This is an explosion…

There are no intact floors above the advancing collapse line. The concrete and debris are immediately pulverized and ejected sideways along with other parts of the structure including heavy beams that go on to destroy neighboring buildings.

There is no ‘pile-driver’ effect as is evidenced by this photo and further confirmed by the arrested angular momentum of the upper floors in the south tower.

The collapse proceeds through the strongest part of the building, the center structural core, at nearly free-fall acceleration. As you might suspect, this can only mean the center structural support was taken out prior to this collapse.

I can’t think of any way this could happen without an internal detonation, perhaps carefully timed to be masked by the crash of the plane.

There is no reason for what we see here and what we witnessed in the next 15 seconds. None is given. NIST gave up. Maybe you can fill us in :).