I would like to know why it is more believable that these explosive, focused blasts of pulverized material coming out at the mid-points of the building are more easily explained by these two quite ridiculous explanations, which i will argue against in advance, than the squib theory, which they perfectly resemble.
1. The first is given by popular mechanics:
"Like all office buildings, the WTC towers contained a huge volume of air. As they pancaked, all that air — along with the concrete and other debris pulverized by the force of the collapse — was ejected with enormous energy. "When you have a significant portion of a floor collapsing, it's going to shoot air and concrete dust out the window," NIST lead investigator Shyam Sunder tells PM. Those clouds of dust may create the impression of a controlled demolition, Sunder adds, "but it is the floor pancaking that leads to that perception." "
Alright pancake people... We are talking about 20 to 30 floors below the collapse front. These floors are completely intact, so there is no reason why the crushing floors 200 feet above should exert a pressure that great on the floors that far below. No reason. I think we can all agree that this argument is a big load of crap.
No. The argument is not "
a big load of crap". That argument is one from incredulity. Dynamic pressure travelling down various HVAC and other sorts of mechanical shafts, stairwells, and other cavities within the building perfectly well explain this observation. No explosives necessary.
2. The progressive collapse pressure wave theory.
Some people have professed that a pressure wave travelled down the tower, somehow ahead of the collapse front, that blew out air from windows 30 floors below.
Again, dynamic pressure. Why wouldn't it travel that far?
There are so many holes in this theory, and i will address a few:
A. How does this pressure wave travel through the building in such a way that is powerful enough to blast out windows?
R.Mackey gave some important information to understand before you get the answer to that question:
Windows require approximately 1 PSI of pressure to break. This can be either static or dynamic pressure. For dynamic pressure, this equates to a fluid velocity of about 100 meters per second...
You understand that when a moving volume of a fluid, whether a liquid like water or a gas like air, gets forced into a smaller volume, either the pressure will increase, or the mass will move faster. This is the principle behind what happens when you put a finger or thumb over the end of a garden hose: The water moves faster. Now, imagine the air contained on one of the floors of the Twin Towers being moved by the mass of all the floors above it. Some of it will shoot up through whatever gaps exist in the rubble, some of it will shoot out, and some of it will shoot down through whatever shafts/gaps/opening are available, whether they're elevator or HVAC shafts, stairwells, gaps between walls opening up to gaps in the floor structures... whatever. The point is that the air gets moving into those small spaces.
Since there's only a limited number of areas these places can open up into, once air moves through multiple shafts/gaps/openings onto another floor - whether the floor immediately below where it started, or many floors below - it follows whatever path it can as the mass above continues to fall. It's being "pushed" out and around. At some point, some of the air is not only going to be moving quite fast, but it's going to hit a window. If the mass is moving fast enough, then it will blow out the window. If it's not, it won't. The fact that window blowouts are not consistently seen on each floor in predictable spots actually argues against the notion of explosives being used - they'd be distributed a lot more evenly and would not be creating such a random blowout effect, whereas the complex and chaotic flow of air around the various paths naturally lead to some windows experiencing enough dynamic pressure to blow out, and others not.
At any rate, this would not only be why it travelled so far down - the path travelled would depend on the open spaces available to it - but why there were not consistent blowouts in a predictable pattern.
B. This theory has not been scientifically proven. There is no evidence that this wave can even occur given the structure of the building and the behavior of the collapse. I find it very difficult to believe that this piledriving action of the top section was able to increase the air pressure in one floor 20-30 floors to the point of blowing out windows on multiple sides of the building when there are numerous shafts and resevoirs for this air pressure to be contained.
And those "shafts and reservoirs" would have to open up somewhere. If you're talking about HVAC system ducts and shafts, there would be multiple openings per room, let alone per floor.
Instead of arguing from incredulity, consider the fact that you're talking about acre-wide floors and tons of debris falling that used to be the upper 10- or 20-some floors, depending on which tower. It's hard to see how there wasn't a large amount of air moving wherever it could. And keep in mind that each floor was not hermetically sealed. "Numerous shafts and reservoirs" is almost the right way to think about things, but not if you propose that the air will flow into those areas and not flow out; again, very few of these "shafts and reservoirs" would be hermetically sealed on the end the pressure is moving towards. It wouldn't be like a syringe plunger pushing against a perfectly sealed tube at all, it would be pushing against spaces that had multiple openings. When a moving air mass reaches a given floor, the air has to go somewhere. Some of it escapes out the side, some of it continues to travel down through whatever path it can find. The fact that some of it doesn't find an escape until many floors below the collapse front is simply not unexpected. Ultimately, we're talking about a large volume of air being pushed by a huge mass. There's nothing unusual or counterintuitive about any of the noted effects.
C. Even if there was enough pressure from this wave to travel through the elevator shafts and out the windows of the building, it doesn't explain the pulverized building material. How was concrete able to be pulverized. You can see the enormous amount of dust and debris that gets blown out of the window along with the window itself.
Much of the "pulverized" building material was fairly lightweight stuff, like ceiling tiles, cubicle dividers, drywall etc. My goodness... how much drywall alone is there in any given office? I don't know what the exact amounts are, but I don't see how a lot of the dust cloud was concrete to begin with, given the sheer amount of all that other material. To claim that the dynamic pressure couldn't have pulverized the concrete, you must first demonstrate that a significant amount of the dust
was concrete to begin with, then you must demonstrate why pneumatic effects were responsible, instead of other effects, such as the sheer amount of energy involved in all that weight separating from its supports and falling.
You are merely presuming that the dust cloud is concrete. If you're going to presume anything, then it's far more reasonable and logical to presume the interior office contents were the major components, since by your own description, you're talking about stuff blowing "... out of the window...". That would be drywall, ceiling tiles, office materials like paper, particleboard from furniture, etc.