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:

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.