In the aft and side views, all detail had become tiny: integral trees were toothpicks, ponds were drops of glitter, everything seemed embedded in fog. Gold had become a bulge within a larger lens of cloud patterns that trailed off to east and west: a storm pattern that spread across the Smoke Ring. The hidden planet seemed indecently close.
THE INTEGRAL TREES, 1983
THE ALIEN IN OUR MINDS
The only universal message in science fiction reads as follows: There are minds that think as well as we do, or better, but differently.
The appropriate questions are, why do you care? Why should they care? And, where are they?
I want to call your attention to humankind’s ancient fascination with aliens. There’s evolution at work here.
1) Meeting aliens has been a normal thing for humankind. For most of human history, successful tribes have numbered about a hundred. Hunter-gatherer economies need lots of territory, and they have to move frequently.
A hundred thousand years ago, or a million, all humankind was hunter-gatherers. There were strangers around. A wandering tribe might stumble across something different, with odd, ugly faces, bizarre customs, strangely colored skin—and new and useful tools, or new and fearsome weapons.
People who couldn’t deal with aliens had to fight when they met. People who could, had their choices. They could trade, they could make agreements including treaties, they could postpone a fight until they had the advantage, they could set rules for war that would allow more survivors. And . . . a man who can talk persuasively to aliens, can also talk persuasively to his own tribe. A persuasive speaker was likely to become the chief.
But even without the external aliens, there were aliens enough.
2) There were wolves. There were horses. There were saber-toothed cats. There were caribou and pigs and rabbits and woolly mammoths.
A recent article in Analog pointed out that men are cursorial hunters.
Most predators sprint after their prey. Our ancestors didn’t. They picked their target and chased it down over hours or days. A hunter had a better chance of feeding his tribe if he could learn to think like a deer.
So. Somewhere there was a man who found and kept a litter of wolf pups and raised them to know obedience. The tame wolves that didn’t learn to think like men didn’t live to breed. And somewhere there was a man who leapt on a horse’s back and rode it to exhaustion. That tribe had enough to eat, so they didn’t eat the horse. Presently they were riding horses.
So there were horses and dogs within certain tribes of men; but there were aliens closer yet.
3) We are a species of two intelligent genders. Men and women don’t think alike, but we can learn to talk to each other. Some of us. When we choose our mates, we breed for certain traits.
Adults and children don’t think alike. Successful human beings talk to their children. They teach their children to become successful adults. Successful children learn new means of hunting or farming and teach them to their elders. Where the generation gap is too great, that tribe or that family doesn’t survive.
We have dealt with alien intelligences for all of history and prehistory. Wouldn’t that hold for any extraterrestrial intelligence? Maybe not. Aliens may have taken other paths, paths that don’t force negotiation upon them.
Parthenogenesis. Budding instead of sex: no opposite gender. Children might have no intelligence. A human child’s brain is big; it doesn’t grow much while he’s becoming an adult. An alien child’s brain might be the last thing to develop. Or children might hatch from eggs and have to fend for themseives. An adult may never see a child until a young adult comes wandering back out of the breeding grounds. There would then be no intellectual contact with children.
An alien species may have radically divergent genders (as with most insects). If one sex is nonsapient, there is no negotiation. It doesn’t take brains to mate!
Mating seasons are common enough in Earthly life, but look at the result. In mating season both genders might lose all intelligence. Intelligence might be a handicap as regards breeding, even for us, from the evolutionary viewpoint. An intelligent being is likely to think of reasons for not mating with an available partner, or for not having children just now, or at all.
But in mating season male and female do not negotiate before they mate. Males may negotiate with each other, but two males butting heads are very much alike. You might picture the elders of one gender arranging
a mating before the season comes on. This could be done using cages. Lock ‘em up together.
Humankind has been fiddling with reproduction for a long time. Before the Pill there were abortifacients and French letters. Technology may supplant our present modes of reproduction. War between sexes finally becomes a real possibility. One gender exterminated. Technology for reproduction from then on.
What I’m getting at is this. We assume that an alien intelligence will want to talk to us. Or to someone! But it ain’t necessarily so. The evolutionary pressure may not be there.
II
Where are they?
The universe is far older than the oldest known intelligent species. Why haven’t they come visiting? It’s the most interesting question now being asked.
You’ve read tales of the interstellar commonwealth that has been ignoring Earth, or has made So! system into a zoo or national park; but that won’t wash. The kind of power it takes to cross interstellar space is difficult to ignore. Any decent interstellar reaction drive must convert more mass to energy than the mass of the payload; you have to get up to at least a tenth of lightspeed and back down! To take advantage of relativity you would need .9 lights or greater. There would be side effects on a cosmic scale. For laser-augmented light-sails, same remark. We would have seen something—something as powerful as the pulsars, which were assumed to be interstellar beacons until we learned better.
