A funny thing happened when I saw my first real -- or alleged -- UFO evidence. I was interviewing David Jacobs, a history professor at Temple University in Philadelphia, who investigates alien abductions. I asked him if there was physical proof that abductions are real. "Wanna see?" he answered. Then he left the room, and returned with a T-shirt and a flowered bed sheet, stained, he said, with an alien substance.
   The stains, rather crazily, were shocking pink. (Though why should I think I know anything about alien color schemes?) They had come, Jacobs said, from abductees he'd been working with, after events which, if nothing else, make a wonderful ghost story. Three members of a family had gone to sleep one night, Jacobs told me, the mother on the living room couch, the daughter upstairs in bed, her son at a friend's house down the street. The next morning, all three found these stains on their clothes or their sheets-and so did a fourth person, unrelated, asleep somewhere else in the same neighborhood. All remembered being abducted. (The aliens, according to abduction lore, take whole families. Apparently they also conduct geographical sweeps.)
   Jacobs added that the stains had been studied by (and these are my words now, not his) a recurring character in the ongoing UFO drama, The Scientist Who Can't Be Named, in this case a researcher at a university somewhere in the Midwest who thought he'd be ridiculed if he got publicly connected to UFOs, and very likely would be. His analysis, Jacobs said, showed that the stains were an unknown substance. Cautiously, Jacobs warned that this didn't prove anything, because there are millions of chemical compounds, with new ones discovered or synthesized all the time. Just because a new one appears doesn't mean it's not from earth.
   But clearly Jacobs thought the stains were alien. And-even though he told me all of this with great good humor (realizing, I think, how crazy it all sounds) -- I found myself getting spooked. I don't think I told him that; I don't know if I realized it myself, until later. But I found the whole thing a little scary. It's one thing to read books on abductions and think that aliens might be messing with us; it's something else to have alien goo shoved right under your nose. Suddenly abductions weren't just a theory any more. Suddenly I understood how eerie and just plain horrifying it might be if aliens were really here.

I'm telling this story to illustrate a phenomenon I'm tempted to call UFO denial. I'm a UFO believer; push me up against a wall, and I'll say I think the damn things are real. But I didn't want to believe those stains. I found myself thinking, "Yo, give me a break. Alien stains -- who does Jacobs think he's kidding?" Show me alleged tangible evidence, in other words, and I run away from my belief.
   Other people, I know, may not do this. Members of the UFO group CSETI, for instance, go out at night shining lights to attract alien craft; with no apparent fear, they say that the aliens have answered them. But on the other hand, all the abductees I've spoken to didn't want their abductions to be real. Some told me they broke down crying because they found out someone else apparently had the same experiences. Now they felt they had no choice but to accept that reality.
   And the history of UFOs is full of disbelief, often so bizarre that I think I just might qualify as a cultural guinea pig. I can remember, for example, the amazement that hit the UFO community during the 1960s and 1970s, when British and American researchers began to admit that people might be seeing not just lights and flying disks, but real-life aliens as well.
   There had been a wave of "humanoid" sightings in France in 1954, linked to unknown flying craft. But, for some years afterward, you could read the UFO literature in English and rarely if ever hear of it. Then the '60's hit, and -- appropriately enough, in a revolutionary, psychedelic decade -- soon aliens were all the rage. It's significant, though, that nobody called them aliens. In UFO books and articles, they were most often given the sanitary, almost bureaucratic name "occupants," as exemplified by the title of a 1976 book by respected researchers Jim and Coral Lorenzen, Encounters with UFO Occupants.
   The name suggests, to put it mildly, caution; it evokes an image of minds frozen with surprise, unwilling to label or describe the beings in any way other than to point a finger, and cry out, "They exist!" Caution was justified, it's true, because the sightings really were outlandish. A farmer said he'd been given an alien pancake; another witness was supposedly told the visitors had come for his dog. Over and over, people said they'd seen little UFO creatures gathering twigs and soil samples, almost as if the beings were staging scientific shows for us.
   But quite apart from the content of the stories, there was something shocking, almost forbidden about these tales when they appeared, a sense that a barrier had been breached, which in fact it had been. "Occupant" stories had surfaced all along, but simply hadn't gotten published. And while the Lorenzens' UFO group, APRO (the Aerial Phenomena Research Organization), was now willing to consider these accounts, its rival NICAP (the National Investigations Committee on Aerial Phenomena) was much less quick to bite.
   Perhaps as Richard Hall, who worked for years with NICAP, says, the organization was just being cautious, concerned about what others might think. But an anti-"occupant" prejudice really did exist. Many people were willing to believe that UFOs were alien, but if anyone claimed they'd seen the aliens, well, you can almost imagine a respectable UFO investigator saying, "Uh, excuse me, sir, I've just noticed I have another appointment." The ban extended even to accounts of landed UFOs. It's as if UFO researchers believed in craft from outer space, but (like me, with David Jacobs) didn't want the aliens to get too close.

