Metamars, you didn't answer this post:



But if it took a LOT of explosives, in each of three buildings, then SOME PHYSICAL signs of all these explosives going off should be OBVIOUS.

But NO EVIDENCE of explosives have been found.

How do you reconcile this discrepancy?

Arthur

What cavity sizes are you talking about? The concrete would've been crushed/pulverized during the break-up and collisions of the floors on the way down.

I recognize that my narrative style may not be aesthetically pleasing to someone who's looking to put equations on everything, but one of my own special interests is innumerability, how some situations simply don't lend themselves to numerical analysis. I'll match my narrative's accuracy to the accuracy of any mathematical model you attempt to cram the real events into. A realistic narrative is the basis of understanding, sometimes you can apply math to that foundation and crunch meaningful numbers, but the problem I've seen with the models to-date is that they've sought mathematical purity over realism and tend to ignore the phenomena that aren't described by their math.

I'm not looking to pick a fight over this, models have their place, but I'm just saying that a realistic narrative that provides insight into the various mechanisms of the collapse is worth at least as much as a differential equation that matches the time of collapse.

Solving for E1, for instance, doesn't provide insight into what it would've looked like when the ceiling collapsed. A lot of different things could result in a specific value of E1. If you want to understand the phenomenology of the collapse, you'll need more than values for terms to plug into differential equations.

Every model is based on assumptions, and if you start off with the wrong assumptions, the math isn't going to provide much insight however elegant it may be.

So, what sort of "cavity size" are you talking about, and what would that have to do with the concrete chunks getting pulverized by each other as they collide a thousand times on the way down?

As for the fuel-air munitions, the effect of an explosive on an object is pretty well understood (at least by me). I had the occasion to study effects of explosives in my first job out of engineering school, working for a company that perforates oil wells (among other things). It isn't that difficult a concept, if the overpressure on-set is slower than the speed of sound in the material, then the material will distribute the forces throughout its structure. If the overpressure-onset is greater than the speed of sound in the material, then the effects of the overpressure are localized to the blast region. (Please excuse the lack of differential equations in that explanation.) The difference between high explosives and low explosives is the speed at which they release their energy. High explosives go off faster than low explosives. Good luck trying to damage steel with gunpowder, or pulverizing concrete with a hyperbaric munition.

Regardless of whatever hyperbole some journalist has written about fuel-air bombs, the damage they generate isn't the sort that would pulverize concrete directly, but by creating a large enough volume of high pressure, they are capable of crushing a target. I suspect that when whoever said they're useful against bunkers, he meant that a hyperbaric warhead could be mated to a bunker-penetrator and detonated within the bunker to destroy it from the inside. Minefields aren't destroyed by blowing the mines apart, they're destroyed by triggering the mines, which generally have pressure-sensitive fuses. It's just an effective means of generating overpressure spread over a large area, so that's the mechanism that destroys the targets. Push hard enough on a wall, it'll fall over.

The mechanism of forces on materials is worth understanding, as it applies directly to your theory about energy getting coupled to the ground. As I pointed out earlier, many of the descriptions of witnesses withing the buildings said that they'd feel a jolt then hear a rumble and/or the building would start swaying under their feet, and I said that's exactly what happens in an earthquake - P-waves arrive first (which are sudden jolts) and S-waves (shaking/swaying) follow, and the difference between their arrival times is associated with how far away the epicenter of the quake was.

In this instance, the towers were stiffer in compression than they were transversely, so shocks went straight through the steel at 20,000fps, from the top down to the bedrock faster than a human could perceive, but transverse waves took longer to propagate through the building. The maximum amount of force that could be transmitted to the bedrock is determined by the strength of the structure, as when the structure is subjected to local stresses that exceed the structure's ultimate strength, that's when the structure fails and the excess energy goes into breaking and bending stuff right there, including concrete.

It's the same phenomenon associated with what happens to a material subjected to overpressure from an explosive, but in the material sense, the ultimate strength of the material is due to the spacing and strength of the molecular bonds in the material, where in the WTC towers, those bonds' strengths are determined by the structural design.