"Squibs"
Conspiracy theories are often built around anomalies which are difficult to prove either way. The "assumptionists" are convinced they know what the anomaly is. One such anomaly is the so called "Squibs".
They say this anomaly is an explosive charge going off and a sure sign of Controlled Demolition. It's often followed by more video of charges going off in real Controlled Demolitions. But if we examine the anomaly closely, we see these [would be] explosives work in reverse to an explosive blast. They tend to spurt out and then increase with time. An explosive works in reverse to this. Its strongest point is the moment the charge is set off. It doesn't increase its explosive strength with time.
So what is this then? Why would debris jet out of windows far below the collapse?
It could be a number of things, by themselves or in combination. One reasonable explanation is a buildup of pressure caused by the compression of air between the floors as they pancaked, (Please read the link to explain the NIST / Pancaking issue) pushed debris out of the already broken windows and/or open vents. Another is falling debris like elevators or elevator parts/motors and/or columns free falling down the elevator shafts and slamming into lower floors creating debris. In a sense the floors are large plungers and the towers are just one big Syringe during the collapse.
During the pancake, the floors acted like a plunger in a Syringe. The towers skin and windows became the tube of the Syringe. The increased pressure blew the windows out as each massive acre of floor compressed air between them. It's said that the towers were about 95% air. But not all the air went so easily out the window space. There was just as much window as there was steel perimeter columns. So the air takes the path of least resistance to the core. The core is collapsing and thick debris is preventing the air from going up. Its next path of least resistance would be to go down the core. The air pushed though the core any way it could and the pressure built up. It forced its way out on lower floors wherever it could. According to the survivors of at least one tower, a hurricane wind blows through the staircase which is located in the core...
Matt Komorowski: “The first thing I really felt was the incredible rush of air at my back. And maybe I felt it before everybody else, because I was the last guy.”
Stone Phillips: “Like a gust of wind, behind you.”
Matt Komorowski: “Gust of wind. Wind tunnel. It was the most incredible push at your back, that you can feel.”
http://www.acfd.com/miracle_of_ladder_company_6.htm
BILL BUTLER, NEW YORK FIRE DEPARTMENT: We took two steps down from the fourth floor and the building started to shake.
SALVATORE D'AGOSTINO, NEW YORK FIRE DEPARTMENT: You could hear the floors pancaking one on top of the other, huge explosions.
LIM: Boom, boom, boom, boom, boom, and faster as they get closer. What I remember the most was the wind. It created almost like a hurricane-type force and actually pushed one of the firemen right by me.
MIKE MELDRUM, NEW YORK FIRE DEPARTMENT: I was flown down a flight of stairs, a little groggy for a while. I noticed somebody on a half landing just up from me, a few stairs and I thought it was one of our guys and it was David Lim.
CNN.com - Transcripts
Of course, I expect the conspiracy theorists to say this was just the explosives which caused the high wind ("He even says explosions!") but they have no evidence of explosives. We do have evidence of pancaking. The ejecta coming out of the windows of the pancaking floor was uniform across the floor and light in color. It was coming out of every floor window until the falling debris obscured its view. Controlled demolition has staggered ejecta because the charges are only on some columns. You also always see at least [some] before the collapse and not [only] during it. There are none of these jets of debris before collapse.
Another point is the amount of these so called squibs. Some are laughably small wisps of smoke. I wonÂ’t even bother with these. These are people who are searching every video, frame by frame in order to find something which they can use. Some are simply glass falling and reflecting sunlight or a piece of aluminum cladding doing the same. Yet, some seem to be heavy jets out of a window on one floor and another jet of debris about 30 to 40 stories below as the collapse progresses. I have to admit, when I first saw this I didn't know what to make of it. But as I thought of the possibilities, I also thought of what it needed to be if it were a demolition. In all the controlled demolitions I've seen, there have been a large amount of explosives on almost all floors. Even some small buildings have many charges. Why would they put charges on what seems like only a couple of floors? And once the collapse progressed, why would they care about the 40th floor? When the top 70 floors are crashing down on the 40th floor; even conspiracy theorists have trouble believing that floor would stop the collapse. And even if it did, the message is sent. The towers were no longer usable after the top 70 stories fell on it. It would be an added and absurd risk to add explosives on the lower floors.
The best explanation which fits the evidence is that there were heavy objects free falling down the elevator shafts and hitting the lowest landings. The explosive force of one of these...
...hitting the elevator, then lower floors would be tremendous. Hitting an elevator below would only add to the weight and explosive effect. It would send debris away from the impact point with great force. It's not unreasonable to suspect these heavy objects obliterated the fireproofed gypsum on the way down. Couple that with the over pressure of the collapse and you have a good candidate for what we see. Is that the only thing it could be? Not at all. I, like the conspiracy theorists, don't have an inventory of every window that was broken and every piece of equipment which could have created the effect.
So, we are left with jets of debris which do not act like explosives, on not enough floors to have caused the collapse. We also have some likely explanations which do not involve explosives.
Debunking 9/11 Conspiracy Theories and Controlled Demolition - Squibs