pale blue dot -carl sagan-第51章

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th　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—〃　pleting　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　〃pletion〃　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　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　fa