PROOF 3: The North Tower disappeared as rapidly as rubble falling through the air.

The Towers disappeared into exploding dust clouds that first consumed their falling tops and then consumed their remaining structures from top to bottom in about 15 seconds as they plummeted to ground. Each Tower's dust cloud grew to several times the building's diameter within a few seconds. Thus the majority of each Tower's material was falling freely through the air, outside the building's footprint. Only air resistance slowed the descent of these materials, accounting for about a 50 percent slowdown compared to the rate of free-fall in a vacuum. No portion of either tower remained standing above the descending cloud.

At 8.5 seconds into its collapse the top of the North Tower's cloud of dust and steel fragments was falling at about 50 feet per second both inside and outside the Tower's profile. This proves that the falling rubble was not crushing the tower.

Air resistance slowed the descent of the rubble outside the building's profile by about 50 percent. And yet the over 1000 vertical feet of intact structure did not slow portions falling within the profile any more than air. This can be verified by examining the top of the descending dust cloud, which is essentially the same height both inside and outside the profile of the North Tower.

Each Tower was supported by a lattice of 90,000 tons of steel strong enough to resist earthquakes and hurricane-force winds. To believe the Official Story requires one to think that these immensely strong structures provided no more resistance to falling rubble than did air.