The first conspiracy theories about September 11 began to emerge while the wreckage was still smoldering. 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. But an in-depth investigation by Popular Mechanics--first published in the magazine's March 2005 issue, and now expanded into book form--definitively proves that the evidence most often cited by conspiracy theorists is inaccurate, misinterpreted, or false. The book covers the 20 most prominent and persistent claims underlying the conspiracy theories, focusing on concrete, physical facts rather than political hypothesizing. The 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.--From publisher description.