the 911research site contains a very interesting exposition claiming that the official explanation of the WTC collapse (cascading structural failure initiate by the effects of the post-impact fire) is little more than a clever ruse, but it does have it's own flaws...

I don't have the time to pull apart the entire deconstruction, but there's one really easy target:

From near the start of of the page:
>> The heating is probably accelerated by a loss of the protective >> thermal insulation of steel during the initial blast.
Blast? By implying that the impact fireballs were blasts, the authors confuse explosions, which produce very high pressures, with fireballs, which don't. A detonation wave can be generated by the sudden ignition of an unburned hydrocarbon-air mixture, but is not produced when ignition is continuous, as appeared to be the case with the dispersing fuel in the jet impacts. The fireballs took about 2 seconds to expand. Had they detonated, they would have appeared in milliseconds.

Blasts come in many forms. Normally the energy for a blast comes almost entirely from the energy of combustion. In this case, a good bit of the pressure came from the kinetic energy of ~10tons of fuel and assorted aircraft and body parts. Anything which generates enough pressure to push the fireball through a couple hundred feet of building, shatter thick high-rise wiindows and walls, and then another hundred or so feet out the other side would fit my definition of an explosion.

The point of the author of the original article was that one of the unexpected effects of the impact physics was that fuel and shredded airplane parts ripped off the insulation which had been designed to protect the floor trusses from the heat of a fire (which is, as the critic points out, normally quite tame in terms of mechanical force generated).

As for the wonder of the building collapsing at nearly free-fall speeds, consider that what you have is the top 30 floors of the building essentially impacting on the lower floors one at a time. (ok: 30 floors plus the number of previously demolished floors). This means that you have a roughly 30-1 or beter inertia ratio. Let's say tha the kinetic energy of the last 5 floors goes entirely into mechanical demolishing actions. This now leaves a 25-6 inertia ration. Let's round it off as 25-5, and and call it an even 5-1 ratio which increases as you have more mangled building joining the descent.

The fact that the building in a well-contained pile (well, OK: Except for the

"very fine dust being blown very energetically out to the sides as if the entire mass of concrete (about 400,000 cubic yards for the whole building) were being converted to dust." ) is explained by the somewhat unusual construction of the WTC.
Buildings prior to the WTC were generally build much like a human body.. a mostly squishy outside with a very strong central core (not unlike our backbone, but more symetrically centered). Had the WTC been built in this manner, the bottom few floors would have apparently consisted of more than 75% support structures for the upper floors -- leaing roughly no salable floor space.

To avoid this, the WTC was built more like a giant insect, with a hard crunchy outside leaving more room for a soft squishy (and entirely rentable) inside. As the WTC collapsed, those hard, crunchy walls helped to contain the collapsed bits for he first fraction of a section -- forcing them to go mostly straight down into the other floors (and thus accelerating the collapse). About the only things which could get much sideways momentum were paper and dust.

Although concrete holds up well under pressure, it has a relatively low tensile stringth. It tends to shatter rather than bend (as the steel beams did). The result of 30-90 floors worth of concrete and steel repeatedly impacting on the lower parts of the building would be easily enough to shatter most of the concrete in the building. Hitting the ground after a few hundred feet of near free-fall would be enough to shatter the upper portions.

This is not to say that alternate explanations are wrong, but the 'official' explanation isn't quit a full of, uhm, refuse as might seem at first sight. The mechanics of containment and the physics of the apparently near free-fall are independent of the cause.

Purple Crow wrote:
> From: Kai
>
> http://911research.wtc7.net/talks/towers <-- ASTOUNDING! Incredible
> data gathering that puts your favorite anchor-person to total shame.
> Just the facts, no conspiracy theory. A must read. (share) Suggestion:

.....
> Main page: http://911research.wtc7.net <-- The BEST link I have yet
> to witness on this subject!
....
> Love and Magick,
> Master`Reptoid.
> ~~~~]xxx[:>~
> http://PurpleCrow.ChaosMagic.com
>
> My key --> http://Geocities.com/Reptoid_27/PGPKey.html
>
> "An enigma wrapped in a riddle, with a tail in the middle."
> - Purple Crow
>
> "When protesters are classified as terrorists or terrorist
> sympathizers, when fear of federal retribution or criminal
> proceedings unprotected by Constitutional rights and
> safeguards force books to cease printing, websites to
> shutdown, voices to be silenced... we have a fascist state."
> - Polarization - The Plow Of Fascism - By James Neff - 6-1-3


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I did consider entitling this "The deconstruction of the deconstruction of the world trade tower destruction", but I thought .... Nah. That would be silly.