practically used in building demolition. Thomas pointed out that when Jesse Ventura hired New Mexico Tech to conduct a demonstration showing nanothermite slicing through a large steel beam, the nanothermite produced copious flame and smoke but no damage to the beam, even though it was in a horizontal, and therefore optimal, position. The National Institute of Standards and Technology (NIST) concluded the accepted version was more than sufficient to explain the collapse of the buildings. NIST and many scientists refuse to debate conspiracy theorists because they feel it would give those theories unwarranted credibility. Specialists in structural mechanics and structural engineering accept the model of a fire-induced, gravity-driven collapse of the World Trade Center buildings without the use of explosives. As a result, NIST said that it did not perform any test for the residue of explosive compounds of any kind in the debris. Soon after the day of the attacks, major media sources published that the towers had collapsed due to heat melting the steel. The erroneous claim that the combustion temperature of jet fuel could not melt steel contributed to the belief among skeptics that the towers would not have collapsed without external interference. The basic claim is false, because the combustion temperature of kerosene (jet fuel) is, in fact, more than 500 °C higher than the melting point of structural steel (2093 °C vs. less than 1539 °C). Further, NIST did not claim that the steel melted, but rather that heat softened and weakened the steel, and that weakening, together with the damage caused by the planes' impacts, caused structural collapse. NIST reported that a simulation model based on the simple assumption that combustible vapors burned immediately upon mixing with the incoming air showed that "at any given location, the duration of gas temperatures near 1,000 °C was about 15 to 20 minutes. The rest of the time, the calculated temperatures were 500 °C or below." Pentagon Political activist Thierry Meyssan and filmmaker Dylan Avery claim that American Airlines Flight 77 did not crash into the Pentagon. Instead, they argue that the Pentagon was hit by a missile launched by elements from inside the U.S. government. Some claim that the holes in the Pentagon walls were far too small to have been made by a Boeing 757: "How does a plane 125 ft. wide and 155 ft. long fit into a hole which is only 60 ft.