The idea of extraterrestrial intelligence has very deep roots in our culture.
Renaissance thinkers were astounded by Galileo’s first telescopic observation of the moons of Jupiter, a system invisible to the naked eye, yet like a miniature solar system in its own right. As the astronomer Kepler said, “Those four little moons exist for Jupiter, not for us… We deduce with the highest degree of probability that Jupiter is inhabited.”
This powerful intuition of the commonness of life has always caused great controversy, just as it does today. Saint Augustine, for example, long ago decided that aliens couldn’t exist. If they did, they would require salvation—a Christ of their own—but that would contradict the uniqueness of Christ, which is theologically unacceptable.
On the other hand there are some who believe that alien visitors have visited the Earth, and may indeed be among us now. Personally I am sceptical about the UFO narrative. I’ve no doubt that many reported sightings are based on something real and observable—odd atmospheric phenomena, sightings of secretive military projects—but I’ve seen or heard of no firm evidence of any extraterrestrial intelligence behind any reported sighting. And it’s just too hard for me to believe that creatures advanced enough to cross the stars would behave in the secretive, vindictive and downright irrational manner many reports claim…
And yet.
If we aren’t programmed by evolution to register something, maybe we simply don’t see it. There is an apocryphal story that Captain Cook encountered islanders who seemed unable to see his great ships, until the crew launched their smaller, more familiar-looking boats to row to shore. The islanders had never seen such huge structures before, and they simply did not have the conceptual equipment to take them in. Similarly, an alien artefact would be in a different category of object to anything previously encountered by a human being, neither of the natural world, nor created by a human. And if a UFO were to visit the Earth, then perhaps elusive, half-seen glimpses, wrongly interpreted in terms of familiar objects, is precisely the kind of “evidence” we should expect.
But don’t quote me on that.
Today, fully trained scientists armed with the most modern equipment are busily searching for evidence of alien minds.
2010 saw the fiftieth anniversary of Project Ozma, the first modern experiment in SETI (Search for Extraterrestrial Intelligence), when, back in 1960, American radio astronomer Frank Drake listened for alien signals from two stars at one frequency for a week. The idea came from a seminal paper published in Nature in 1959 by two physicists, Giuseppe Cocconi and Philip Morrison, who realised that the then relatively new radio telescopes could be used to send signals between the stars: “Few will deny the profound importance, practical and philosophical, which the detection of interstellar communications would have.” In the last few years I’ve become involved with SETI myself, having joined one of the SETI academic task forces, responsible for trying to imagine the consequences of a detection.
But Frank Drake heard nothing in 1960. And after fifty years, surely the most striking thing about modern SETI is that there have been no positive detections. What’s going on?
Advocates of radio-astronomy SETI point out how limited the searches have been so far; only a small number of stars in a small range of frequency domains for limited times have actually been studied. But there have also been unsuccessful searches for other sorts of evidence, such as artefacts at gravitationally stable points in the solar system. Even distant galaxies have been examined, fruitlessly, for signs of cultivation by super-intelligences, as in the Carl Sagan novel Contact and the Robert Zemeckis movie based on it.
Absence of evidence is not evidence of absence; we can’t yet conclude we are alone. Nevertheless it can’t be denied that the sky is not full of radio-noisy, close-by civilisations, as might have been hoped back in 1960.
A paradox is emerging. In Chapter 22 we looked at the origin of life, and ways life could spread naturally from world to world. Life emerged on Earth about as quickly as it could. If it did so here, why not elsewhere? What’s more, our experience of Earth shows us that if life exists, it spreads wherever it can. The Galaxy is big, but old enough for life to have spread across it many times over, even if it travelled at speeds much less than that of light. So where is everybody? This is a development of a back-of-the-envelope argument first made in the 1950s by the great physicist Enrico Fermi (supposedly in the course of a long lunch). It has become known as the Fermi Paradox: if they exist, we should see them.
