Reply #40: It is a bit disheartening...

[Carefulplease]

It is a bit disheartening that when some posters actually provide references and arguments in support of their claims, they are accused of being obfuscators.

The discussion of a 5 second variance in a collapse time that is variously estimated to have lasted 9 to 16 seconds certainly is an issue -- unless, that is, we are to stick to naive intuitions and dismiss any quantitative arguments grounded on actual measurements and the laws of physics. Much smaller variances in one tower's rate of fall could be accounted for by a variations of more than an order of magnitude in the resistive force. See Frank P. Greening's paper that I've referenced earlier.

The duration of the collapse isn't the sole issue, of course. I've addressed it in message #15 and I've also addressed the issue of dust expulsion in message #29 and the issue of mechanical resistance from the structure below in message #25.