I like what the late, great Carl Sagan said about the subject:
He said that there is a very high mathematical probability that there are numerous intelligent life forms now in existence in our galaxy. The number of intelligent civilizations could, in fact, be fairly substantial.
However, he also said that it is even more mathematically probable that no intelligent life form ever makes contact with any other life form, ever, because of the very great distances that separate them.
In other words, nobody ever finds anybody else, ever.
I think he's very probably correct. Kind of sad, though, huh?
Also, a few years ago I watched a two-hour UFO special on the discovery channel in which a guy made a very convincing case for the idea that almost all the strange things we see in the sky are experimental U.S. aircraft. He cited examples of super-exotic programs that have either come and gone, or continue to be developed.
He said that these are "stealth dirigibles" that are not only radar-evasive, but have a skin-color-changing technology that can make them blend in with the daylight sky:
http://www.space.com/businesstechnology/technology/black_triangle_020805.html
http://www.ufoarea.com/main_triangles.html
He also went on at length about these very different exotic aircraft, saying that they've been in development for over two decades, and feature some sort of fantastic flux drive or something:
They supposedly have ridiculous performance characteristics, and are capable of acceleration, deceleration, and course-changing performance that generates always-fatal G-forces. They're virtually all remote-controlled, he claimed, because they'll kill any personnel that is on board.
These are the "lights" people have seen darting around in the sky in the Nevada desert and elsewhere, he says.
Our tax dollars at work. Personally, this guy's theory makes a ton more sense than the origin of these things being extra-terrrestrial.