Possible resolutions of the Paradox have been extensively explored in science fiction, and in science. Perhaps there is some higher form of existence, as unimaginable to us as a Beethoven symphony is unimaginable to a single neuron in its composer’s brain. Or it may be that there are many species—like the dolphins, perhaps—with intelligence but without the opportunity to develop technology, because they live in an aqueous environment, or are spun out among the great rich interstellar clouds. Or maybe they simply aren’t interested. Frank Drake’s radio telescopes would not detect a trace of the Na’vi, inhabitants of the nearest star system, because they have better things to do than build radio transmitters. Or maybe most advanced technological species blow themselves up, as we’ve come close to doing, or exhaust the resources of their world, as in the “ecocide” of the Avatar future.
But to resolve Fermi you have to believe that everybody is the same; all it would take is one exception, one brash, noisy, expansionist, technological species like ourselves to survive the bottleneck of ecocide and war, anywhere nearby, and we would notice them.
Another class of possibilities is that they are indeed here—but they choose not to be seen by us. This kind of notion is generally known as a “zoo hypothesis.” The UFO mythos is an example of this. In Star Trek, the Prime Directive dictates that junior species should be left alone and given room to grow until they have reached star flight capability. Perhaps they really are here, all around us, concealed in some kind of high-tech duck blinds—hiding from us for good intentions, or bad.
A final possible way to resolve Fermi strikes me as the worst of all. What if there are no Na’vi? What if, despite our intuition to the contrary, we are, after all, truly alone? What if our tiny Earth really is the only harbour of advanced life and mind in the cosmos? We saw in Chapter 23 that multicellular life arose quite late in the story of life on Earth. Intelligent life of our technological kind only arose in the last hundred thousand years or so, a tiny fraction (one forty-thousandth) of life’s duration on Earth. So maybe it only happened just the once, right here.
In which case, surely our first duty is not to wipe ourselves out. For if we allow ourselves to become extinct, the universe will continue to unfold according to the mindless logic of physical law, but there will be nobody even to mourn our passing.
You might ask why we so long to discover the alien. Why do we find the idea of meeting the Na’vi so attractive? And why do we long to talk to them?
I have a personal theory that it’s because we aren’t used to being alone. It’s unusual on Earth for there only to be one species of a class of advanced mammal, as humans are unique. There are many species of monkeys, of whales, even of elephants and chimps. The dolphins have complicated social lives that routinely involve interactions between species.
But we have increasing evidence that in the past we did share the world with many other sorts of hominid. The Neanderthals who died out some thirty thousand years ago were probably our closest cousins, but now there is new and exciting evidence of other sorts of humans surviving until quite recently. The diminutive “hobbits” of Indonesia may have lasted until a mere thirteen thousand years ago, and in March 2010 German scientists discovered a bit of bone from a child’s finger, in a cave in Siberia, that came from yet another hominid species that was still around some thirty thousand years ago. So as recently as that we shared the world with at least three cousins, three other twigs from the bushy human family tree, and I wouldn’t be surprised if the future brings more discoveries of this type.
We evolved in a world full of other human types—not just strangers, but creatures of another sort, with minds somewhere between ours and the chimps’. And now that they’re all gone, we know something is missing from the world, even if we don’t know what it is. Maybe we dream of the Na’vi on their world because they remind us of the vanished cousins on our own.
In the universe of Avatar some, at least, of these questions have been answered. But the discovery of the Na’vi on Pandora was a big surprise in many ways.
Humanity is a young species in a very old universe; it was expected that any intelligences out there, if they exist at all, were probably much older than mankind—and perhaps that very advancement was why we couldn’t perceive them. So nobody expected to find stone age humanoids inhabiting a jungle world orbiting the nearest star. But then, nobody expected to find Jupiter-sized worlds orbiting closer to their stars than Mercury does to the sun. The universe is full of surprises; in a way that’s the point of doing science.
But if we do find the alien, will this dream of the future turn into a nightmare of the past?