We're not sure if this stock photo includes a real alien or if perhaps it's a creative sculpture, but we can say with some authority that the thing in the jar resembles the popular image of aliens.

Stanton Friedman is convinced that extraterrestrial aliens are visiting us, and have been for a long time. There's nothing odd about that; many people believe in UFOs and aliens.

But Friedman is not your typical tin foil-hatted UFO nut. For one thing, he has a Master's degree in nuclear physics and worked for decades on fusion and fission rockets for some of the world's top aerospace companies.

Friedman joins other famous people with advanced degrees who are firmly convinced about things for which there is little hard evidence. Former Apollo astronaut Edgar Mitchell, for example, shares Friedman's beliefs about UFOs and alien cover-ups (Mitchell admits that he never saw any UFOs during his time with NASA, but believes that in 1947 Roswell, New Mexico, "There was a UFO crash. There was an alien spacecraft").

Another respected UFO believer was the late Harvard psychiatrist John Mack, who spent years studying people allegedly abducted, probed, and experimented upon by aliens.

Friedman has cultivated an image of a maverick, a renegade scientist brave enough to tell the world what he knows about flying saucers. He has spent the last half-century researching UFO claims, and his conclusion is that "Some UFOs are intelligently controlled extraterrestrial spacecraft, and this is the biggest story of the millennium.... I'm convinced we're dealing here with a cosmic Watergate," he told AOL News this week. "A few people within major governments have known since at least 1947 that some UFOs are alien spacecraft." According to Friedman, there are two main reasons that the hard evidence of alien presence is not better known:

The first is that a decades-long global conspiracy is afoot; high-ranking officials have carefully covered up all the hard evidence of UFOs. The second that scientists who are in a position to help expose the truth are afraid—not just of those enforcing the conspiracy, but of admitting they were wrong. Friedman believes that the real truth about UFOs will be revealed soon.

"I'm still optimistic that, within my lifespan—and I'm 75—we'll get at least a part of the story, that we're not alone in the universe," he said.

He may be right. It's possible that next week, next year, or next decade the long-sought and ever-elusive hard evidence proving that aliens exist will finally surface. However, Friedman might note a "curse" on UFO conspiracy theorists that famed skeptical UFO investigator Phillip Klass issued in his last will and testament:

"No matter how long you live, you will never know any more about UFOs than you know today," Klass wrote. "You will never know any more about what UFOs really are, or where they come from. You will never know any more about what the U.S. Government really knows about UFOs than you know today. As you lie on your own death-bed you will be as mystified about UFOs as you are today."

Klass died in 2005, and so far his curse remains in effect.

Benjamin Radford is managing editor of the Skeptical Inquirer science magazine. His new book Scientific Paranormal Investigation has just been released; this and his other books and projects can be found on his website. His Bad Science column appears regularly on LiveScience.