And when we talk about things that hardcore UFO skeptics won't believe, we begin to hit emotional paydirt. There's every sign that, with them, denial is running rampant. Before going further, let me say (a) that just because skeptics may be in some kind of denial doesn't prove that UFOs are alien, and (b) that it doesn't even prove all skeptics are fools. In fact, we need skeptics. We shouldn't believe that aliens are here unless they really are, and until we're sure, it's helpful to have people acting as defense attorneys, giving all the arguments against.
   But it's hard to read much skeptical UFO literature without concluding that the most prominent skeptics can be zany, not to say wildly out to lunch. Take Carl Sagan, for example, the scientist (and longtime PBS talking head) who sued Apple Computer when the company code named a project "Butthead Astronomer " (Originally they'd called it "Sagan," and changed the name when Sagan objected. He lost the lawsuit, by the way.)
   In his 1973 book The Cosmic Connection, he tells us not just why UFOs aren't visiting, but why they couldn't be. His argument goes more or less like this. Let's suppose, he says, that people see just one genuinely extraterrestrial UFO each year. Actually, of course, there are many more provocative UFO reports than that, but Sagan makes his conservative assumption for a very sly reason. If even one visit is unlikely, he wants to show us, then the number of UFOs actually reported is nothing short of ridiculous.
   And why would even one annual visit be unlikely? Well, you've got to do a little math. You start with the number of technically advanced civilizations there might be in the galaxy. You imagine that they might be sending probes to check out other planets, and you estimate the number of places they might want these probes to visit. Now you do some calculations. How many spaceships would have to be wandering through space before it's likely that one of them would stumble on us once each year?
   The answer turns out to be staggering. Each civilization, Sagan says, would have to launch ten thousand ships each year before we'd have our visitors!
   Case closed, except that it might have struck some readers, just for a start, that the numbers Sagan plays with are pretty arbitrary. Nobody knows how many civilizations there are in the galaxy; all Sagan can do is guess.
   Furthermore, why should we assume as Sagan does, that each solar system has an equally random chance of being visited? Presumably, these magnificent spacefaring races start by looking at the planets nearest to them. If we're in a populated part of the galaxy, we might be visited pretty often.
   But what really kills the argument is another assumption, one so absurd that, quite frankly, it's laughable. Why does each sighting have to represent a fresh interstellar visit? Why couldn't people see the same craft more than once?
   Or, for that matter, why couldn't aliens borrow a scenario from Independence Day (just as the writers of the film borrowed it from countless predecessors), and arrive in one huge ship, which then disgorges an armada of smaller scouts? Voila - hundreds, maybe thousands of UFOs to spot.
   Once you allow for these elementary possibilities, Sagan's argument evaporates. And since the whole thing proves to be nothing more than smoke and mirrors, it's fair to ask why someone so obviously smart would think so stupidly. The most likely answer, I think, is that Sagan wants to believe that UFOs aren't here. You could say he's like those early UFO researchers, who didn't want to believe that UFOs might land. Though Sagan moves the goal posts even further back, by making up reasons not to believe in UFOs at all.

And if you think that's bad, look at Donald Menzel, a Harvard astronomer, now dead, who was the leading UFO skeptic of the '50s and '60s. Menzel, who never saw a UFO case he thought was even mildly plausible, tried to "solve" the 1958 sighting of an Anglican priest, Father Gill. Gill, working as a missionary in New Guinea, said he'd seen a craft hover overhead for many minutes, with beings on board who waved at him. His New Guinean parishioners corroborated his account.
   How did Menzel drive the UFO away? Here, in all its wacky glory, is his analysis, published not in Mad magazine, where it probably belonged, but in a scientific book (UFOs: A Scientific Debate, edited by Carl Sagan and Thornton Page):

    Suppose that the priest, perhaps unknown to himself, has considerable myopia and astigmatism in his eyes. I decided that I could simulate both the myopia and astigmatism with the aid of lenses. From a large selection of spectacle lenses, which I occasionally use in my astronomical experiments, I chose a positive lens that had a certain amount of astigmatism. I removed my spectacles and inserted this lens in one eye, something like a monocle. To my delight, but not to my surprise, Venus and the other stars flattened out and became saucers. But the remarkable thing was an appearance caused by the slightly out-of-focus images of my eyelashes. With a little imagination, these luminous projections, extending above and below the saucer-shaped image, appeared like the men or legs of Father Gill's drawing. The slight movement of my eye, up or down, caused the "men" to move around. The slight irregularities on the hairs of the lashes, perhaps dust or moisture, could easily be interpreted as activity of the "beings" inhabiting the saucer.

