wow, this is the stupidest thing ive ever heard. you all are getting too paranoid. the trade centers could in fact stand up to a plane hitting them and they could even have withstood the high heat. what they couldnt stand was both at the same time. what happened was the steel infastructure was deigned so that the steel rods in the floor were what held up the building. they were coated with a flame retardant material. when the plane hit the debris knocked off some off the flame retardant material expoing the metal and causing them to warp. it looks like a professional demolition job because thats what happened. one floor colapsed onto another which collapsed under the impact of the first floor and so on and so on.