THE MOON WAS WHERE the tree of immortality grew in ancient Chinese myth. The tree of longevity if not of immortality, it seems, indeed grows on other worlds. If we were up there among the planets, if there were self-sufficient human communities oil many worlds, our species would be insulated from catastrophe. The depletion of the ultraviolet-absorbing shield on one world would, if anything, be a warning to take special care of the shield on another. A cataclysmic impact on one world would likely leave all the others untouched. The more of us beyond the Earth, the greater the diversity of worlds we inhabit, the more varied the planetary engineering, the greater the range of societal standards and values—then the safer the human species will be.
If you grow up living underground in a world with a hundredth of an Earth gravity and black skies through the portals, you have a very different set of perceptions, interests, prejudices, and predispositions than someone who lives on the surface of the home planet. Likewise if you live on the surface of Mars in the throes of terraforming, or Venus, or Titan. This strategy—breaking up into many smaller self-propagating groups, each with somewhat different strengths and concerns, but all marked by local pride—has been widely employed in the evolution of life on Earth, and by our own ancestors in particular. It may, in fact, be key to understanding why we humans are the way we are.1 This is the second of the missing justifications for a permanent human presence in space: to improve our chances of surviving, not just the catastrophes we can foresee, but also the ones we cannot. Gott also argues that establishing human communities on other worlds may offer us our best chance of beating the odds.
To take out this insurance policy is not very expensive, not on the scale on which we do things on Earth. It would not even require doubling the space budgets of the present spacefaring nations (which, in all cases, are only a small fraction of the military budgets and many other voluntary expenditures that might be considered marginal or even frivolous). We could soon be setting humans down on near-Earth asteroids and establishing bases on Mars. We know how to do it, even with present technology, in less than a human lifetime. And the technologies will quickly improve. We will get better at going into space.
A serious effort to send humans to other worlds is relatively so inexpensive on a per annum basis that it cannot seriously compete with urgent social agendas on Earth. If we take this path, streams of images from other worlds will be pouring down on Earth at the speed of light. Virtual reality will make the adventure accessible to millions of stay-on-Earths. Vicarious participation will be much more real than at any earlier age of exploration and discovery. And the more cultures and people it inspires and excites, the more likely it will happen.
But by what right, we might ask ourselves, do we inhabit, alter, and conquer other worlds? If anyone else were living in the Solar System, this would be an important question. If, though, there's no one else in this system but us, don't we have a right to settle it?
Of course, our exploration and homesteading should be enlightened by a respect for planetary environments and the scientific knowledge they hold. This is simple prudence. Of course, exploration and settlement ought to be done equitably and transnationally, by representatives of the entire human species. Our past colonial history is not encouraging in these regards; but this time we are not motivated by gold or spices or slaves or a zeal to convert the heathen to the One True Faith, as were the European explorers of the fifteenth and sixteenth centuries. Indeed, this is one of the chief reasons we're experiencing such intermittent progress, so many fits and starts in the manned space programs of all nations.
Despite all the provincialisms I complained about early in this book, here I find myself an unapologetic human chauvinist. If there were other life in this solar system, it would be in imminent danger because the humans are coming. In such a case, I might even be persuaded that safeguarding our species by settling certain other worlds is offset, in part at least, by the danger we would pose to everybody else. But as nearly as we can tell, so far at least, there is no other life in this system, not one microbe. There's only Earthlife.
In that case, on behalf of Earthlife, I urge that, with full knowledge of our limitations, we vastly increase our knowledge of the Solar System and then begin to settle other worlds.
These are the missing practical arguments: safeguarding 'the Earth from otherwise inevitable catastrophic impacts and hedging our bets on the many other threats, known and unknown, to the environment that sustains us. Without these arguments, a compelling case for sending humans to Mars and elsewhere might be lacking. But with them—and the buttressing arguments involving science, education, perspective, and hope—I think a strong case can be made. If our long-term survival is at stake, we have a basic responsibility to our species venture to other worlds.
Sailors on a becalmed sea, we sense the stirring of a breeze.
CHAPTER 22: TIPTOEING THROUGH THE MILKY WAY
I swear by the shelters of the stars (a mighty oath, if you but knew it) . . .
—THE QUR'AN, SURA 56 (7TH CENTURY)
Of course, it is strange to inhabit the earth no longer,
To give up customs one barely had time to learn . . .
—RAINER MARIA RILKE, "THE FIRST ELEGY" (1923)
The prospect of scaling heaven, of ascending to the sky, of altering other worlds to suit our purposes—no matter how well intentioned we may be—sets the warning flags flying: We remember the human inclination toward overweening pride; we recall our fallibility and misjudgments when presented with powerful new technologies. We recollect the story of the Tower of Babel, a building "whose top may reach unto heaven," and God's fear .shout our species, that now "nothing will be restrained from them which they have imagined to do."