So Father Gill stood there for half an hour, watching his eyelashes? Someone who'd imagine such a thing must be wildly anxious to keep UFOs at bay. And Menzel's theory seems even loonier once you know that he made no attempt to check it; he didn't, for example, bother to ask whether Father Gill was astigmatic, or even if he wore glasses of any kind.
   To his credit, Menzel admitted, more or less, that he wasn't exactly on solid ground here; he labeled his analysis mere speculation. But he went on to insist his explanation was "a reasonable one, and much more probable than the alternative, that UFO's were flying over Papua, trying to communicate with the inhabitants."

Now that's a fascinating notion. How, exactly, does Menzel know how unlikely an alien visit to New Guinea or anywhere else might be? This brings us to the centerpiece of UFO denial. In Menzel's time, and also in ours, most top-rank scientists have agreed that UFO visits aren't very probable.
   How do they know that? Well, we've seen Sagan's argument. But most scientists don't need to get that fancy. They're simply convinced that interstellar distances are too vast for anyone to cross. The people most involved in making that argument are, interestingly enough, the ones most concerned with finding alien life. These are the scientists involved in SETI, the "search for extraterrestrial intelligence."
   They're very serious about the quest; they've devoted endless hours (and millions of dollars, in federal and other funding) to an ongoing search for alien radio signals. None have been found, which of course doesn't mean that the quest is useless.
   What's fascinating, though, is the reasoning behind the plan. Frank Drake, an astronomer who's a leader of the SETI adventure, lays it out quite clearly in a book he wrote with a former New York Times science reporter, Dava Sobel, called Is Anyone Out There? He paints a majestic picture of a galaxy filled with intelligent life, some of it a billion years more advanced than we are.
   But this is a lonely picture, too, because none of these civilizations can visit each other. That's why they're forced to communicate by radio, and why it makes sense to listen for their signals. They can't visit each other because, again, the distances are too vast. Journeys would take too long, and would require too much energy. Life, therefore, evolves in isolation all over the galaxy, progressing far beyond us until, as Drake suggests, many races achieve immortality. But still they can't visit each other.
   If this were a movie, we'd hear music swelling on the soundtrack. But does Drake's reasoning make any sense? He's talking about races a billion years beyond us. How can he know what they can and can't do? How could anyone know? There's a smug undertone to the SETI literature. All these scientists freely admit that we don't know anything about life beyond the earth. Then they suggest that, if life really does exist, much of it would be ahead of us. Next thing you know, they're telling us how these civilizations live.
   Somehow, a mystery has evolved into something much more comfortable. We sit in our theoretical armchairs, setting rules for the universe. And one comforting corollary is that, if these vastly powerful races can't visit each other, they certainly can't visit us. The way it works out, in fact, is that we, with barely two hundred years of technology behind us, are going to reach out and discover them . We won't have the messy embarrassment of them finding us first. To quote Jill Tarter, an astrophysicist who is another SETI leading light: "I have a closed mind on the idea that [UFOs are] a manifestation of extraterrestrial visitation."

And if there's any doubt at all that this position is, at bottom, an emotional stance, just follow Drake as he counters disagreement from some of his non-SETI colleagues. Somebody at Cal Tech, he writes, suggests that we could travel large distances in an instant, by burrowing through "wormholes" in space. Sure, says Drake, but "I suspect that for every potential facilitator to long-distance manned spaceflight, we will find an equal number of unknown hazards." Tiny meteors might vaporize our spaceships! Cosmic rays might kill us!
   Right, and maybe aliens will flag us down, eager to sell us hotdogs. Drake has no evidence for any of his fears. He sounds like pundits of the nineteenth century, theorizing that our bones will dissolve if those newfangled railroads travel more than forty miles an hour. I suspect, to use Drake's own phrase, that he simply doesn't want to believe in interstellar travel.
   And his reason, I'm guessing, is that he doesn't want any aliens coming here. We're living, after all, at an interesting time. As a species, we're hovering right at the edge of space. We've been to the moon. We've sent a few probes out into our solar system. With our minds, we've traveled further, populating the universe in movies, TV, and science fiction books with aliens of every description.
   But we really don't know what's out there. We don't know where we fit, or, maybe most scarily, how long we'll be in charge of our own destiny, in a galaxy that might be full of races that can do things we can't even imagine. As a result, we start fantasizing. We develop hopes and fears, including some we don't dare to acknowledge.
   Interestingly, a prominent UFO skeptic, James Oberg, once told me that hopes and fears is where UFOs really come from. They're a myth we've invented, he said, to symbolize our uncertainty about what awaits us in space.
   His theory, though, could just as well explain UFO skepticism; the same uncertainty might make many of us refuse to take UFOs seriously. Assuming for a moment that aliens are really here, I sometimes wonder if they laugh at us, shaking their big bald heads. "We fly right over those poor humans, and still they don't see us!"
   Maybe they've seen it all before. Maybe every planet goes through spasms of denial, when it starts to learn it's not alone.

    [I wrote this for UFO magazine, which never published it. It first appeared in January, 1999 on the UFO City website, run by Peter Robbins, my colleague on Budd Hopkins's Advisory Committee.]