Judging 9/11 by the Science: The Power of Basic Physics

Photo by jason wilson. (License: Creative Commons Attribution)

Kyle B's recent article on Why 9/11 Conspiracy Theorists are Wrong inspired a spirited but thoughtful discussion of the science of the building collapses of the World Trade Center towers. One of the key pieces of science that surfaced from that discussion was an article linked to by Morwynd from Gordon Ross, a mechanical engineer in the U.K., entitled "Momentum Transfer Analysis of the Collapse of the Upper Storeys of WTC1". This article provides a detailed and highly credible analysis of the physics of what really happens when a steel frame structure collapses into floors beneath it.

Ross' key observation is that many of the published studies of the collapse of these towers treated the problem of one floor of a building falling into another as if the floor receiving the dropping structure were the only floor in the equation. What Ross points out is the most critical of observations: transfer of momentum from the falling floors at the moment of impact on the floor below transfers structural stresses not only to the floor being struck but to several floors beneath it as well acting as a unit in concert with the impacted floor.

You can think of this in terms of simpler architectural structures such as a stone arch in a church or an old bridge: the stress for the top of the arch is carried not only by the stones next to the top keystone but as well by the entire stone structure as it transfers potential momentum from gravity and angular stresses down the pillars that support the arch.

In the conclusion of his analysis Ross notes:

The analysis shows that despite the assumptions made in favour of collapse continuation, vertical movement of the falling section would be arrested prior to completion of the 3% shortening phase of the impacted columns, and within 0.02 secondsafter impact.

A collapse driven only by gravity would not continue to progress beyond that point.

This means that if an entire floor of the World Trade Center were removed instantly and entirely from the structure at the level of the 1WTC plane impact, with no intervening materials - a scenario in fact far more aggressive than that encountered in the actual building collapse - the building structure remaining beneath that section would be able to stop the fall of the descending section of the building in less than a second before it came to a rest atop the remaining section with relatively minimal crumpling of structural steel absorbing the fall.

This is not the scenario that was encountered on September 11, 2001 at the World Trade Center, apparently. Apparently there was some factor - unknown at this point, despite some intelligent conjectures - that did not allow floors beneath the falling section to acts as a unit to provide a transfer of momentum to floors beneath the impact. Moreover, in order to produce the progressive and complete collapse of 1WTC there would have had to have been successive and sequential failures of floors to interrupt the normal transfer of momentum to floors beneath the remaining structure.

Based on this science it appears as if the only way that the towers could have fallen completely is if there had been a complete and systematic elimination of structural integrity throughout the buildings that would allow falling sections to continue their acceleration unopposed by material that could absorb the acceleration via the transfer of momentum.

Or to put it another way: steel frame buildings just don't fall down on their own.

America, we have a problem. Either something was done to eliminate those towers' ability to support falling materials or the laws of physics were violated on 9/11.

As for me, I am voting for the basic truths of physics so well explained by Mr. Ross

I would welcome especially comments by qualified scientists but certainly welcome any and all comments on this article and Ross' supporting materials.

Back To Top