We come upon Psalm 15, which stakes a divine claim to other worlds: "[T]he heavens are the Lord's, but the Earth lath he given to the children of men." Or Plato's retelling of the Greek analogue of Babel—the tale of Otys and Ephialtes. They were mortals who "dared to scale heaven." The gods were faced with a choice. Should they kill the upstart humans "and annihilate [their] race with thunderbolts"? On the one Band, "this would be the end of the sacrifices and worship which mien offered" the gods and which gods craved. "But, on the other hand, the gods could not suffer [such] insolence to be unrestrained.''
If, in the long term, though, we have no alternative, if our choice really is many worlds or none, we are in need of other sorts of myths of encouragement. They exist. Many religions, from Hinduism to Gnostic Christianity to Mormon doctrine, teach that—as impious as it may sound—it is the goal of humans to become gods. Or consider a story in the Jewish Talmud left out of the Book of Genesis. (It is in doubtful accord with the account of the apple, the Tree of Knowledge, the Fall, and the expulsion from Eden.) In the Garden, God tells Eve and Adam that He has intentionally left the Universe unfinished. It is the responsibility of humans, over countless generations, to participate with God in a "glorious" experiment—" completing the Creation."
The burden of such a responsibility is heavy, especially on so weak and imperfect a species as ours, one with so unhappy a history. Nothing remotely like "completion" can be attempted without vastly more knowledge than we have today. But perhaps, if our very existence is at stake, we will find ourselves Able to rise to this supreme challenge.
ALTHOUGH HE DID NOT quite use any of the arguments of the preceding chapter, it was Robert Goddard's intuition that "the navigation of interplanetary space must be effected to ensure the continuance of the race." Konstantin Tsiolkovsky made a similar judgment:
There are countless planets, like many island Earths . . . Man occupies one of them. But why could he not avail himself of others, and of the might of numberless suns? . . . When the Sun has exhausted its energy, it would be logical to leave it and look for another, newly kindled, star still in its prime.
This might be done earlier, he suggested, long before the Sun dies, "by adventurous souls seeking fresh worlds to conquer."
But as
I rethink this whole argument, I'm troubled. Is it too much Buck Rogers? Does it demand an absurd confidence in future technology? Does it ignore my own admonitions about human fallibility? Surely in the short term it's biased against technologically less-developed nations. Are there no practical alternatives that avoid these pitfalls?
All our self-inflicted environmental problems, all our weapons of mass destruction are products of science and technology. So, you might say, let's just back off from science and technology. Let's admit that these tools are simply too hot to handle. Let's create a simpler society, in which no matter how careless or short-sighted we are, we're incapable of altering the environment on a global or even on a regional scale. Let's throttle back to a minimal, agriculturally intensive technology, with stringent controls on new knowledge. An authoritarian theocracy is a tried-and-true way to enforce the controls.
Such a world culture is unstable, though, in the long run if not the short—because of the speed of technological advance. Human propensities for self-betterment, envy, and competition will always be throbbing subsurface; opportunities for short-term, local advantage will sooner or later be seized. Unless there are severe constraints on thought and action, in a flash we'll be back to where we are today. So controlled a society must grant great powers to the elite that does the controlling, inviting flagrant abuse and eventual rebellion. It's very hard—once we've seen the riches, conveniences, and lifesaving medicines that technology offers—to squelch human inventiveness and acquisitiveness. And while such a devolution of the global civilization, were it possible, might conceivably address the problem of self-inflicted technological catastrophe, it would also leave us defenseless against eventual asteroidal and cometary impacts.
Or you might imagine throttling back much further, back to hunter-gatherer society, where we live off the natural products of the land and abandon even agriculture. Javelin, digging stick, bow, arrow, and fire would then be technology enough. But the Earth could support at the very most a few tens of millions of hunter-gatherers. How could we get down to such low population levels without instigating the very catastrophes we are trying to avoid? Besides, we hardly know how to live the hunter-gatherer life anymore: We've forgotten their cultures, their skills, their tool-kits. We've killed off almost all of them, and we've destroyed much of the environment that sustained them. Except for a tiny remnant of us, we might not be able, even if we gave it high priority, to go back. And again, even if we could return, we would be helpless before the impact catastrophe that inexorably will come.
The alternatives seem worse than cruel: They are ineffective. Many of the dangers we face indeed arise from science and technology—but, more fundamentally, because we leave become powerful without becoming commensurately wise. The world-altering powers that technology has delivered into our hands now require a degree of consideration and foresight that has never before been asked of us.
Science cuts two ways, of course; its products can be used for both good and evil. But there's no turning back from science. The early warnings about technological dangers also come from science. The solutions may well require more of us than just a technological fix. Many will have to become scientifically literate. We may have to change institutions and behavior. But our problems, whatever their origin, cannot be solved apart from science. The technologies that threaten us and the circumvention of those threats both issue from the same font. They are racing neck and neck.
In contrast, with human societies on several worlds, our prospects would be far more favorable. Our portfolio would be diversified. Our eggs would be, almost literally, in many baskets. Each society would tend to be proud of the virtues of its world, its planetary engineering, its social conventions, its hereditary predispositions. Necessarily, cultural differences would be cherished and exaggerated. This diversity would serve as a tool of survival.
