Originally Posted by MediaGuy

There's plenty of questions as to what happened.

Considering the effectiveness of steel girder heat dispersion, how did trusses 50 stories below the crash site and any fires experience such loss of tensile strength - considering that it would take temperatures several hundred degrees higher than the fire was at its hottest to even begin to soften the metal?

And supposing somehow heat reached that far from burning jet fuel, how did it propagate evenly to all trusses on every level so that the building could come down straight, smoothly, and without any resistance, in a few seconds, without any toppling?

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