He was talking to Karl Koch, whose company erected the WTC steel. Koch attempted to clarify as follows. “I could see it in my mind’s eye: The fire burned until the steel was weakened and the floors above collapsed, starting a chain reaction of gravity, floor falling upon floor upon floor, clunk – clunk – clunk, the load gaining weight and momentum by the nanosecond, unstoppable. Once enough floors collapsed, the exterior walls and the core columns were no longer laterally supported and folded in.”[12] This is a description of what was called the Pancake Theory, the most widely accepted version of what happened.

The Pancake Theory was promoted by an influential 2002 NOVA video called “Why the Towers Fell,” in which Corley (yet again) and Thornton were the primary commentators. Both of them talked about the floors collapsing, and Thornton described how the perimeter columns buckled outward, not inward as Koch had described. The video made a number of false claims, including exaggeration of the temperatures (2000 F), remarks about melting steel, and the incredible statement that two-thirds of the columns in WTC1 (the North Tower) were completely severed. NIST’s report now indicates that only about 14% of the columns in WTC1 were severed, and in some photos we can count most of these for ourselves.[13]

In August 2004, Underwriters Laboratories evaluated the Pancake Theory by testing models of the floor assemblies used in the WTC buildings. Despite all the previous expert testimony, the floor models did not collapse. NIST reported this in its October 2004 update, in a table of results that clearly showed that the floors did not fail and that, therefore, pancaking was not possible.[14] NIST more succinctly stated this again in its June 2005 draft report, saying: “The results established that this type of assembly was capable of sustaining a large gravity load, without collapsing, for a substantial period of time relative to the duration of the fires in any given location on September 11th.”[15]