What do they look like? There is a standard Hollywood convention that extraterrestrials look just like us. Well, maybe they have pointy ears or antennae or green skin, but those are minor cosmetic variations. Extraterrestrials and humans are fundamentally the same. Why should that be? Look at the long sequence of stochastic random events that led to our evolution. I mentioned the extinction of the dinosaurs. That's one. Take another: We have ten fingers. And that's why we use base-ten arithmetic. Nothing special about one, two, three, four, five, six, seven, eight, nine, and then one-zero, except we count on our fingers. Why do we have ten fingers? Because we evolved from a Devonian fish that had ten phalanges in its fins. If we evolved from a Devonian fish that had twelve phalanges, then we'd all be doing base-twelve arithmetic, and base-ten arithmetic would be considered only by mathematicians.
This is true at every level, including biochemical levels, to such an extent that I think it is fair to say-never mind some other planet-if you started the Earth out again and let just these random factors operate, such as when a cosmic ray would strike a chromosome, producing a mutation in the hereditary material, you might wind up with intelligent beings after some thousands of millions of years. You might wind up with creatures of high ethical and artistic or theological accomplishment, But they would not look anything like human beings. We are the products of a unique evolutionary sequence. Unique doesn't mean better; it just means unique. Elsewhere, different environment, different necessity to adapt to changing conditions, a different sequence of random events, including random genetic events, and we should not expect anything like a human being.
Now, what about religion? What about the idea that we are all made in God's image? Is that also a failure of the imagination? What do we mean when we say we are made in God's image? Do we, for example, imagine that God has nostrils and breathes? If so, what does He breathe? Air? Where is the air? Air with oxygen in it? No other planet in the solar system has oxygen except the Earth. Why restrict God to very few places? Why would He need nostrils? What about a navel? Would God have a navel? What about hair? What about a vermiform appendix? What about toes? Toes are clearly the result of our ancestors' life in the canopy of the high forest, swinging from branch to branch. Very good to have four limbs that can hold on to trees. We just happened to have the toes in this particular transitional moment. Big toe is good for balance; little toe is not good for very much at all. It's just an evolutionary accident. Vermiform appendix? Likewise good for nothing. It's just on its way out.
Arthur Clarke has said that Christian orthodoxy is too narrow and timid for what is likely to be found in the search for extraterrestrial intelligence. He has said that the doctrine of man made in the image of God is ticking like a time bomb at Christianity's base, set to explode if other intelligent creatures are discovered. I don't in the least agree. I think that the only sense that can be put on the phrase "made in God's image" is that there is a sense of intellectual affinity between us and higher organisms, if such there be.
The same laws of physics apply everywhere. If we imagine those extraterrestrial beings sending us radio messages, we and they have something in common. We must. The very act of receiving the message means that we have radio technology in common. We have quantum mechanics. We have atomic physics. We have Newtonian gravitation. We can see that those laws of nature apply everywhere in the universe. It's not a question of what your biology is like. It's not a question of the sequence of events that led to you getting a technical civilization. The mere fact that you have a technical civilization means that you have come to grips to some extent with the universe as it really is. And so it is in that sense and in that sense alone, I believe, that it makes sense to talk about such an affinity between advanced beings and ourselves.
Five
I consider the idea of extraterrestrial intelligence a subject of philosophical, scientific, and even historical importance. If we were so lucky as to receive some sign of extraterrestrial intelligence, I think there is little doubt that it would be an extremely significant historical event. And if, on the other hand, we were to make a detailed and comprehensive search to no avail, that would also be something worth knowing It would say something about the rarity and preciousness of intelligent life and again, I believe, would have extremely important and beneficial social consequences. Therefore the search for extraterrestrial life is one of those few circumstances where both a success and a failure would be a success by all standards.
So I am hardly opposed to the idea of extraterrestrials visiting us. If we ourselves are poking around our solar system, if we are capable, as we are, of sending our own spacecraft not just to the other planets in our solar system but beyond our solar system to the stars, then surely other civilizations, if they exist, thousands or millions of years more advanced than ours, ought to be able to achieve interstellar spaceflight much more readily, much more swiftly.
And I don't for a moment deny this as a possibility. I would stress that the economy of effort is far greater for radio communication than direct communication by interstellar spacecraft. I would argue that you can broadcast to millions or thousands of millions of worlds simultaneously, speedily, inexpensively, in a way that even for a very advanced civilization would be much more difficult and costly to do via interstellar spacecraft. However, I certainly could not exclude the possibility that the Earth is now or once was visited. But precisely because the stakes in the answer are high, precisely because this is an issue that engages powerful emotions, we would in this case demand only the most scrupulous standards of evidence.
I want tonight to discuss two modern hypotheses that I think are proper to call folklore, the ancient astronaut hypothesis and the UFO or unidentified flying object hypothesis, and then attempt to connect them with the history of slightly more conventional religions.
The ancient astronaut hypothesis was popularized most effectively by a Swiss hotelier named Erich von Daniken. And his works, the first of which was called Chariots of the Gods? (the question mark becoming suppressed in subsequent printings), were huge bestsellers in the late 1960s, early 1970s, selling worldwide tens of millions of copies, an enormously successful set of books.
The fundamental hypothesis of von Daniken was that there is impressed in the archaeology and folklore and myth of many civilizations on Earth certain indications of past contact with the Earth by extraterrestrial beings. This is not an absurd proposition on the face of it, but how acceptable the hypothesis is depends on how good the evidence is. And, unfortunately, the standards of evidence were extremely poor, in many cases nonexistent. So to give an example (and I promise I am not burlesquing the argument as I describe it), here is von Daniken's approach to the pyramids of Egypt: The pyramids of Egypt, he said, are constructed of individual blocks, rectangular paral-lelopipeds, each of which weighs twenty tons or thereabouts. "Twenty tons," he said. That's extremely heavy. Individual persons could not lift a twenty-ton block, much less many of them, to make a pyramid. Therefore modern construction equipment is necessary, and in 2000 to 3000 B.C., that could only be of extraterrestrial manufacture. Hence extraterrestrials exist.