Recall TWA 800, the 747 that exploded and split in two after it took off from New York? This case was full of conspiracy theories, remember the rocket launched from a Navy ship took it down. They found evidence of explosives during the initial investigation and the FBI at that point was certain it was a terrorist event, however their own investigator didn't believe it. Turns out that the plane was used for training some time prior to the crash, where some explosive substance was hidden so the bomb squad could train their dog. The real cause was a spark that ignited fuel vapors in the tank under the wing. It also happened on a 737 in Asia, only that plane was still on the ground.

The World Trade Center had been a terrorist target for a long time. The first almost successful attempt to take it down was in 1993, when a vehicle packed with explosives blew up. They were close, but not close enough to hitting the right part of the structure. Finally, they were successful in 2001, by flying planes into the building, as well as the Pentagon.

What happened to the World Trade Center is well documented. It was a terrorist attack. Focusing on some aspect of the event and putting forth a theory in the face of overwhelming evidence to the contrary is to me indicative of a closed mind.

Myself, I think it is a good thing to read and listen to points of view that don't agree with your own, but in this case, you might as well be watching daffy duck and just enjoy the entertainment.