A Short History of Nearly Everything-第13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！


a　hefty　tome　called　annals　of　the　old　testament　；　that　the　earth　had　been1there　will　be　no　testing　here；　but　if　you　are　ever　required　to　memorize　them　you　might　wish　to　remember　johnwilfords　helpful　advice　to　think　of　the　eras　（precambrian；　paleozoic；　mesozoic；　an（　cenozoic）　as　seasons　in　ayear　and　the　periods　（permian；　triassic　jurassic；　etc。）　as　the　months。

created　at　midday　on　october　23；　4004b。c。　；　an　assertion　that　has　amused　historians　andtextbook　writers　ever　since。

2there　is　a　persistent　myth；　incidentally—and　one　propounded　in　many　serious　books—thatussher’s　views　dominated　scientific　beliefs　well　into　the　nineteenth　century；　and　that　it　waslyell　who　put　everyone　straight。　stephen　jay　gould；　in　time’s　arrow；　cites　as　a　typicalexample　this　sentence　from　a　popular　book　of　the　1980s：　“until　lyell　published　his　book；most　thinking　people　accepted　the　idea　that　the　earth　was　young。”　in　fact；　no。　as　martin　j。　s。

rudwick　puts　it；　“no　geologist　of　any　nationality　whose　work　was　taken　seriously　by　othergeologists　advocated　a　timescale　confined　within　the　limits　of　a　literalistic　exegesis　ofgenesis。”　even　the　reverend　buckland；　as　pious　a　soul　as　the　nineteenth　century　produced；noted　that　nowhere　did　the　bible　suggest　that　god　made　heaven　and　earth　on　the　first　day；but　merely　“in　the　beginning。”　that　beginning；　he　reasoned；　may　have　lasted　“millions　uponmillions　of　years。”　everyone　agreed　that　the　earth　was　ancient。　the　question　was　simply　howancient。

one　of　the　better　early　attempts　at　dating　the　planet　came　from　the　ever…reliable　edmondhalley；　who　in　1715　suggested　that　if　you　divided　the　total　amount　of　salt　in　the　world’s　seasby　the　amount　added　each　year；　you　would　get　the　number　of　years　that　the　oceans　had　beenin　existence；　which　would　give　you　a　rough　idea　of　earth’s　age。　the　logic　was　appealing；　butunfortunately　no　one　knew　how　much　salt　was　in　the　sea　or　by　how　much　it　increased　eachyear；　which　rendered　the　experiment　impracticable。

the　first　attempt　at　measurement　that　could　be　called　remotely　scientific　was　made　by　thefrenchman　georges…louis　leclerc；　te　de　buffon；　in　the　1770s。　it　had　long　been　knownthat　the　earth　radiated　appreciable　amounts　of　heat—that　was　apparent　to　anyone　who　wentdown　a　coal　mine—but　there　wasn’t　any　way　of　estimating　the　rate　of　dissipation。　buffon’sexperiment　consisted　of　heating　spheres　until　they　glowed　white　hot　and　then　estimating　therate　of　heat　loss　by　touching　them　（presumably　very　lightly　at　first）　as　they　cooled。　from　thishe　guessed　the　earth’s　age　to　be　somewhere　between　75；000　and　168；000　years　old。　this　wasof　course　a　wild　underestimate；　but　a　radical　notion　nonetheless；　and　buffon　found　himselfthreatened　with　exmunication　for　expressing　it。　a　practical　man；　he　apologized　at　oncefor　his　thoughtless　heresy；　then　cheerfully　repeated　the　assertions　throughout　his　subsequentwritings。

by　the　middle　of　the　nineteenth　century　most　learned　people　thought　the　earth　was　at　leasta　few　million　years　old；　perhaps　even　some　tens　of　millions　of　years　old；　but　probably　notmore　than　that。　so　it　came　as　a　surprise　when；　in　1859　in　on　the　origin　of　species　；　charlesdarwin　announced　that　the　geological　processes　that　created　the　weald；　an　area　of　southernengland　stretching　across　kent；　surrey；　and　sussex；　had　taken；　by　his　calculations；306；662；400　years　to　plete。　the　assertion　was　remarkable　partly　for　being　so　arrestinglyspecific　but　even　more　for　flying　in　the　face　of　accepted　wisdom　about　the　age　of　the　earth。

3itproved　so　contentious　that　darwin　withdrew　it　from　the　third　edition　of　the　book。　the2although　virtually　all　books　find　a　space　for　him；　there　is　a　striking　variability　in　the　details　associated　withussher。　some　books　say　he　made　his　pronouncement　in　1650；　others　in　1654；　still　others　in　1664。　many　cite　thedate　of　earths　reputed　beginning　as　october　26。　at　least　one　book　of　note　spells　his　name　〃usher。〃　the　matter　isinterestingly　surveyed　in　stephen　jay　goulds　eight　little　piggies。

