After half a century of investigation, a former nuclear physicist -- who worked on fission and fusion rockets for companies like Westinghouse and Aerojet General Nucleonics -- is convinced that not only are UFOs real, the government has known about them since 1947. Some UFOs are intelligently controlled extraterrestrial spacecraft," Stanton Friedman told AOL News, calling the vast cover-up of their existence "the biggest story of the millennium." In 1958, UFOs caught his attention, and Friedman has since lectured about this subject at more than 700 colleges and professional groups in all 50 states and around the world. "After 53 years of investigation, I'm convinced we're dealing here with a cosmic Watergate," he [said]. "That means a few people within major governments have known since at least 1947 that some UFOs are alien spacecraft." In Friedman's new book, Science Was Wrong: Startling Truths About Cures, Theories, and Inventions "They" Declared Impossible, co-authored with Kathleen Marden, he wrote, "There's been no shortage of strong, negative proclamations from debunking groups and individuals who refuse to examine the evidence ... to support the notion that some UFOs are of extraterrestrial origin.