Chandler video transcript wrote:What we actually see here is the falling section of the building turning to dust before our eyes.
It would be generous to call that hyperbole. The upper section disintegrates or dissociates, yes, but by no means turns to dust. There is also a lot of dust. Is that a surprise? Not really. But keep the following in mind...A lot of what looks like dust in videos is not dust
Consider the scale of the structure and the distance involved in most videos. Anything smaller than about 10cm is indistinguishable visibly from dust in images. The means of distinguishing fine particulate from chunks is the former display diffusion mechanics in air and the latter display projectile mechanics. The former spreads and settles, the latter falls. There's a lot more visible
mass falling than diffusing and, implicitly but directly inferred, way more mass falling than what's visible.
Smoke rises, chunks fall, dust spreads. Does anything else spread or settle slowly? Anything with high surface area to mass. What were both towers packed with? Paper. Paper is seen settling everywhere post-collapse. From a mile away, paper looks like dust
. It gets entrained in air flow, disperses, and settles.
Clearly there's only a small fraction of the upper section converted to dust over the period in question, so the notion of a large portion the entire upper section turning to dust - let alone all of it - is false.Concrete is but a small portion of dust-producing materials
The big source is gypsum wallboard. Easily fragmented and crushed with a high proportion going to fine particulate. Plenty of other fragile materials. All of the easily crushed materials would begin producing large volumes of dust immediately in any collapse, and a relatively small amount of dust can expand into a large volume. Ceramic and other brittle materials crush more readily than concrete and will produce some proportion of dust.
Naturally, there was a huge amount of concrete and that will produce dust as it fractures, too. In demolitions where contents and non-structural members have been removed, there are still huge volumes of dust, generally of the order of the building volume or significantly greater. This is true even in verinage where no explosive is used. The classic case is the Balzac-Vitry but there are many others. Lots of dust, and very early on.Concrete was pulverized, but to a lesser extent early on
There was a final distribution of particle sizes in the rubble pile, but one should not infer the degree of pulverization was the same at all points and times during the collapse. This is not just a bad idea, it must necessarily be wrong according to thermal physics. There is more energy available to do work in pulverization in the latter stages of collapse, therefore there will
be more pulverization towards the end, period.
The greater kinetic energy of the rubble in the later stages, plus (and especially) the huge whomp of inelastic collision at the end when debris is basically brought to rest, must necessarily dissipate a huge portion of energy which originally came from the potential energy of the erect towers. That would be true explosives or otherwise (I'd be happy to elaborate on that if you wish but it's out of scope here).
Chandler's statement is at best hyperbole and at worst nonsense. You'd expect a large amount of dust, and there is. But he says the top 'dustifies' before our eyes. Not to my eyes it doesn't. I'd like to think what he really means to say is the top disintegrates but, if that's what he meant, he should have said it.