3darwin　loved　an　exact　number。　in　a　later　work；　he　announced　that　the　number　of　worms　to　be　found　in　anaverage　acre　of　english　country　soil　was　53；767。

problem　at　its　heart　remained；　however。　darwin　and　his　geological　friends　needed　the　earth　tobe　old；　but　no　one　could　figure　out　a　way　to　make　it　so。

unfortunately　for　darwin；　and　for　progress；　the　question　came　to　the　attention　of　the　greatlord　kelvin　（who；　though　indubitably　great；　was　then　still　just　plain　william　thomson；　hewouldn’t　be　elevated　to　the　peerage　until　1892；　when　he　was　sixty…eight　years　old　and　nearingthe　end　of　his　career；　but　i　shall　follow　the　convention　here　of　using　the　name　retroactively）。

kelvin　was　one　of　the　most　extraordinary　figures　of　the　nineteenth　century—indeed　of　anycentury。　the　german　scientist　hermann　von　helmholtz；　no　intellectual　slouch　himself；　wrotethat　kelvin　had　by　far　the　greatest　“intelligence　and　lucidity；　and　mobility　of　thought”　of　anyman　he　had　ever　met。　“i　felt　quite　wooden　beside　him　sometimes；”　he　added；　a　bit　dejectedly。

the　sentiment　is　understandable；　for　kelvin　really　was　a　kind　of　victorian　superman。　hewas　born　in　1824　in　belfast；　the　son　of　a　professor　of　mathematics　at　the　royal　academicalinstitution　who　soon　after　transferred　to　glasgow。　there　kelvin　proved　himself　such　aprodigy　that　he　was　admitted　to　glasgow　university　at　the　exceedingly　tender　age　of　ten。　bythe　time　he　had　reached　his　early　twenties；　he　had　studied　at　institutions　in　london　and　paris；graduated　from　cambridge　（where　he　won　the　university’s　top　prizes　for　rowing　andmathematics；　and　somehow　found　time　to　launch　a　musical　society　as　well）；　been　elected　afellow　of　peterhouse；　and　written　（in　french　and　english）　a　dozen　papers　in　pure　and　appliedmathematics　of　such　dazzling　originality　that　he　had　to　publish　them　anonymously　for　fear　ofembarrassing　his　superiors。　at　the　age　of　twenty…two　he　returned　to　glasgow　university　totake　up　a　professorship　in　natural　philosophy；　a　position　he　would　hold　for　the　next　fifty…threeyears。

in　the　course　of　a　long　career　（he　lived　till　1907　and　the　age　of　eighty…three）；　he　wrote　661papers；　accumulated　69　patents　（from　which　he　grew　abundantly　wealthy）；　and　gained　renownin　nearly　every　branch　of　the　physical　sciences。　among　much　else；　he　suggested　the　methodthat　led　directly　to　the　invention　of　refrigeration；　devised　the　scale　of　absolute　temperaturethat　still　bears　his　name；　invented　the　boosting　devices　that　allowed　telegrams　to　be　sentacross　oceans；　and　made　innumerable　improvements　to　shipping　and　navigation；　from　theinvention　of　a　popular　marine　pass　to　the　creation　of　the　first　depth　sounder。　and　thosewere　merely　his　practical　achievements。

his　theoretical　work；　in　electromagnetism；　thermodynamics；　and　the　wave　theory　of　light；was　equally　revolutionary。

4he　had　really　only　one　flaw　and　that　was　an　inability　to　calculatethe　correct　age　of　the　earth。　the　question　occupied　much　of　the　second　half　of　his　career；　buthe　never　came　anywhere　near　getting　it　right。　his　first　effort；　in　1862　for　an　article　in　apopular　magazine　called　macmillan’s　；　suggested　that　the　earth　was　98　million　years　old；　butcautiously　allowed　that　the　figure　could　be　as　low　as　20　million　years　or　as　high　as　400million。　with　remarkable　prudence　he　acknowledged　that　his　calculations　could　be　wrong　if4in　particular　he　elaborated　the　second　law　of　thermodynamics。　a　discussion　of　these　laws　would　be　a　book　initself；　but　i　offer　here　this　crisp　summation　by　the　chemist　p。　w　atkins；　just　to　provide　a　sense　of　them：　〃thereare　four　laws。　the　third　of　them；　the　second　law；　was　recognized　first；　the　first；　the　zeroth　law；　wasformulated　last；　the　first　law　was　second；　the　third　law　might　not　even　be　a　law　in　the　same　sense　as　theothers。〃　in　briefest　terms；　the　second　la　states　that　a　little　energy　is　always　wasted。　you　cant　have　a　perpetualmotion　device　because　no　matter　how　efficient；　it　will　always　lose　energy　and　eventually　run　down。　the　first　lawsays　that　you　cant　create　energy　and　the　third　that　you　cant　reduce　temperatures　to　absolute　zero；　there　willalways　be　some　residual　warmth。　as　dennis　overbye　notes；　the　three　principal　laws　are　sometimes　expressedjocularly　as　（1）　you　cant　win；　（2）　you　cant　break　even；　and　（3）　you　cant　get　out　of　the　game。

“sources　now　unknown　to　us　are　prepared　in　the　great　storehouse　of　creation”—but　it　wasclear　that　he　thought　that　unlikely。

with　the　passage　of　time　kelvin　would　bee　more　forthright　in　his　assertions　and　lesscorrect。　he　continually　revised　his　estimates　downward；　from　a　maximum　of　400　millionyears；　to　100　million　years；　to　50　million　years；　and　finally；　in　1897；　to　a　mere　24　millionyears。　kelvin　wasn’t　being　willful。　it　was　simply　that　there　was　nothing　in　physics　that　couldexplain　how　a　body　the　size　of　the　sun　could　burn　continuously　for　more　than　a　few　tens　ofmillions　of　years　at　most　without　exhausting　its　fuel。　therefore　it　followed　that　the　sun　and　itsplanets　were　relatively；　but　inescapably；　youthful。

the　problem　was　that　nearly　all　the　fossil　evidence　contradicted　this；　and　suddenly　in　thenineteenth　century　there　was　a　lot　of　fossil　evidence。

……



6SCIENCE　RED　IN　TOOTH　AND　CLAW

～　
in　1787；　someone　in　new