Reverence for 9/11

I am not familiar with the term "pancake theory". What I am sure about is that if a few floors fell on the one below, the weight alone would be enough to collapse the floor because it would be many times its specified load. 15 times was the approximate figure in the article I linked, but the floors moving at several meters per second would obviously be far more damaging. Engineers building a structure whose weight is critical do not overspecify by 15 times.

Wait a minute?  So were the explosives installed before the planes hit the buildings or after?

I think shoddy workmanship is a much more plausible answer than a governmental conspiracy.  C'mon, trysts, there are plenty of actually despicable acts attributable to the U.S. government.  We needn't start believing "fairy-tales".

The towers were not specified to survive the aftermath of the impact of a heavily fueled passenger jet (they were strong enough to survive the impact, but clearly evacuation was critically compromised by the damage done).  They were built light and strong enough to stand a hurricane, and very specifically were meant to be able to stand 3 hours of an an out of control fire with the sprinkler system inoperative. On those grounds you might call the construction shoddy, but the aircraft fuel appears to be the reason the buildings did not survive this long.

I would believe that upon each floor collapsing on another, that it would slow down the collapse. This did not happen. I would believe that the fuel from the plane mostly burned away shortly after impact, and therefore the fuel would not remain hot enough to compromise the steal. I would believe the building collapsing would not perfectly collapse into it's base from such high buildings. But if such good luck did occur, it would be impossible to happen three times in a few hours.

The narrative leading up to that event, and the subsequent legislation, wars, and propaganda afterwards is highly indicative of the event being ordered by this government. It is probably best not to call those investigating that event crazy. It neither helps your case as a thoughtful onlooker, nor does it look like anything more than suspiciously narrow.

The explosives would have to be set some days or weeks preceeding the event.

It is because of governmental crimes, which lead me to question the government. 9/11 is an excellent case, therein.

Yes, they were. The designer said that when taking into account a plane hitting the towers, they were not only built to withstand one plane impact, but many planes impacting. And he did say, 'why would he design the buildings that way without taking account the fuel in the planes?'

I think you are misunderstanding what was said - please provide a reliable reference.

The buildings were structurally able to withstand the impact of a heavily fueled plane, and they did so. However, a major design failing was that the impact made the upper floors impossible to evacuate. They were also specified to survive 3 hours of a fire without collapsing and they did not do so. My understanding is that this was because of the additional source of fuel for the fire.

How would it make any sense to have specified the buildings to to survive longer in a fire started by the impact of an aircraft than another fire??

The sidebar on the right of this article gives a very detailed description of the way the collapse was caused (you can skip down to the heading "the collapse of the towers").

http://911research.wtc7.net/wtc/analysis/design.html

There's often a disconnect between design engineers and builders.

Yes, it appears that John Skilling was wrong in his judgement. Not entirely unheard of for engineers to fail to anticipate disasters, unfortunately. An important factor that had not been adequately taken into account is that the impact did a lot of damage to the fire insulation around the central column, allowing it to be damaged more quickly by the fire. Also, it appears that the weakening of the perimeter columns by fire may have been inadequately accounted for.

Anyone who believes the buildings were brought down by explosives, rather than  by the damage done by the collision of aircraft and the ensuing fire has to explain why a collapse would start at the floor a plane had hit. I assert this is as clear a "smoking gun" as you are ever going to get (as if the cause of the collapse wasn't blindingly obvious to anyone who realised that planes do not crash into skyscrapers often enough to make it merely a co-incidence).

Your belief is implicitly based on an incorrect assumption about the relationship between the amount of kinetic energy gained by several floors falling one floor and the amount of energy needed to cause a floor to fail. It could be true in a different structure that was relatively much stronger.

If the top floor was dropped and there were no floors beneath it would reach a speed of 90 m/s when it hit the ground. In reality it is reported that by the time the collapse reached the ground, it was moving at around 60 m/s. This means that, very roughly, half the kinetic energy of the collapse was absorbed in the failure of the structure. This is a lot of energy - presumably because the central column (and to a lesser extent the perimeter structure) absorbed a lot of energy as it was destroyed.

This indicates an accelerating collapse, not at 9.81 m/s, but at a reduced acceleration due to the resistance of the remaining floors of the building. This acceleration would also have varied throughout the fall, as the mass and speed changed, but was clearly always positive and always less than 9.81 m/s.

Looking at this as a physics problem draws home to me what a terrible human disaster it was. One extraordinary fact I was reminded of today was that 20 people were extracted alive from the towers after the collapse. But so, so many were not. I'm still remembering them.

It does not appear that way.

The explosives could have been set throughout the entire building. We do not know what kind of explosives were set, or how it was controlled. We do know that the crime scene was blocked from independant investigation, quickly cleaned up and sent to China.

trysts, the collapses started where the planes hit, just after the towers had started tilting slightly due to the weakened structure.  I quote from the referenced wikipedia article on the collapse itself:

"In both cases, the portion of the building that had been damaged by the airplanes failed, which allowed the section above the airplane impacts to fall onto the undamaged structure below."

You can imagine any other mechanisms you like, but you need an explanation of why the floors where the planes hit failed. This seems patently absurd.

If something is yellow, quacks like a duck, lays eggs, has webbed feet, lives in a pond, has a bill and has the genetic code of a duck, my conclusion is that it is a duck.

I'm not good at equations in physics. Here, this person appears to verify my eyes:

"My conclusion is that the fall of the towers is inconsistent with the pancake model. The floors beneath the point of initial collapse must have given way prior to the arrival of the top floors, i.e. by explosive demolition. Understand that I haven't attempted to include resistance of the steel in the towers to the collapse which would have further retarded the progress of the fall. With that in place a fall of 20 or more seconds is not unreasonable. 11 seconds is definitely unreasonable."

The equations that may be of interest to you are contained within one short page. They contradict what you're assuming. Here they are:

http://ebtx.com/wtc/wtcfall.htm

Why did WTC 7 fall down? Even the guy who leased the place said it was pulled(demolished).

Well, if he leased it, he must have been right. 

My understanding is that WTC7 caught fire (inarguable), that the sprinkler system was virtually inoperative due to the effects of the previous events on the water supply, the fire services were not in a position to fight the fire, and the fire was sufficient to cause it to collapse. I recall being greatly surprised as well. I read that WTC7 was damaged by falling rubble from one of the twin towers, but this was not a crucial factor in its own collapse.

A positive point is that, as far as I know, there were no casualties in WTC7.

Especially when he was asked at the time, if he should "pull it". Especially when he had recently aquired those buildings and would get paid more money from the insurance company if the WTC "plaza" was attacked by terrorists. Larry Silverstein is worth a thorough investigation.

Thank you. This link is interesting, and was pretty much what I was too lazy to do in detail earlier. It made me aware of a sloppy statement of mine. My claim that roughly half the kinetic energy was absorbed is incorrect - it was actually much less than half.

I agree with the point that the fall appears to have been surprisingly fast, but cannot draw the same conclusion. What sense is there in the theory that explosives were placed in the building and detonated only during the collapse started on the floor hit by a plane?? This is as ludicrous as claiming the US government were in league with Al Qaeda in a co-ordinated attack on the WTC.

"What sense is there in the theory that explosives were placed in the building and detonated only during the collapse started on the floor hit by a plane??"

There isn't any.  It's an absurd notion.

The simplest reason is usually the rightest.  The building, likely, wasn't built to engineering specifications.  Obviously, if it weren't, there would be no documentation to say so.

Thanks, bigpoison for a voice of calm sanity.