Yes, imperceptibly "brief but violent collisions" are what forced 80 and 90 intact floors of steel and concrete highrise (with furnishings, walls, mechanical equipment, massive filing systems, plumbing, 7-ton floor pans, stairwells, people etc..) to self-pulverize, at the rate of 0.15 seconds per floor, with nothing but shredded columns and miles and miles of dust to show for it at the bottom. As some point out, not even a toilet. All from gravity!
Human bodies dismembered, segmented into tiny pieces. Bones shattered into fragments less than 1 inch long, ejected laterally onto neigbouring rooftops. All from gravity.
And the fact remaining that no steel-framed highrise has ever, or since, collapsed to the ground from floor fires. Nor even from raging infernos.
This is quack science. Beedunker-level science.