At this time of the year it is always good to check the state of the 911 conspiracy theory. It seems that many people have got into the impression that most of the demolition arguments have been debunked. Is this so? I will briefly investigate the technical arguments that I have earlier considered the strongest.
I found that F. R. Greening has written an article
„The Pulverization of Concrete in WTC 1 During the Collapse Events of 9-11” available at
http://www.911myths.com/WTCONC1.pdf
where he tries to debunk the claim that a gravitation collapse could not pulverize the concrete.
The WTC1 collapse started at the 95th floor. Above this floor were 15 floors. Greening calculates that the the mass of the upper floors had the kinetic energy of 2.1 gigajoules when it fell on the 95th floor. The floor contained 627 tons of concrete and 900 tons of structural steel. Greening comes to the following conclusion: For one floor
The elastic strain energy of the steel required 51 MJ
The elastic strain energy of the concrete required 34 MJ
The plastic strain energy of the steel required 284 MJ
The plastic strain energy of the concrete required 234 MJ
Together these yield 603 MJ
The plastic strain energy of the steel causes buckling of columns, the plastic strain energy of concrete causes pulverization of concrete. Elastic strain energy is the energy stored by the structure that can be released if the external pressure is removed: the material returns to its original shape.
For a drop of each floor the 15 upper floors lose 2.1 GJ of potential energy. 0.6 GJ of this energy is needed for breaking the structures, thus 1.5 GJ is converted to kinetic energy. It is 71.4%. The kinetic energy mv2/2=m(at)2/2=ma2(2s/a)/2=mas where s is the distance of the fall and a is the acceleration, assuming the acceleration is constant. The potential energy is mgh. If 0.714 of the potential energy is converted to kinetic energy, then a=0.714g=7 m/s2.
WTC1 was the North tower. One analysis of the collapse time is in the link
http://911research.wtc7.net/wtc/analysis/collapses/freefall.html
The height of a floor was 3.7 m and the whole building collapsed. We can initially take s=95*3.7 m=351.5 m. The time for the collapse is t=√(2s/a). Inserting s=315.5 m and a=7 m/s2 yields t=10 s. The first glance of empty space where the North tower stood is after about 13 s from the start of the collapse from video, but the reason is that 60 stores of the naked core of WTC1 remained standing up for a few seconds before they also collapsed.
David Chandler’s analysis of the initial part of the collapse of the North tower give the acceleration 6.31 m/s2.
The measured points fit very well to the assumption of constant acceleration and the result is that the acceleration a is 64% of the acceleration of gravitation before the building disappears to the dust. F. R. Greening’s calculation gave a bit higher acceleration, 7 m/s2, but he made estimations of dissipated energy. Furthermore, there are two issues changing the acceleration: on each floor the mass of the floor increases the falling mass but on the other hand lower floors are stronger. We cannot get a precise value for acceleration from Greening’s study. Thus, Chandler’s figure for the acceleration can be taken as a correct measured value: breaking the structures of one floor takes 34% of the initial kinetic energy of 2.1 GJ. That is 714 MJ.
As Chandler’s measured value for the acceleration is about the same, an in fact a bit smaller, than Greening’s, we can conclude that the North tower does not fall too fast. The collapse can be caused by gravitation alone.
We get the first result: The acceleration of the North tower is not in free-fall speed and can be explained by a gravitational collapse.
Chandler continues his argument: as the upper floors break the lower floors, the lower floors break the upper floors. This argument has a caveat. Each broken floor adds to the falling mass: each floor dropping 3.7 m adds 1/15th of the initial kinetic energy, 140 MJ. This means that 5.1 broken floors have enough kinetic energy to break the floor below it. The floors above six broken floors will not be destroyed by the reaction of the lower floors as the mass of the 6 broken floors destroys the highest lower floor. Thus, we may assume that 6 floors of the initial 15 floors above the impact can indeed be destroyed by the reaction force, but not the 9 remaining. Chandler\s piston theory: that the piston would be itself destroyed, is not so obvious. Over half of the piston could remains. The piston could by itself destroy the floors below it, but this is not necessary as the mass of the broken floors does it.
