Perhaps the answer lies in the Monty Python sketch in which a building is maintained by hypnosis.
The problem with conspiracies is the obvious contradiction with real world government competence. Take a good look at Iraq or the intellectual depth of Bush and reason accordingly. I don't see any reason why conspirators should haul Sacks of thermite and ignite them in synchrony with ( extremely reliable) suicide bombers - when explosives would do a better job. More than that, I doubt the WTC buildings were as well built as the Empire State building - when it survived A collision with a WWII vintage bomber.
