People are fascinated with the idea that there are aliens out there; intelligent beings like us, or maybe not like us. This theme has been a staple of television and movies for decades, and is an obsession of UFO buffs. Scientists started the SETI project (Search for Extraterrestrial Intelligence) in the hope of making contact with aliens. But there are no aliens.
How can I be so sure? With tens of billions of galaxies each containing hundreds of billions of stars, many of them like ours, statistics alone would argue for the nonzero probability of life elsewhere in the universe.
Ah, but I do not argue against the probability of extraterrestrial life. It would not surprise me too much if bacteria were found in some moist spot on Mars.
What’s impossible are intelligent aliens; beings that have thoughts, and technologies like radio and space travel and who could communicate with us. Why is that impossible? Because it is oxymoronic. It’s like trying to conceptualize a square circle or a flying pig. You can do it vaguely, in abstractions, as long as you don’t think it through too clearly. But if you give the idea a moment of serious thought, it becomes obvious that it is so muddled, we don’t know what we are talking about.
“Alien” means not like me; foreign in nature; from some other context. Yet we always assume our own context. That’s why E.T. (from the famous movie) looks so remarkably humanoid: one head, frontal eyes, mouth for speaking and eating (language too of course), two arms, two legs, one torso, ten fingers, bipedal locomotion, breathes air, functions in 1g of gravity, and on and on. Sure, he has some special powers and some special needs, but don’t we all. The differences are minor. How alien is E.T.? Not very. He is us.
The old TV show, Star Trek, had some imaginative aliens. My favorite was the Hortas. They were a silicon-based life form (as opposed to our carbon –based) and they looked approximately like a two-foot long gray egg with a fringe around the edge. The fringe presumably was for locomotion, as the Horta were ground dwellers. They looked like big rocks, but they were intelligent, as Spock proved by making a Vulcan mind link with one of them. That was a good representation of an alien that tried to cut through anthropocentric imagery. Nevertheless, the Horta still had thoughts and concerns very much human. It was concerned with territory, safety, family, nutrition and longevity. It didn’t look like us, but it was us.
Another good fictional alien was the race of Krell, the mysterious, extinct beings in the movie, Forbidden Planet, who left behind a gigantic underground computing complex. But surprise, they were not extinct as thought, and when they manifest, they appeared as wavering ghostly shapes of light, a sort of body. It turned out that the Krell were actually projections of the unconscious mind of man, the opposite of alien; extreme intimates of humanity. But their initial representation without a substantial body was innovative.
But why would a real alien have a psychology anything like ours? Would an alien distinguish subjectivity from objectivity, as we do? There’s no reason to think so. Would aliens think of the world as separate from themselves? Could they distinguish themselves as individuals in a group, or not? Maybe they would be absolute individuals. Is intelligence necessarily social? Would alien minds undergo years of socialization as ours do? Would they necessarily have language? Would they be mortal, and if so, would they conceptualize their mortality, and if so, would that mean anything important to them? Would they be susceptible to perceptual illusions (assuming they had perception)? Would they have emotions?
That list goes on endlessly. The fact is, we cannot conceive of a psychology that is very different from our own. We have no reason to expect that we could ever recognize aliens as intelligent beings since only egocentricism prompts us to suppose they would have a psychology like ours. Maybe they’re here now! Maybe the trees are them! That makes about as much sense as anything else.
A related problem is that we have no idea what “intelligence” is, not even in humans, let alone in aliens. We have vague ideas like “smart” versus “dim” people, but we really don’t know how to define that, even for ourselves. So looking for an alien intelligence is looking for something we cannot conceive.
In the movie, Contact, a message from aliens appeared on a computer screen in the pattern of a circle. The scientists looking at it appeared to be gazing into a large hand-mirror. As in fact they were.
The spacecraft Pioneer 10 was launched in 1972 by NASA. It left the solar system after its mission, to fly forever into deep space. The question arose, "What if someday, some intelligent extraterrestrial beings saw our spacecraft floating through deep space, and caught it. Wouldn't it be nice if we had a message for them." So it was decided that a small plaque would be mounted on the spacecraft with a message to the aliens. This is not a Hollywood movie. This actually happened.
What should we say on the plaque? And how? Do aliens know English? What if everyone speaks Spanish in interstellar space? The scientists got around that dilemma by using only pictures and symbols on the plaque. The nine planets of our solar system are shown lined up next to our sun as ten circles. The fourth one from the left (our circle) has an arrow coming off it that points to a little drawing of the spacecraft. Obviously, what we're trying to say here is that this spacecraft came from Earth, third planet from the Sun.
Is that obvious? Would it be obvious to an alien? This plaque is a monument to our ignorance and egocentricism. In what way does a circle represent a planet? Planets aren't circles. And in what way does a line of ten circles represent a solar system? Maybe the illustration means we really like to play billiards here on Earth. As for the arrow on one of the circles, what is an "arrow" anyway? A drawn arrow is a derivative of a hunting arrow, isn't it? Do we suppose that any aliens worth their salt would have used arrows at one time? For hunting space buffalo?
The line drawings of the naked man and woman are uninterpretable. They could be diagrams of electronic circuits. They could be coffee stains. How would an alien even know which side of the drawing was up? The incredible naiveté of the plaque designers seems to suggest that the aliens will look at the drawings and say, "Oh look. On Earth they're parting their hair on the left now."
Even if we allow that aliens might have some experience in common with us about solar systems and hydrogen atoms, it is a vast leap to assume they will also share our concepts of circles, arrows, binary arithmetic, time, distance, figure-ground relationships, spatial orientation, and two-dimensional line drawings. That plaque is just another hand mirror. We cannot conceive of an alien intelligence.
To summarize then. Why are there no intelligent extraterrestrial aliens? For the same reason there are no xlotopopples.