...explains very well the difference between the WTC towers and the Empire State Building.

The ESB is essentially a tower of concrete. It's massive and the floors would not collapse on each other because they are resting on concrete and steel pillars.

The WTC OTOH was a light framework of steel. Once the joists broke, the floors had nowhere to go but down.

Hate me all you like, but these are facts.

...doesn't mean it will be dark. Nerdnam is correct that the Empire State building tells us little about the WTC, because the construction was very different. One can't draw many parallels. However, the method of construction is a highly technical direction, difficult to argue, that nerdnam keeps trying to obfuscate, even though he doesn't understand it. He draws the discussion away from other evidence which destroys the official story much more transparently (pools of red-hot molten metal, remember?).

I did followed his link first time he posted it, and found it an unimpressive little piece of unsupported speculation, some of it patently false. For instance it implies there are no safety margins in modern computer aided design, which Nerdnam obviously dutifully inferred. I'm sorry, that's nonsense. CAD allows much more accurate measurement of your safety margins, but no engineer ever leaves them out.

However, following this line of argument is really pointless (why oh why am I still feeding the trolls?)... Strength of construction would not be required to slow down the falling. Just by being stationary when hit, whack whack whack, the floors would have slowed the fall down more than observed.

Those of us who don't believe, should probably not put so much effort into persuading the nerdnams of this world (so I should shut up, right?). The official story is an article of faith to him, and as Rumsfeld et al are being led from the dock in chains he may still say it was the planes.

I think anyone reading this thread, with any level of scientific education, will have already have been able to decide who has logic on their side, and I think most people will already have left. With any luck they'll leave via sites like http://www.scholarsfor911truth.org.

quote:

Just by being stationary when hit, whack whack whack, the floors would have slowed the fall down more than observed.

end quote.

Not so. If the first floor couldn't bear the weight of the 14 or 20 floors above falling on it, then the second floor below could even less bear the weight of now 15 or 21 floors falling on it. The next floor below would have been struck with the weight of 16 to 22 floors.

Each floor would have been hit with an accelerating and ever increasing mass and thus would have offered less and less resistance to the falling mass. Very quickly, the resistance of the floors would have become meaningless to the speed of the fall. Like I said, it would be like a bullet going through a leaf or a bowling ball on top of a straw. Therefore there would have been little difference from free fall.

I'm driving to work soon and will probably smack into a few mosquitoes along the way. Will the speed of my car be affected? Not in any way that can be measured by science. And similarly to WTC collapse: a half million falling tons is not likely to be impeded in its path by mere bolts in the wall, particularly when each floor was only designed to hold its own weight.

As far as the fire chief, anyone can visit or observe the EMB and compare it to modern buildings. Modern high rises are in fact much lighter and while they are very economical to build, in the case of the WTC there was a price to pay for that economy.

If you think the discussion is too technical, consider this:

If you buy cheap bookshelves, the shelves will be secured on the ends by pins in holes. The shelves should hold a normal set of books, but if you put more weight than expected on the shelves, the pins are likely to give way. If the shelf above happens to fall on the shelf below, this will be even more weight than expected on that shelf, and your whole structure is likely to pancake and collapse.

However if you build your own shelves, you proably set the shelves on upright boards every 30 inches or so. This makes the shelves very srong and even if one shelf were to collapse, all the other sitting on columns are likely to hold. This is how the Empire State Building was constructed as compared to the WTC.

The shelves (floors) in the WTC were simply held by pins (bolts) in the wall, just like cheap book shelves. Is this clear enough for everyone?

Thus when the floors fell, there was nothing below the floors to impede their collapse and they fell near the speed of free fall.

I'm neutral: open-minded, unconvinced either way at this point, but with a definite healthy skepticism of "official" government explanations for anything... particularly anything emanating from the current US administration. I thought, this being Salon, that we'd have an interesting, informative and reasoned letters page response to Patrick Smith's article.

Well, it certainly has been "interesting". Informative in parts, as well.

As for reason, as far as the structural analysis of the towers' collapse goes, I think nerdnam makes his point well and convincingly, and without accidentally spelling his/her opponents names in ways that happen to be derogatory. Calling him/her a troll is also weak, given the largely factual nature of his/her contributions, and is a far better example of an ad hominem rhetorical attack than anything nerdnam has written in this fascinating discussion. Certainly on an emotional level, the conspiracy theorists here come across more like the creationists described.

That said, I would have liked to see the molten metal tackled. Molten metal, note, not molten steel, which is an important and surely relevant distinction.

But the glaring aspect of the "freefall" argument that nobody here has even hinted at is this: I too was beginning to be swayed by the idea that the towers fell too fast considering the resistance of the floors. Ignoring the difficulties of performing an accurate time measurement, however, there is one perfectly visual piece of evidence everyone here is ignoring. Namely, that parts of the tower did fall faster than others, that the plume or mushroom cloud of debris ejected outwards and down from the point where the upper floors collapsed onto the lower ones did indeed fall faster than the rest of the buildings! Therefore, unless they fell faster than freefall (!), the rest of the building simply had to have fallen slower than freefall. This is just simple inescapable logic, and requires no training in or understanding of structural engineering. Can anyone tackle this -- and why everyone including the anti-conspiracy theorists are ignoring it -- without name-calling? Maybe I'm missing something, and if so I'd love to be put right on this point.

I have another couple of ideas and questions I'd love to discuss (particularly around the order of collapse relative to the order of the attacks), but I'll see if anyone responds to this (in the spirit of discovery and without rancour, if possible) before going further.