Decades after the September 11, 2001, attacks, experts are still working to debunk persistent conspiracy theories surrounding the collapse of the World Trade Center towers. Investigators emphasize that the official findings, attributing the collapses to structural damage from airplane impacts and subsequent fires, are supported by extensive research.
David Dunbar, an investigator and co-author of a prominent 2005 debunking of these theories, expressed frustration with the lack of interest in factual evidence among some conspiracy theorists. "There seemed to be little interest on the part of the conspiracy theorists to do any fact-checking for themselves," Dunbar told the Daily Mail. He noted that some individuals are so emotionally invested in alternative narratives that they are unreceptive to expert analysis.
The roots of the 9/11 conspiracy theories can be traced to figures like Alex Jones, who shortly after the attacks promoted the idea of controlled demolitions and accused the Bush administration of orchestrating the events. This movement prompted Dunbar's team, along with engineers and investigators from the National Institute of Standards and Technology (NIST), to examine the mechanics of the tower collapses.
One of the most common claims is that jet fuel fires could not have caused the steel beams of the towers to weaken sufficiently for collapse, often summarized by the phrase "jet fuel doesn't melt steel beams." Skeptics point out that jet fuel burns at around 1,500 degrees Fahrenheit, well below the melting point of steel (2,750 degrees Fahrenheit). However, Dunbar and other experts explain that the steel did not need to melt. "Steel loses roughly 50 percent of its strength at 1100 degrees Fahrenheit," Dunbar stated, explaining that the intense fires, fueled by the buildings' contents like rugs and furniture, brought temperatures high enough to cause the structural supports to bend and buckle. Forman Williams, a professor of engineering consulted for the Popular Mechanics study, clarified that while jet fuel acted as an ignition source, it was the prolonged burning of the building's interior materials that led to the structural failure.
Another widely circulated theory suggests the visible puffs of dust and debris ejected from the towers during their collapse were evidence of controlled demolitions. Early reports quoted an explosives expert, Van Romero, suggesting this was the case. However, Romero later clarified to Popular Mechanics that he was misquoted and that he never believed explosives brought down the buildings, only that the visual effect resembled an explosion. Investigators explain this phenomenon as the result of "pancaking" floors, where each collapsing floor rapidly compressed the air below it, expelling dust and debris through windows. Shyam Sunder, NIST's lead investigator, explained that this effect, while similar in appearance to small explosions, is a natural consequence of floors failing sequentially.
Dunbar's team also consulted with a demolition company owner to assess the feasibility of a controlled demolition. The expert outlined significant logistical hurdles, including the non-existence of suitable explosives, the immense weight and difficulty of placing such charges covertly, and the fact that controlled demolitions typically involve charges placed at the base of a structure, not spread throughout the upper floors as conspiracy theories suggest. The expert concluded that attempting such a demolition under the circumstances would be "absurd" and indicate a "lack of research on the part of the conspiracy theorists."