Some of the most famous conspiracy theories involve aliens and UFOs. Remember the Roswell incident? An Air Force surveillance balloon crashed near Roswell, New Mexico, back in 1947. Some people claimed it was actually an extraterrestrial spaceship. By the late 70s, thousands of people believed that all kinds of flying saucers had landed and that the U.S. military was holding actual aliens. So what's with our obsession with UFO conspiracies. David G. Robertson is the guy to ask. He's the author of "UFOs, Conspiracy Theories, and the New Age." He spoke with Rehman Tungekar.