"I am not an expert in demolition, but I understand that there are several techniques that could be used to bring down buildings. At least in the case of the 3rd tower, there are many documented reports of explosions.
There guys seem to have serious doubts also:
http://www.ae911truth.org/ "
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Well, Bernard, one could say the plot thickens by the day.
Whether 'explosion' sounds were due to explosives or simply to physical failures of materials isn't shown; in either case, if there were explosives involved, then by whom were they placed? Would internal Tower Security people not have been able to see them being planted, either by terrorists or by the darker arm of government? Were they planned as early as during the actual construction, wouldn't the builders have twigged what was going down?
Perhaps witnesses simply do not know what they hear, which in that context, wouldn't be at all surprising. As stun grenades are used to gain access to building in the hope of disorientating armed thugs, the effect on the public must be fairly similar when present in the scale that the Towers represented. I was in one car crash - I hope the last - many years ago, in in my mind it was all in very slo-mo; the reality? Who the hell knows, least of all myself!
Rob