The first conspiracy theories about September 11 began to emerge while the wreckage was still smoldering. Today, nearly five years later, hundreds of books and thousands of Web pages are devoted to the idea that the U.S. government encouraged, permitted, or actually carried out the attacks. These theories claim to be based on hard evidence. But an in-depth investigation by POPULAR MECHANICS—first published in the magazine’s March 2005 issue, and now greatly expanded into book form—definitively proves that the evidence most often cited by conspiracy theorists is inaccurate, misinterpreted, or false.
 The original article in Popular Mechanics caused a huge groundswell of interest, setting off online debates that continue to this day. Debunking 9/11 Myths expands that investigation to include the 20 most prominent and persistent claims underlying the conspiracy theories, focusing on concrete, physical facts rather than political hypothesizing. Among the issues examined: claims that air traffic control violated standard operating procedures by not immediately intercepting the stricken jets; that the fire caused by the crashes wasn’t actually hot enough to melt steel and cause structural damage in the World Trade Center; that the holes in the Pentagon were too small to have been made by a Boeing 757; and that Flight 93 was actually shot down by an Air Force plane. 
The fascinating and in-depth findings come from leading experts in all the relevant fields, including aviation, air defense, air traffic control, civil engineering, firefighting, metallurgy, and geology.