The evidence for mid-air pulverization can be seen here:
It has been pointed out that it is uncommon of a demolition to collapse from top to bottom. While this is true, it can be done and I myself have seen it done in a non 9/11 context (I saw a video of such a demolition somewhere).
It has been argued that each floor underwent sudden impact of thousands of tons with a momentum that could not be stopped by what the tower was designed for.
I have challenged the author of this argument (KennyJC) to know who his source for this information is. I have pointed out that even NIST doesn't actually account for the collapse of the building, a glaring ommission. Steven Jones explains:
The NIST team fairly admits that their report “does not actually include the structural behavior of the tower after the conditions for collapse initiation were reached.” (NIST, 2005, p. 80, fn. 1; emphasis added.) Quite a confession, since much of the external evidence for explosive demolition typically comes after collapse initiation, as seen in cases of acknowledged controlled demolition. (Harris, 2000.)
The rapid fall of the Towers and WTC7 has been analyzed by several engineers/scientists (http://911research.wtc7.net/wtc/anal...fs/speed.html; Griffin, 2004, chapter 2). The roof of WTC 7 (students and I are observing the southwest corner) falls to earth in less than 6.6 seconds, while an object dropped from the roof would hit the ground in 6.0 seconds. This follows from t = (2H/g)1/2. Likewise, the Towers fall very rapidly to the ground, with the upper part falling nearly as rapidly as ejected debris which provide free-fall references (http://911research.wtc7.net/wtc/anal...fs/speed.html; Griffin, 2004, chapter 2). Where is the delay that must be expected due to conservation of momentum — one of the foundational Laws of Physics? That is, as upper-falling floors strike lower floors — and intact steel support columns — the fall must be significantly impeded by the impacted mass. If the central support columns remained standing, then the effective resistive mass would be less, but this is not the case — somehow the enormous support columns failed/disintegrated along with the falling floor pans.
How do the upper floors fall so quickly, then, and still conserve momentum in the collapsing buildings? The contradiction is ignored by FEMA, NIST and 9-11 Commission reports where conservation of momentum and the fall times were not analyzed. The paradox is easily resolved by the explosive demolition hypothesis, whereby explosives quickly remove lower-floor material including steel support columns and allow near free-fall-speed collapses (Harris, 2000).
And these explosives also readily account for the turning of the falling Towers to fine dust as the collapse ensues. Rather than a piling up with shattering of concrete as we might expect from non-explosive-caused progressive collapse (”official theory”), we find that most of the Towers material (concrete, carpet, steel, etc.) is converted to flour-like powder WHILE the buildings are falling. The Towers’ collapses are not typical implosions, but quite possibly [a] series of “shock-and-awe” explosions — at least the evidence points strongly in this direction. The hypothesis ought to be explored further.
In post 32, KennyJC argued that just because most of what you saw was dust, does not mean that everything that is falling is dust. I agree, there were certainly some steel girders being ejected out. But in terms of the concrete, it was mostly pulverized, as 9/11 research makes clear.