How long does it take to make an intelligent spacegoing species?
Our sample case is the solar system, Earth, and the human species. We’ll stick with our only sample and generalize from there.
The human species seems to be within a thousand years of reaching across to the nearest stars. Our sample is a world big enough to hold a thin atmosphere, orbiting within the liquid water domain of a yellow dwarf star. If we want an oxygen atmosphere we must wait for the life-forms to develop photosynthesis. Our first guess is that it takes four and a half billion years for a planet of this specific type to produce thinking beings.
Keep in mind that other chemistries may form other kinds of life. Even so— Nothing in our temperature domain works as well as water and oxygen and carbon. In hot environments, chemistries are probably too unstable. Within the atmospheres of gas giant planets there are conditions that
might give rise to organic life: you find a layer of Earthiike environment. But escape velocity is very high, and what would they have for tools? In very cold conditions, on Pluto or Titan, or in the black oceans beneath the ice crusts of some of the moons of Jupiter and Saturn, there may be exotic chemistries that can support life. Then again, chemical reactions happen slowiy at such temperatures. We might have to wait longer than the present age of the universe before anything interesting happens.
If we’re looking for something that can build spacecraft, we can stick with our sample and not be too far off.
Four and a haif billion years. Look again and the number goes up. To build a solar system we need gas clouds, galaxies, gravity, heavy elements, and stellar explosions.
The solar system condensed from a relatively dense interstellar cloud. Those aren’t rare, they’re all over the place. The cloud included supernova remnants, the materials that became the cores of planets and the elements of our bodies. The event that caused the condensation may have been a shock wave from a more recent supernova explosion. We need to allow time for previous supernovas, and time to make a triggering supernova.
The galaxies formed near the beginning of the universe. Supernovas have been occurring since a billion years afterward. It’s fair to assume that it takes seven billion years to make an intelligent species.
The universe is generally given as fifteen to eighteen billion years old. Atoms didn’t form for the first half-million years. Call it two billion years to spread supernova remnants throughout the galaxies. The first intelligent species should have evolved seven to ten billion years ago. Based on our own sample, they began exploring space almost at once: say, two or three million years after the taming of fire.
Large numbers of stargoing species should have been expanding though the universe for up to eight billion years. Somewhere a successful industrial species should have gone past the Dyson shell stage into really ambitious engineering projects.
We’re alert enough to recognize Dyson shells now!
Where are they?
Something’s wrong with our assumptions.
III
Maybe they’re all dead.
We can postulate events that regularly destroy an intelligent species before it can reach out to Earth. What follows is likely to be depressing. Hang on. There are answers you’ll like better.
Intelligences may tend to destroy the ecological niche that produced them. We do tend to fiddle. The Zuider Zee is still the world’s biggest successful planetary engineering project, but the Sahara Desert seems to have been caused by goat herding. Rabbits in Australia, garden snails in Tarzana, mongooses in Maui.
We fiddle with life-forms too. Broccoli and pink grapefruit are recent inventions. There are hundreds of breeds of dogs shaped over tens of thousands of years of fooling around. It’s a simple technique: what you don’t like doesn’t breed. But now we know how to fiddle with genetic coding. What are the odds of our making one irrecoverable mistake in the next thousand years?
Destroying one environment in this fashion wouldn’t bother us much if enough of us have left the planet. But let’s look at the energy considerations. Dogs were shaped by primitives who used the wheel if they were wealthy enough. Modem biological experiments can be run for millions of dollars, or less. A decent space station might be built for tens of billions. The odds are that your random ETI developed genetic engineering long before he thought of leaving his planet, because it’s so much cheaper. Where are they? They made one mistake.
Here’s another: nuclear war. Aha, you’ve heard of it. Nuclear war could certainly destroy an environment if it’s done right.
Some nearby star might go supernova. The world need not be wiped clean of life, but a good many species would die or change, including the most complex.
The aliens’ own sun may have turned unstable.
There’s evidence for cycles of destruction on Earth, spaced around 26 million years apart. The causes are in doubt. Even the numbers are in doubt. The cause may be flurries of comets passing through the solar system. The nucleus of a comet is nothing you want to stand in front of. Read LUCIFER’S HAMMER, then multiply the numbers by a thousand. The event that killed the dinosaurs also wiped out most of the life on Earth, and half the species.
What are the odds that a comet or asteroid will intersect some random inhabited world during that brief period after fire and before the ETIs can get off the planet? In the three-million-year period of our existence our own odds are not terrible; but we may be luckier than most worlds.