A better argument is to focus on the outer walls. In the video we see the outer walls. Will floors remain connected to these walls? What could happen is that the weight of upper floors hits the highest floor of the lower part. Steel columns buckle and are thrown aside by elastic energy these columns have absorbed. The upper floors continue downwards and at the same time break outer walls simply by their kinetic energy. But this is not the official theory. At least in one version of the official theory connections of the floors to the supporting pillars get broken. If this is the case, then the floors pancake down on their own and outer walls are destroyed by outer walls of the upper floors, not by the mass of broken floors.
The upper floors and broken floors fall down and the kinetic energy that can easily break the lower floors. The concrete of one floor requires 268 MJ of energy according to Greenings calculations and possibly a bit more to account for Chandler’s measurement that breaking concrete and steel takes 34% of the potential energy. But Greenings figure is not much off. Thus, the floors can gain 2.1+0.14-0.268 GJ=1.972 GJ assuming that they do not need to break any steel structures while falling. This is 94% of potential energy in the initial stage. Therefore the floors can fall with 94% of the acceleration of gravitation and the collapse continues through the whole building: the floors can indeed pancake to the ground.
Assuming that floors pancake like this and the connection of the floors to outer walls is broken, what happens to the outer walls? If they stay more or less intact and standing, they can only be broken by the steel structures of the upper floors. The additional mass of a broken floor will not fall on the outer walls of the lower floors: it will fall on the sides and mostly inside the building. If the outer walls of the lower floors are still standing up when the floors have pancaked, then it does look like the outer walls of the lower floors break the outer walls of the upper floors. The kinetic energy of the upper floors decreases as the upper floors fall down and outer walls of the upper floors break and fall on sides. The collapse of outer walls would stop in this scenario.
But is it necessarily so? It may be that when the floors fall and pancake, the outer walls of the lower floors are not standing straight any more. When they are hit by unbroken walls of the upper floors, the piston, which still has floors attacked to walls, these outer walls of the lower floors could bend and buckle with much less power than it takes to break walls that still stand straight up. I find this scenario very improbable as the outer walls were supporting structures. They most probably were able to stand in a stable way without the floors. If so, then if upper outer walls break outer walls of the lower part, the outer walls of the upper part must also get broken.
The second result: it is not necessarily true that the lower floors break the upper floors and the collapse stops, but if we accept the official theory that the floors got unattached from outer walls and pancaked, then it seems very likely that many floors of the outer walls should have stayed up. What happened was that the naked core stayed for some seconds and then collapsed. That does not fit to the official theory very well.
It is very easy to understand why the official theory must claim that the floors got detached from the outer walls. In the video we can see puffs many floors below the destruction level. There are only two possible explanations for these puffs. One is that they come from explosions and the other is that they are created by pancaking floors. As the official theory denies explosions, they have to claim that the floors pancaked several levels before the outer walls, i.e., the floors broke loose from outer walls. Then they have the obvious problem: why the outer walls collapsed all the way to the ground level. They do not have an answer to this question.
I mentioned that there could be a possibility that the external walls of the lower part could be weakened by the falling floors and stated that it is improbable. Fortunately we can remove this possibility by looking at the video. The video shows air puffs indicating where the floors had fallen, assuming that explosives were not used. We also see that the walls between these air puffs and the destruction zone have not fallen, thus pancaking floors did not weaken the external walls of the lower part at least much. We also see that the upper floors do get disintegrated, so it is not a piston that can break the external walls of the lower part and not be broken itself. The only conclusion is that when the upper floors have disintegrated and the floors have fallen down, the external walls of the lower part should be standing. Chander’s second argument turns out to be strong: WTC1 could not collapse without explosives.
The third result it that heavy steel beams thrown vertically do not necessarily prove that there was external energy. This is so because steel bends and absorbs energy. Then this energy is released. This release of energy may be the reason why heavy steel beams are thrown vertically as seen in videos.
It is seem that the arguments for controlled demolition that I so far mentioned are not absolutely certain, though they suggest a controlled demolition. There are stronger arguments demonstrating that the collapse used external energy.
