At the risk of widespread abuse, the only thing I did hear which I haven't seen explained is that it has been suggested that the twin towers should never have collapsed after the initial impact as even despite the fire and soaring temperatures, there were reinforcements in place which should have kept the building standing....
Anyone seen that one blown out the water?
(I'd like to add I'm a sheep, and never believe conspiracy theories on anything. I like mainstream, and I'm sticking to it!)
Some very interesting (if you like engineering) reading on why the towers collapsed here:
http://www.tms.org/pubs/journals/jom/0112/eagar/eagar-0112.htmlEssentially, the temperature of the fire in the towers was nowhere near hot enough to melt the steel.
Most engineers agree that the first thing to give way were the joists on the most heavily burning floors, this caused the outer box columns to bow slightly and caused all floors above the fire to drop.
The upper floors dropped onto the floors below them, the joists of these lower floors were held onto the core structure by metal angle clips, which weren't strong enough to support the weight of the floors above them. This caused a domino effect where each floor couldn't alone support the weight of those above it, and collapsed onto the one below.