When the off Earth settlements are better able to fend for themselves, they will have every reason to encourage technological advance, openness of spirit, and adventure—even if those left on Earth are obliged to prize caution, fear new knowledge, and institute Draconian social controls. After the first few self-sustaining communities are established on other worlds, the Earthlings might also be able to relax their strictures and lighten up. The humans in space would provide those on Earth with real protection against rare but catastrophic collisions by asteroids or comets on rogue trajectories. Of course, for this very reason, humans in space would hold the upper hand in any serious dispute with those on Earth.
The prospects of such a time contrast provocatively with forecasts that the progress of science and technology is now near some asymptotic limit; that art, literature, and music are never to approach, much less exceed, the heights our species has, on occasion, already touched; and that political life on Earth is about to settle into some rock-stable liberal democratic world government, identified, after Hegel, as "the end of history." Such an expansion into space also contrasts with a different but likewise discernible trend in recent times—toward authoritarianism, censorship, ethnic hatred, and a deep suspicion of curiosity and learning. Instead, I think that, after some debugging, the settlement of the Solar System presages an open-ended era of dazzling advances in science and technology; cultural flowering; and wide-ranging experiments, up there in the sky, in government and social organization. In more than one respect, exploring the Solar System and homesteading other worlds constitutes the beginning, much more than the end, of history.
IT'S IMPOSSIBLE, for us humans at least, to look into our future, certainly not centuries ahead. No one has ever done so with any consistency and detail. I certainly do not imagine that I can. I have, with some trepidation, gone as far as I have to this point in the book, because we are just recognizing the truly unprecedented challenges brought on by our technology. These challenges have, I think, occasional straightforward implications, some of which I've tried briefly to lay out. There are also less straightforward, much longer-term implications about which I'm even less confident. Nevertheless, I'd like to present them too for your consideration:
Even when our descendants are established on near-Earth asteroids and Mars and the moons of the outer Solar System and the Kuiper Comet Belt, it still won't be entirely safe. In the long run, the Sun may generate stupendous X-ray and ultraviolet outbursts; the Solar System will enter one of the vast interstellar clouds lurking nearby and the planets will darken and cool; a shower of deadly comets will come roaring out of the Oort Cloud threatening civilizations on many adjacent worlds; we will recognize that a nearby star is about to become a supernova. In the really long run, the Sun—on its way to becoming a red giant star—will get bigger and brighter, the Earth will begin to lose its air and water to space, the soil will char, the oceans will evaporate and boil, the rocks will vaporize, and our planet may even be swallowed up into the interior of the Sun.
Far from being made for us, eventually the Solar System will become too dangerous for us. In the long run, putting all our eggs in a single stellar basket, no matter how reliable the Solar System has been lately, may be too risky. In the long run, as Tsiolkovsky and Goddard long ago recognized, we need to leave the Solar System.
If that's true for us, you might very well ask, why isn't it true for others? And if it is true for others, why aren't they here? There are many possible answers, including the contention that they have come here—although the evidence for that is pitifully slim. Or there may be no one else out there, because they destroy themselves, with almost no exceptions, before they achieve interstellar flight; or because in a galaxy of 400 billion suns ours is the first technical civilization.
A more likely explanation, I think, issues from the simple fact that space is vast and the stars are far apart. Even if there were civilizations much older and more advanced than we—expanding out from their home worlds, reworking new worlds, and then continuing onward to other stars—they would be unlikely, according to calculations performed by William I. Newman of UCLA and me, to be
here. Yet. And because the speed of light is finite, the TV and radar news that a technical civilization has arisen on some planet of the Sun has not reached them. Yet.
Should optimistic estimates prevail and one in every million stars shelters a nearby technological civilization, and if as well they're randomly strewn through the Milky Way—were these provisos to hold—then the nearest one, we recall, would be a few hundred light-years distant: at the closest, maybe 100 lightyears, more likely a thousand light-years-and, of course, perhaps nowhere, no matter how far. Suppose the nearest civilization on a planet of another star is, say, 200 light-years away. Then, some 150 years from now they'll begin to receive our feeble post-World War II television and radar emission. What will they make of it? With each passing year the signal will get louder, more interesting, perhaps more alarming. Eventually, they may respond: by returning a radio message, or by visiting. In either case, the response will likely be limited by the finite value of the speed of light. With these wildly uncertain numbers, the answer to our unintentional mid-century call into the depths of space will not arrive until around the year 2350. If they're farther away, of course, it will take longer; and if much farther away, much longer. The interesting possibility arises that our first receipt of a message from an alien civilization, a message intended for us (not just an all-points bulletin), will occur in a time when we are well situated on many worlds in our solar system and preparing to move on.
With or without such a message, though, we will have reason to continue outward, seeking other solar systems. Or—even safer in this unpredictable and violent sector of the Galaxy—to sequester some of us in self-sufficient habitations in interstellar space, far from the dangers constituted by the stars. Such a future would, I think, naturally evolve, by slow increments, even without any grand goal of interstellar travel: