A Short History of Nearly Everything-第49章

按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！


d　to　be　here。

at　some　time　in　the　last　fifteen　thousand　years　this　blew　in　a　really　big　way。　you’d　have　hadseveral　tens　of　millions　of　tons　of　earth　and　rock　and　superheated　water　blowing　out　athypersonic　speeds。　you　can　imagine　what　it　would　be　like　if　this　happened　under；　say；　theparking　lot　at　old　faithful　or　one　of　the　visitors’　centers。”　he　made　an　unhappy　face。

“would　there　be　any　warning？”

“probably　not。　the　last　significant　explosion　in　the　park　was　at　a　place　called　pork　chopgeyser　in　1989。　that　left　a　crater　about　five　meters　across—not　huge　by　any　means；　but　bigenough　if　you　happened　to　be　standing　there　at　the　time。　fortunately；　nobody　was　around　sonobody　was　hurt；　but　that　happened　without　warning。　in　the　very　ancient　past　there　have　beenexplosions　that　have　made　holes　a　mile　across。　and　nobody　can　tell　you　where　or　when　thatmight　happen　again。　you　just　have　to　hope　that　you’re　not　standing　there　when　it　does。”

big　rockfalls　are　also　a　danger。　there　was　a　big　one　at　gardiner　canyon　in　1999；　but　againfortunately　no　one　was　hurt。　late　in　the　afternoon；　doss　and　i　stopped　at　a　place　where　therewas　a　rock　overhang　poised　above　a　busy　park　road。　cracks　were　clearly　visible。　“it　could　goat　any　time；”　doss　said　thoughtfully。

“you’re　kidding；”　i　said。　there　wasn’t　a　moment　when　there　weren’t　two　cars　passingbeneath　it；　all　filled　with；　in　the　most　literal　sense；　happy　campers。

“oh；　it’s　not　likely；”　he　added。　“i’m　just　saying　it　could。　equally　it　could　stay　like　that　fordecades。　there’s　just　no　telling。　people　have　to　accept　that　there　is　risk　in　ing　here。　that’sall　there　is　to　it。”

as　we　walked　back　to　his　vehicle　to　head　back　to　mammoth　hot　springs；　doss　added：　“butthe　thing　is；　most　of　the　time　bad　things　don’t　happen。　rocks　don’t　fall。　earthquakes　don’toccur。　new　vents　don’t　suddenly　open　up。　for　all　the　instability；　it’s　mostly　remarkably　andamazingly　tranquil。”

“like　earth　itself；”　i　remarked。

“precisely；”　he　agreed。

the　risks　at　yellowstone　apply　to　park　employees　as　much　as　to　visitors。　doss　got　ahorrific　sense　of　that　in　his　first　week　on　the　job　five　years　earlier。　late　one　night；　three　youngsummer　employees　engaged　in　an　illicit　activity　known　as　“hot…potting”—swimming　orbasking　in　warm　pools。　though　the　park；　for　obvious　reasons；　doesn’t　publicize　it；　not　all　thepools　in　yellowstone　are　dangerously　hot。　some　are　extremely　agreeable　to　lie　in；　and　it　wasthe　habit　of　some　of　the　summer　employees　to　have　a　dip　late　at　night　even　though　it　wasagainst　the　rules　to　do　so。　foolishly　the　threesome　had　failed　to　take　a　flashlight；　which　wasextremely　dangerous　because　much　of　the　soil　around　the　warm　pools　is　crusty　and　thin　andone　can　easily　fall　through　into　a　scalding　vent　below。　in　any　case；　as　they　made　their　wayback　to　their　dorm；　they　came　across　a　stream　that　they　had　had　to　leap　over　earlier。　theybacked　up　a　few　paces；　linked　arms　and；　on　the　count　of　three；　took　a　running　jump。　in　fact；　itwasn’t　the　stream　at　all。　it　was　a　boiling　pool。　in　the　dark　they　had　lost　their　bearings。　none　ofthe　three　survived。

i　thought　about　this　the　next　morning　as　i　made　a　brief　call；　on　my　way　out　of　the　park；　at　aplace　called　emerald　pool；　in　the　upper　geyser　basin。　doss　hadn’t　had　time　to　take　me　therethe　day　before；　but　i　thought　i　ought　at　least　to　have　a　look　at　it；　for　emerald　pool　is　a　historicsite。

in　1965；　a　husband…and…wife　team　of　biologists　named　thomas　and　louise　brock；　while　ona　summer　study　trip；　had　done　a　crazy　thing。　they　had　scooped　up　some　of　the　yellowy…brown　scum　that　rimmed　the　pool　and　examined　it　for　life。　to　their；　and　eventually　the　widerworld’s；　deep　surprise；　it　was　full　of　living　microbes。　they　had　found　the　world’s　firstextremophiles—organisms　that　could　live　in　water　that　had　previously　been　assumed　to　bemuch　too　hot　or　acid　or　choked　with　sulfur　to　bear　life。　emerald　pool；　remarkably；　was　allthese　things；　yet　at　least　two　types　of　living　things；　sulpholobus　acidocaldarius　andthermophilus　aquaticus　as　they　became　known；　found　it　congenial。　it　had　always　beensupposed　that　nothing　could　survive　above　temperatures　of　50°c　（122°f）；　but　here　wereorganisms　basking　in　rank；　acidic　waters　nearly　twice　that　hot。

