The floors were each an acre of 4" thick concrete. That may have made a dent? There was more concrete in a WTC floor than there was in the block in the phantom test - and the plane must have hit at least two of them.

110 floors, 4" thick so around 36 acre feet of concrete. And wasn't there some steel in there, too?

What did hold the building up? The steel box sections were made out of 5" thick steel at the base.

The outer walls were load-bearing and so WERE essential to the structure.

The other point about "physics" is that, presumably, this is a well-understood and well-known effect? Can you find another instance anywhere in the world where a steel-framed, high-rise building collapsed into its own footprint at free-fall speed due to a fire?

This one, for instance, is still standing.

The floors were each an acre of 4" thick concrete. That may have made a dent? There was more concrete in a WTC floor than there was in the block in the phantom test - and the plane must have hit at least two of them.

110 floors, 4" thick so around 36 acre feet of concrete. And wasn't there some steel in there, too?

What did hold the building up? The steel box sections were made out of 5" thick steel at the base.

The outer walls were load-bearing and so WERE essential to the structure.

The floors were each an acre of 4" thick concrete. That may have made a dent? There was more concrete in a WTC floor than there was in the block in the phantom test - and the plane must have hit at least two of them.

110 floors, 4" thick so around 36 acre feet of concrete. And wasn't there some steel in there, too?

What did hold the building up? The steel box sections were made out of 5" thick steel at the base.