"Clark: You say that scientists are entering ufology in search of physical evidence. But is there physical evidence? And if there is, are they going to find it? What happens if they don't?
Vallee: If I were speaking for them I would say, "Jerry, it's premature to ask those questions." One doesn't know the answers until one really looks - and so far nobody has looked very seriously. So far the people who have looked have been military types searching for enemy craft or direct threats to national security. Or they've been superficial investigators, dedicated civilians with good training but limited time and limited resources.
But you're asking me what I think. I think there are physical data. They are very, very interesting. They may contain a message. My inclination is to look at the message both in a physical sense and in a symbolic sense, but that's because I'm an information scientist and not a physical scientist. I look for the meaning behind the object.
Let me give you an example of what I mean. Recently Paul Cerny investigated a case in northern California in which two older persons saw a UFO take off. Afterwards they saw a sort of ring on the ground. Within the ring they found some molten metal and a pile of sand.
Obviously here is physical evidence. Two tangible things - the molten metal, which turned out to be brass, and the sand. I took some of the latter to a geologist friend who knows about sand. He said it was highly unusual because it did not contain quartz and it was not stream sand or beach sand or residue from mining or anything else. It seemed to be artificial sand created from grinding together stones of different origin.
Well, to a physicist that may not mean too much. It's an indication of something that turns out to be absurd. We can put it alongside other cases of physical traces and then we may start looking for patterns which might lead us to a better understanding of the modus operandi of whoever's doing all this.
In that sense, yes, there is physical evidence. But if you mean physical evidence in the sense that we're going to discover somebody's propulsion system from it, I would have to say I don't expect that to happen.
Clark: Can we infer from the existence of physical evidence, then, that there is a physical cause?
Vallee: If the UFO phenomenon had no physical cause at all, there would be no way for us to perceive it because human beings are physical entities. So it has to make an impression on our senses somehow. For that to take place, it has to be physical at some time.
Clark: So in other words there is such a thing as a solid, three-dimensional flying saucer.
Vallee: No, I didn't say that. That may or may not be true. I don't think there is such a thing as the flying saucer phenomenon. I think it has three components and we have to deal with them in different ways.
First, there is a physical object. That may be a flying saucer or it may be a projection or it may be something entirely different. All we know about it is that it represents a tremendous quantity of electromagnetic energy in a small volume. I say that based upon the evidence gathered from traces, from electromagnetic and radar detection and from perturbations of the electromagnetic fields such as Dr. Claude Poher, the French space scientist, has recorded.
Second, there's the phenomenon the witnesses perceive. What they tell us is that they've seen a flying saucer. Now they may have seen that or they may have seen an image of a flying saucer or they may have hallucinated it under the influence of microwave radiation, or any of a number of things may have happened. The fact is that the witnesses were exposed to an event and as a result they experienced a highly complex alteration of perception which caused them to describe the object or objects that figure in their testimony.
Beyond there - the physical phenomenon and the perception phenomenon - we have the third component, the social phenomenon. That's what happens when the reports are submitted to society and enter the cultural arena. That's the part which I find most interesting."====
http://www.ufoevidence.org/documents/doc608.htm