for　almost　twenty　years；　one　of　the　brocks’　two　new　bacteria；　thermophilus　aquaticus；remained　a　laboratory　curiosity　until　a　scientist　in　california　named　kary　b。　mullis　realizedthat　heat…resistant　enzymes　within　it　could　be　used　to　create　a　bit　of　chemical　wizardry　knownas　a　polymerase　chain　reaction；　which　allows　scientists　to　generate　lots　of　dna　from　verysmall　amounts—as　little　as　a　single　molecule　in　ideal　conditions。　it’s　a　kind　of　geneticphotocopying；　and　it　became　the　basis　for　all　subsequent　genetic　science；　from　academicstudies　to　police　forensic　work。　it　won　mullis　the　nobel　prize　in　chemistry　in　1993。

meanwhile；　　scientists　　were　　finding　even　hardier　microbes；　now　known　ashyperthermophiles；　which　demand　temperatures　of　80°c　（176°f）　or　more。　the　warmestorganism　found　so　far；　according　to　frances　ashcroft　in　life　at　the　extremes；　is　pyrolobusfumarii；　which　dwells　in　the　walls　of　ocean　vents　where　the　temperature　can　reach　113°c（235。4°f）。　the　upper　limit　for　life　is　thought　to　be　about　120°c　（248°f）；　though　no　oneactually　knows。　at　all　events；　the　brocks’　findings　pletely　changed　our　perception　of　theliving　world。　as　nasa　scientist　jay　bergstralh　has　put　it：　“wherever　we　go　on　earth—eveninto　what’s　seemed　like　the　most　hostile　possible　environments　for　life—as　long　as　there　isliquid　water　and　some　source　of　chemical　energy　we　find　life。”

life；　it　turns　out；　is　infinitely　more　clever　and　adaptable　than　anyone　had　ever　supposed。

this　is　a　very　good　thing；　for　as　we　are　about　to　see；　we　live　in　a　world　that　doesn’t　altogetherseem　to　want　us　here。

part　v　　　life　itselfthe　more　i　examine　the　universeand　study　the　details　of　its　architecture；the　more　evidence　i　find　that　theuniverse　in　some　sense　must　haveknown　we　were　ing。

…freeman　dyson

x



16LONELY　PLANET

　大＿
it　isn’t　easy　being　an　organism。　in　the　whole　universe；　as　far　as　we　yet　know；　there　isonly　one　place；　an　inconspicuous　outpost　of　the　milky　way　called　earth；　that　will　sustain　you；and　even　it　can　be　pretty　grudging。

from　the　bottom　of　the　deepest　ocean　trench　to　the　top　of　the　highest　mountain；　the　zonethat　covers　nearly　the　whole　of　known　life；　is　only　something　over　a　dozen　miles—not　muchwhen　set　against　the　roominess　of　the　cosmos　at　large。

for　humans　it　is　even　worse　because　we　happen　to　belong　to　the　portion　of　living　thingsthat　took　the　rash　but　venturesome　decision　400　million　years　ago　to　crawl　out　of　the　seas　andbee　land　based　and　oxygen　breathing。　in　consequence；　no　less　than　99。5　percent　of　theworld’s　habitable　space　by　volume；　according　to　one　estimate；　is　fundamentally—in　practicalterms　pletely—off…limits　to　us。

it　isn’t　simply　that　we　can’t　breathe　in　water；　but　that　we　couldn’t　bear　the　pressures。

because　water　is　about　1；300　times　heavier　than　air；　pressures　rise　swiftly　as　you　descend—by　the　equivalent　of　one　atmosphere　for　every　ten　meters　（thirty…three　feet）　of　depth。　on　land；if　you　rose　to　the　top　of　a　five…hundred…foot　eminence—cologne　cathedral　or　the　washingtonmonument；　say—the　change　in　pressure　would　be　so　slight　as　to　be　indiscernible。　at　the　samedepth　underwater；　however；　your　veins　would　collapse　and　your　lungs　would　press　to　theapproximate　dimensions　of　a　coke　can。　amazingly；　people　do　voluntarily　dive　to　such　depths；without　breathing　apparatus；　for　the　fun　of　it　in　a　sport　known　as　free　diving。　apparently　theexperience　of　having　your　internal　organs　rudely　deformed　is　thought　exhilarating　（though　notpresumably　as　exhilarating　as　having　them　return　to　their　former　dimensions　uponresurfacing）。　to　reach　such　depths；　however；　divers　must　be　dragged　down；　and　quite　briskly；by　weights。　without　assistance；　the　deepest　anyone　has　gone　and　lived　to　talk　about　itafterward　was　an　italian　named　umberto　pelizzari；　who　in　1992　dove　to　a　depth　of　236　feet；lingered　for　a　nanosecond；　and　then　shot　back　to　the　surface。　in　terrestrial　terms；　236　feet　isjust　slightly　over　the　length　of　one　new　york　city　block。　so　even　in　our　most　exuberantstunts　we　can　hardly　claim　to　be　masters　of　the　abyss。

other　organisms　do　of　course　manage　to　deal　with　the　pressures　at　depth；　though　quite　howsome　of　them　do　so　is　a　mystery。　the　deepest　point　in　the　ocean　is　the　mariana　trench　in　thepacific。　there；　some　seven　miles　down；　the　pressures　rise　to　over　sixteen　thousand　pounds　persquare　inch。　we　have　managed　once；　briefly；　to　send　humans　to　that　depth　in　a　sturdy　divingvessel；　yet　it　is　home　to　colonies　of　amphipods；　a　type　of　crustacean　similar　to　shrimp　buttransparent；　which　survive　without　any　protection　at　all。　most　oceans　are　of　course　muchshallower；　but　even　at　the　average　ocean　depth　of　two　and　a　half　miles　the　pressure　isequivalent　to　being　squashed　beneath　a　stack　of　fourteen　loaded　cement　trucks。

nearly　everyone；　including　the　authors　of　some　popular　books　on　oceanography；　assumesthat　the　human　body　would　crumple　under　the　immense　pressures　of　the　deep　ocean。　in　fact；this　appears　not　to