Jones Beene wrote: > ----- Original Message ---- > From: Stephen A. Lawrence > >> If there's something more concrete, which pins the temperature and > the date a > little better, I'd love to see it. > > > Well, there was, but I am having trouble finding it now. Maybe you can help. > > I remember seeing an image in the days (maybe months) after 9/11 which > was some sort of remote sensing image from a satellite.
This would probably have been the evidence from NASA. However, remote sensing can't "see" high temperatures through an opaque mass of debris. At wavelengths emitted by very hot objects, which are in the visible band, it can only read the *surface* temperature. The (visible light) radiation from the surface depends entirely on the temperature of the surface. The surface temperature of any reasonably dark-colored (and reasonably hot) solid object can be determined easily just by looking at the color at which it's glowing. If the debris looked like it was at, say, 2,000 degrees when viewed from orbit, then people on the ground would have noticed that it was glowing yellow-hot. We wouldn't have needed a satellite photo to tell us that. Longer wavelengths, which penetrate the pile (and which are not visible to ordinary eyes and cameras on-site) can indicate the presence of significant heat. They can tell how fast the pile is leaking heat to the surroundings, which won't be obvious to people on the ground. But they can't tell you the exact temperature of the inside of the pile. A pile with a 3,000 degree hotspot buried under, say, 50 feet of concrete is going to look very similar to a pile with a hotspot of 300 degrees which is lying just under the surface. Consequently, AFAIK, it's impossible for the NASA remote sensing data to provide anything conclusive with regard to the presence or absence of melted steel deep within the pile. Another example of this effect is provided by the Sun. Its color is about right for something at a few thousand degrees Kelvin -- because that's the temperature of its *surface*. However, its core temperature is up in the multi-million degree range; we just can't see it, and we only "know" it's that hot inside because our stellar models tell us so. (If someone magically stripped away the photosphere and left the bare core we'd presumably all be incinerated ... and then we still wouldn't be able to measure the core temperature directly, come to think of it, since we'd be dead.) > > The details of this are foggy, and a quick googling has not located it - > but if I am not mistaken those thermal-images are color coded so that if > there was a pool of molten metal, then the image would probably give you > an accurate surface temperature of the pool as seen from space - and > from that, it should be possible to deduce the internal temperature > (under the slag which forms on the surface of molten metal) based on how > long it had been there. > > Hey - isn't this EXACTLY what our tax dollars were paying NIST to do ? > instead of a funky computer simulation. Actually, for most complex processes a computer simulation is the only way you'll ever unravel the details. That's why the government spends so much moolah on huge computers. See, just for laughs: https://computing.llnl.gov/?set=resources&page=index These monsters run simulations. That's *all* they do (well, except for crash, and run debugging tools to find out why they're crashing, and that kind of thing). What's more, the ones on the "OCF" list (Open Computing Facility) don't simulate anything that goes "bang". Rather, they're used simulating everything from weather to protein folding. If it's complicated, then the modern answer to understanding it is ... run a simulation. The ones on the "SCF" list (Secure Computing Facility) are used for more nefarious purposes, and if you look at the processor and node counts, some of them look like typographical errors. They're not. Things that go "bang" are very, very hard to simulate. (You may draw your own conclusions about what this suggests regarding the WTC simulations -- anybody know what kind of machine was used?)
