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Inside the debate

September 1, 2006

Skeptics claims -- and the scientific responses:

Allegation: Steel skyscrapers do not collapse from fire. Explosive charges were secretly set in the buildings before 9/11 and detonated after the planes hit.
Rebuttal: The kind of explosives needed to collapse the Twin Towers would have weighed thousands of pounds each and required forklifts to move around. They could not have been secretly hidden in the buildings.

Allegation: The Twin Towers came down at free-fall speeds, which would not have been possible unless the base of the buildings was blown up by explosives.

Rebuttal: The North Tower came down in 12 seconds at 125 mph. Free-fall speeds would have brought it down in eight seconds at 186 mph.

Allegation: WTC 7 was not hit by any plane and fell seven hours after the attack. It was brought down by explosives in the building. The tower's owner, Larry Silverstein, told PBS in 2002 he made the decision to "pull it," slang to blow it up.
Rebuttal: WTC 7 remains among the most contentious events of 9/11. Engineers now believe the unusual design of the 47-story building over an electrical substation and the tanks of fuel stored inside made the fire burn hot and long enough to wreck support columns. A final government report on WTC 7 is due this year.

Allegation: That Air Force fighter jets did not intercept the hijacked planes, even after one crashed into the WTC, is proof the military let the attacks happen.
Rebuttal: The 9/11 hijackers turned off their planes' transponders, making them very difficult to track. Also, the military had almost no experience or readiness to intercept planes flying over the United States.