So much for natural causes.
If you like paranoia, you’ll love the Berserkers. Fred Saberhagen and Greg Benford have different versions, but both involve self-replicating artificial intelligences. Saberhagen’s version is space-going forts left over from some old war, and they’re programmed to destroy all life. Benford’s version was built by old artificial intelligences, and they fear or hate organic intelligences. Both seem plausible, and either would explain our
lack of visitors. If the Berserkers are out there, we must be just on the verge of attracting their attention.
These are the pessimistic assumptions. But let me give you the David Brim theory before you have to go looking for aspirin.
We know of two ways that otherwise Earthlike worlds can go wrong. Venus was too close to the Sun. Too much atmosphere boiled out, and the greenhouse effect kept the surface as hot as a brick kiln. Mars was too small to hold enough atmosphere, and too cold. There’s evidence of liquid water on Mars at some time in the past, but never enough of it for long enough. Earth could have gone in either direction.
What about a third choice? Let’s look at an Earth that’s just a little larger. There’s just a little more water. Astrophysicists are generally happy if they can get within a factor of ten. How much land area would we have if Earth was covered with ten times as much water?
Even twice as much would be too much. Life would develop, we’d get our oxygen atmosphere, but nothing would ever crawl out onto the land because it wouldn’t be worth the effort. Not enough land.
We don’t actually need more water than we have. Let’s give Earth’s core a little less in the way of radioactives. The crust grows thicker, circulation of magma slows down, mountain building becomes much rarer. We get shallow oceans covering a smooth planet.
Something might still develop lungs. A big-brained whale or air-breathing octopus might well develop an interest in optics. There’s water and air to show him how light behaves. He might even find tools for telescopes—breed jellyfish for the purpose—but what would he do about the stars? He’s got no use for the wheel and no access to fire.
There are less restrictive assumptions that could still keep visitors at home.
Our would-be visitor may have evolved for too specific an ecological niche. One lousy lake, or one lousy island, or the growing area for one specific plant, as Koalas depend on eucalyptus. Our ETI may not have the means to conquer large parts of a planet, let alone venture outward. This is certainly true of thousands of Earthly species. Even where some rare species has spread throughout the world, it was usually done by differentiation of species.
And it was done slowly. Our ETI, when we find him, may be subject to biorhythm upset. Even where a planet has been conquered, there may be no contact between parts of it. No airlines, no ships, nothing that moves faster than the speed of a walking alien, because jet lag kills.
A population of ETIs who have conquered their planet and are already suffering from population pressure, may not be able to breed with each other, let alone gather for a summit meeting. But they won’t have wars of conquest either. An invading army would be dead on arrival.
Where are they? Why haven’t they come? We have answers now, though they may not be right.
First: Something kills intelligent beings. It may be natural or artificial. It may be some time bomb ticking away in their own genes. These are the pessimistic assumptions, and they imply that we too are doomed.
Second: The sky may be dense with water worlds, a thousand water worlds for every Earthlike world where land pokes through. But water worlds don’t allow a technology that would lead to spaceflight. They might allow telescopes. Intelligent whales and octopi may be waiting for us all across the sky.
Third: The ETIs may have no interest in talking to us. Even where the interest can be generated, they don’t have the skill for dealing with other minds. The evolutionary basis for that skill may be unique to humankind.
Fourth: The aliens may have adapted too specifically to their ecological niches. They may suffer from extreme biorhythm upset.
If these guesses are right, we have lost something precious. We lose the Draco Tavern and the Mos Eisley spaceport. We lose all of Star Wars. We lose Ensign Flandry and Nicholas Van Rijn and the Kree-Lar Galactic Conference. The only interstellar empires left to us are all human: Dune, and Foundation and Empire, and Jerry Pournelle’s Codominium and Empire of Man before the Moties were found.
But we lose all conflict too, until interstellar war can be waged between human and human.
What’s left? The picture is peculiar precisely because it was so common in science fiction forty years ago. Human explorers cross interstellar space to find and communicate with native wogs. Misunderstandings with the natives may threaten ship and crew, but never Earth.
Water worlds will not be a problem to us. We could build floating bases. The water-dwellers would not perceive us as competitors. Species restricted to one ecological niche would also pose no threat. On the contrary, they might have things to tell us or show us—art forms or philosophical insights if nothing else—and they would likely be glad of our company.
There is hope in the fact that dolphins like us.
As for aliens with no impulse to talk to us—we can give them reasons. We have done very well by talking to aliens. If we manage to settle the worlds of other stars, it will be because we can talk to aliens, and get answers.