127.0.0.1 wrote:
> Dr. Keith Seffen's long-awaited "research paper", "Progressive Collapse of the World Trade Centre: a Simple Analysis", is available for review.
> The paper has been the subject of much conjecture, here and elsewhere, since it was cited by the BBC in an article published on September 11, 2007.
> According to the BBC, Dr. Seffen had constructed a "mathematical model" of the collapses of the towers. The article quoted Seffen as saying his research showed that once the collapse got started, it was destined to be "rapid and total" and that in "all senses, the collapse sequence was quite ordinary and natural."
> Strikingly, the BBC described Dr. Seffen's paper as "published", even though it had not been published at that time. A search of the publisher's archives found no mention of the paper, or its author, and after I pointed this out, the folks at the BBC changed their report, which now says Dr. Seffen's paper is "to be published". (Copies of the original text were preserved here and here).
> Articles published elsewhere propagated the error. And it turned out that the confusion stemmed from a press release put out by the University of Cambridge, where Dr. Seffen is a senior lecturer. The opening paragraph of the press release says that Dr. Seffen's paper is "published", but much later it says the paper is "to be published".
> On September 14th, I wrote a long and very critical article about the
> press release, in which I said:
> "I may be reading too much into this press release. The proof is in the
> pudding, as they say, and we won't know for sure whether Keith Seffen's
> paper contains any proof -- or anything approaching proof -- until we
> see it"
> ====
> Dr. Seffen assumes that a constant force, supplied by the suddenly unsupported top of the tower, was pressing down, crushing each story, one after another, all the way down to the ground. An elementary understanding of physics would tell you that this is not possible, unless the top section of the building -- the part doing the crushing -- were made of much denser material than the bottom section -- the material being crushed.
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No, the force even increases, being the sum of the total collapsing
material, and since it is not limited by air resistance, being an
internal air explusion, it can achieve near the speed of sound and
not just some speed limited by some modified terminal velocity.
> A single brick could crush a huge stack of paper cups and emerge intact. And this is the sort of situation Seffen's paper models. But that's not what happened to the World Trade Center.
> In the case of the WTC, the material being crushed was nearly identical to the material doing the crushing. In fact, the structural steel was thicker at the bottom than the top, in which light Seffen's model appears even less appropriate to the event (not that this makes very much difference in the long run).
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As I said, the mass collapsing continues to increase as it collapses.
> The point is: If the top of the building had crushed all the stories below it, then the damage to the top portion would have been significant: we would naturally expect that the amount of damage to the top would be similar to the amount of damage to the bottom. Or, thinking about the thickness of the steel, we might expect the damage to the top to be even greater than the damage to the bottom.
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You're completely misunderstanding all the physics behind the
non-conspiracy understanding of the 9/11 collapses. The model surely
involves the sum of the collapsing material at any instant, and does
so by consideringn the effect of one story on all the stories beneath
it, adding the stories above it which collapsed on it when the frame
bent.
> But in Dr. Seffen's model, the top section of the building is not destroyed in the process of crushing the stories below it; instead, its entire mass is still available to crush even the lowest stories.
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The MASS doesn't disappear if it itself is crushed!!!
> If post-collapse photos from Ground Zero had showed the top 20 or 30 stories of each tower, virtually intact and sitting on the ground, then Seffen's model could perhaps be considered appropriate. But according to all the video and photographic evidence, it's not even close.
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More nonsense, those hit the pile beneath at much more than any typical
terminal velocity, and the whole thing releases quite enough energy to
do the melting of aluminum seen in the wreckage, and the sub-red glow
of the iron.
Steve
