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rt…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 petition 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 etary 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 e。
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 bee powerful without being mensurately 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 e from science。 The solutions may well require more of us than just a technological fix。 Many will have to bee 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 munities 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 ets 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 et 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 ets will e roaring out of the Oort Cloud threatening civilizations on many adjacent worlds； we will recognize that a nearby star is about to bee a supernova。 In the really long run； the Sun—on its way to being 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 bee 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 e 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：
For safety； some munities may wish to sever their ties with the rest of humanity—uninfluenced by other societies； other ethical codes； other technological imperatives。 In a time when ets and asteroids are being routinely repositioned； we will be able to populate a small world and then cut it loose。 In successive generations； as this world sped outward； the Earth would fade from bright star to pale dot to invisibility； the Sun would appear dimmer； until it was no more than a vaguely yellow point of light； lost among thousands of others。 The travelers would approach interstellar night。 Some such munities may be content with occasional radio and laser traffic with the old home worlds。 Others； confident of the superiority of their own survival chances and wary of contamination； may try to disappear。 Perhaps all contact with them will ultimately be lost； their very existence forgotten。
Even the resources of a sizable asteroid or et are finite； though； and eventually more resources must be sought elsewhere—especially water； needed for drink； for a breathable oxygen atmosphere； and for hydrogen to power fusion reactors。 So in the long run these munities must migrate from world to world； with no lasting loyalty to any。 We might call it 〃pioneering；〃 or 〃homesteading。〃 A less sympathetic observer might describe it as sucking dry the resources of little world after little world。 But there are a trillion little worlds in the Oort et Cloud。
Living in small numbers on a modest stepmother world far from the Sun； we will know that every scrap of food and every drop of water is dependent on the smooth operation of a
farsighted technology； but these conditions are not radically unlike those to which we are already accustomed。 Digging resources out of the ground and stalking passing resources seem oddly familiar； like a forgotten memory of childhood： It is； with a few significant changes； the strategy of our hunter…gatherer ancestors。 For 99。9 percent of the tenure of humans on Earth； we lived such a life。 Judging from some of the last surviving hunter…gatherers just before they were engulfed by the present global civilization； we may have been relatively happy。 It's the kind of life that forged us。 So after a brief； only partially successful sedentary exp