"If we come to the case of flying saucers, for example, we have the difficulty that almost everybody who observes flying saucers sees something different, unless they were previously informed of what they were supposed to see. So the history of flying saucers consists of orange balls of light, blue spheres which bounce on the floor, gray fogs which disappear, gossamer-like streams which evaporate into the thin air, tin, round flat things out of which objects come with funny shapes that are something like a human being. "If you have any appreciation for the complexities of nature and for the evolution of life on earth, you can undestand the tremendous variety of possible forms that life would have. People say life can't exist without air, but it does under water; in fact it started in the sea. You have to be able to move around and have nerves. Plants have no nerves. Just think a few minutes of the variety of life there is. And then you see that the thing that comes out of the saucer isn't going to be anything like what anybody describes. Very unlikely. It's very unlikely that flying saucers would arrive here, in this particular era, without having caused something of a stir earlier. Whay didn't they come earlier? Just when we're getting scientific enough to appreciate the possibility of traveling from one place to another, here come the flying saucers. "There are various arguments of not complete nature that indicate some doubt that the flying saucers are coming from Venus-in fact, considerable doubt. So much doubt that it is going to take alot of accurate experiments, and the lack of consistency and permanency of the characteristics of the observed phenomena means that it isn't there. Most likely. It's not worth paying much more attention to, unless it begins to sharpen up. "I have argued flying saucers with lots of people. (Incidently, I must explain that because I am a scientists does not mean I have not had contact with human beings. Ordinary human beings, I know what they are like. I go to Las Vegas and talk to the show girls and the gamblers and so on. I have banged around alot in my life, so I know about ordinary people.) Anyway, I have to argue about flying saucers on the beach with people, you know. And I was interested in this: they keep arguing that it is possible. And that's true. It is possible. They do not appreciate that the problem is not to demonstrate whether it's possible or not but whether it's going on or not. Whether it's probably occuring or not, not whether it could occur. "That brings me to the fourth kind of attitude toward ideas, and that is that the problem is not what is possible. That's not the problem. The problem is what is probable, what is happening. It does no good to demonstrate again and again that you can't disprove that this could be a flying saucer. We have to guess ahead of time whether we have to worry about the marian invasion. We have to make a judgement about whether it is a flying saucer, whether it's reasonable, whether it's likely. And we do that on the basis of a lot more experience than whether it's just possible, because the number of things that are possible is not fully appreciated by the average individual. And it is also not clear, then, to them how many things that are possible must not be happening. That it's impossible that everything that is possible is happening. And there is too much variety, so most likely anything that you think of that is possible isn't true. In fact that's a general principle in physics theories: no matter what a guy thinks of, it's almost always false. So there have been five or ten theories that have been right in the history of physics, and those are the ones we want. But that doesn't mean everthing is false. We'll find out." Richard P. Feynman The Meaning of it All Thoughts of a Citizen-Scientist Part three: This Unscientific Age pp.75-76 Perseus Books, Reading, Mass. 3rd printing, May 1998 Note on the "Venus" reference: the book consists of the texts of three lectures Feynman gave in April 1963 at the University of Washington, Seattle, as part of the John Danz Lecture series. At that time the notion that flying saucers were from Venus was the prevalent one, probably because of the books of a guy named George Adamski who, much like current alleged UFO contactee Whitley Strieber, got alot of press with his tales of contact with aliens. Adamski reported the aliens said they were Venusians.