I think the strongest argument is the high temperatures and testimonies of molten steel long time after the event. Aerial thermal photographs show relatively high temperatures after one week and some hot spots still after two weeks. Office fires should burn down in one-three days and the jet fuel burned down in seconds. There should not be left anything that could burn after a week. Also unused explosives and thermite would burn fast, if it is going to burn. The most natural explanation in my opinion is that there were very hot pockets covered with concrete rubble. As concrete is a poor thermal conductor, these pockets stayed very hot for a long time because they were extremely hot to start with. This is why they could convect through concrete and radiate to the space, which explains the hot spots in thermal images. I know no other explanation for this phenomenon. The explanation is supported by photos of molten steel and eyewitness descriptions of molten steel pools.
The second strong argument is the collapse of WTC7. David Chandler’s calculation of the acceleration of the collapse of WTC7
gives the free-fall speed for 8 floors. That is not possible for gravitational collapse. Wilton Paes de Almeida Building in Sao Paolo fell with the speed 6 m/s2 as calculated by metabunk experts
The acceleration was similar to the acceleration of WTC1, which is to be expected in a gravitational collapse caused by fire. We can conclude from this that WTC7 did not collapse due to fire. Yet, it is not admitted that the building was pulled. This is a very good reason to suspect that the collapses of WTC1 and WTC2 did not happen as told.
We can calculate what the acceleration for WTC7 would have been if the collapse was due to fire. The acceleration is higher if the falling mass is larger as there is more kinetic energy and the portion of energy that is spent on breaking structures is smaller (naturally, the acceleration stays below 9.81 m/s2). Thus, let us assume that 47 floors fall. Let us also assume that WTC7 was rather similar to WTC1 and Greening’s estimations are suitable. Greening got 2.1 GJ kinetic energy for 15 floors falling one floor level, so 140 MJ for one floor. For 47 floors it is 6.58 GJ. The energy for breaking structures was 0.603 GJ. Thus, for 47 floors 0.603/6.58=0.0916 part of the kinetic energy is needed for breaking structures. The acceleration is then 0.908 times 9.81 i.e., 8.91 m/s2. Chander measured 9.8, not 8.9, so WTC7 did not fall by gravitation.
A very strong argument is the dust of WTC, which contains iron spheres and possibly unignated nanothermite. About iron speres we can be sure. They can only be created in very high temperatures, which cannot be reached by jet fuel and office fires even if escalator vents could have provided air and the fires were much larger than they looked. The problem with this argument is that it is difficult to prove that the dust is WTC dust. Still, it is very likely to be WTC dust.
There are other good argument, like that WTC1 tilted to one side but then straightened up. It should not happen in gravitation. The building in Sao Paolo also tilted to one side, but it did not straighten: debris fell on that side.
Additionally, pre-knowledge that some people had of the terror strike, points strongly to who did it. But we know who was behind the strike just by looking at the cover-up. There definitely has been a cover-up in 911 and mass media has taken an active part in it. There is only one party, which can control the media in the USA and the world.
I do not think there is any need for a deeper look in the proofs of controlled demolition in 911. None of the strong arguments have been debunked. It is only a propaganda game played by the mass media, debunkers and trolls. Some specific arguments, such as that a gravitational collapse cannot pulverize concrete as in WTC1, can be shown incorrect, as was done by Greening. Yet, taking all arguments together, they make a very strong case for a controlled demolition, even though the nature of explosives is not well-known.
Debunkers of 911 like to take a weak argument and show it incorrect and then to suggest that it is all false. This approach is dishonest. What is the difference between Holocaust revisionism, where revisionists also take one argument and show it incorrect, but I do not consider it dishonest? The difference is that in the Holocaust case what is shown impossible is a witness statement. A witness claims to have seen something. If he could not have seen it, then his statement is invalid and that it enough. In the 911 case the debunkers attack a theory, not something that anybody claims to be necessarily true. Theories of controlled demolition may be correct or incorrect in details, but debunking some individual arguments does not invalidate the theory of controlled demolition. Showing witness statements invalid does invalidate most of the proof there is for Holocaust. That is a major difference. Well, the controlled demolition theory still stands.