd Ed'n, Charles Kittel/Herbert Kroemer, pp96-97: Emission and Absorption: Kirchoff law". We notice objects around us having different colours and shades precisely because the light by which we are able to see is very far from being in thermal equilibrium with our room temp environment - the effective temperature of sunlight is around 6000 degrees centigrade. Emissivity and absorptivity is then very important - black underwear dries on the clothes-line much faster than white underwear, etc. The point here is that a knowledge of basic physics can save one being conned. As stated before, the FIR material worn as underwear, socks, etc, can only "work" if it happens to have better insulating properties than brand X - but that is a separate issue to what we are discussing here. regards, Kevin Nolan [email protected]
