9-11, give me a break.

[abaris]

It's entirely possible, and in my layman's opinion highly likely, that it was caused otherwise -- namely, the failure of steel girders which had had their fire protection stripped by the impact and subsequently exposed to continuous high heat. That same heat likely melted the aluminum from the airplanes. The heat generated by the fires can both have brought down the buildings and, in that process, melted the aluminum.

Three factors, far as I remember. Heat, structural weakness, weight. But I'm not doing the homework for idiots like the above. They can very well move their own asses to look up expert opinions on the buildings collapsing. Which they won't do. So it would be wasted energy anyway.