Five years later, it's the violent rattling of the ground moments before the World Trade Center's South Tower fell ... that keeps Gary Welz raising questions about just what he survived on Sept. 11, 2001. I felt what was like an earthquake ... just before the South Tower fell," recalls Welz, an adjunct math lecturer at John Jay Criminal College and Fordham University. "The official explanation that I've heard doesn't make sense because it doesn't explain why I heard and felt an explosion before the South Tower fell." Welz is among the growing ranks of conspiracy theorists who question the official explanation of ... the Sept. 11 attacks. The actions of U.S. administrations in recent American history have done nothing to dissuade conspiracy theorists. The details of the 1980s Iran-Contra affair, after all, read like an implausible conspiracy theorist's dream. The Watergate scandal provides fodder too. The Bush administration, it can be argued, has encouraged a new generation of theorists after implying there was a link between Saddam Hussein and the 9/11 attacks ... and insisting Iraq was riddled with weapons of mass destruction. Although he is doubtful of the official 9/11 story, Welz ... does not consider himself a conspiracy theorist. Welz' own skepticism toward 9/11, while based on personal experience, has been reinforced by broadcast quality, highly-polished films on the Internet such as "9/11 Mysteries." There are hundreds of others out there. One such film is "Loose Change" ... a polished, albeit journalistically flawed, attempt to poke holes in the U.S. government's explanation and response to the Sept. 11 attacks. "Loose Change" has been downloaded over 30 million times in 50 countries.