A Short History of Nearly Everything-第26章

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　way　but　of　lots　of　independent　galaxies—“islanduniverses”—many　of　them　bigger　than　the　milky　way　and　much　more　distant。

this　finding　alone　would　have　ensured　hubble’s　reputation；　but　he　now　turned　to　thequestion　of　working　out　just　how　much　vaster　the　universe　was；　and　made　an　even　morestriking　discovery。　hubble　began　to　measure　the　spectra　of　distant　galaxies—the　business　thatslipher　had　begun　in　arizona。　using　mount　wilson’s　new　hundred…inch　hooker　telescopeand　some　clever　inferences；　he　worked　out　that　all　the　galaxies　in　the　sky　（except　for　our　ownlocal　cluster）　are　moving　away　from　us。　moreover；　their　speed　and　distance　were　neatlyproportional：　the　further　away　the　galaxy；　the　faster　it　was　moving。

this　was　truly　startling。　the　universe　was　expanding；　swiftly　and　evenly　in　all　directions。　itdidn’t　take　a　huge　amount　of　imagination　to　read　backwards　from　this　and　realize　that　it　musttherefore　have　started　from　some　central　point。　far　from　being　the　stable；　fixed；　eternal　voidthat　everyone　had　always　assumed；　this　was　a　universe　that　had　a　beginning。　it　mighttherefore　also　have　an　end。

the　wonder；　as　stephen　hawking　has　noted；　is　that　no　one　had　hit　on　the　idea　of　theexpanding　universe　before。　a　static　universe；　as　should　have　been　obvious　to　newton　andevery　thinking　astronomer　since；　would　collapse　in　upon　itself。　there　was　also　the　problemthat　if　stars　had　been　burning　indefinitely　in　a　static　universe　they’d　have　made　the　wholeintolerably　hot—certainly　much　too　hot　for　the　likes　of　us。　an　expanding　universe　resolvedmuch　of　this　at　a　stroke。

hubble　was　a　much　better　observer　than　a　thinker　and　didn’t　immediately　appreciate　thefull　implications　of　what　he　had　found。　partly　this　was　because　he　was　woefully　ignorant　ofeinstein’s　general　theory　of　relativity。　this　was　quite　remarkable　because；　for　one　thing；einstein　and　his　theory　were　world　famous　by　now。　moreover；　in　1929　albert　michelson—now　in　his　twilight　years　but　still　one　of　the　world’s　most　alert　and　esteemed　scientists—accepted　a　position　at　mount　wilson　to　measure　the　velocity　of　light　with　his　trustyinterferometer；　and　must　surely　have　at　least　mentioned　to　him　the　applicability　of　einstein’stheory　to　his　own　findings。

at　all　events；　hubble　failed　to　make　theoretical　hay　when　the　chance　was　there。　instead；　itwas　left　to　a　belgian　priest…scholar　（with　a　ph。d。　from　mit）　named　georges　lema？tre　tobring　together　the　two　strands　in　his　own　“fireworks　theory；”　which　suggested　that　theuniverse　began　as　a　geometrical　point；　a　“primeval　atom；”　which　burst　into　glory　and　hadbeen　moving　apart　ever　since。　it　was　an　idea　that　very　neatly　anticipated　the　modernconception　of　the　big　bang　but　was　so　far　ahead　of　its　time　that　lema？tre　seldom　gets　morethan　the　sentence　or　two　that　we　have　given　him　here。　the　world　would　need　additionaldecades；　and　the　inadvertent　discovery　of　cosmic　background　radiation　by　penzias　and　wilsonat　their　hissing　antenna　in　new　jersey；　before　the　big　bang　would　begin　to　move　frominteresting　idea　to　established　theory。

neither　hubble　nor　einstein　would　be　much　of　a　part　of　that　big　story。　though　no　onewould　have　guessed　it　at　the　time；　both　men　had　done　about　as　much　as　they　were　ever　goingto　do。

in　1936　hubble　produced　a　popular　book　called　the　realm　of　the　nebulae；　whichexplained　in　flattering　style　his　own　considerable　achievements。　here　at　last　he　showed　thathe　had　acquainted　himself　with　einstein’s　theory—up　to　a　point　anyway：　he　gave　it　four　pagesout　of　about　two　hundred。

hubble　died　of　a　heart　attack　in　1953。　one　last　small　oddity　awaited　him。　for　reasonscloaked　in　mystery；　his　wife　declined　to　have　a　funeral　and　never　revealed　what　she　did　withhis　body。　half　a　century　later　the　whereabouts　of　the　century’s　greatest　astronomer　remainunknown。　for　a　memorial　you　must　look　to　the　sky　and　the　hubble　space　telescope；launched　in　1990　and　named　in　his　honor。

　％％。



9THE　MIGHTY　ATOM

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while　einstein　and　hubble　were　productively　unraveling　the　large…scale　structure　ofthe　cosmos；　others　were　struggling　to　understand　something　closer　to　hand　but　in　its　way　justas　remote：　the　tiny　and　ever…　mysterious　atom。

the　great　caltech　physicist　richard　feynman　once　observed　that　if　you　had　to　reducescientific　history　to　one　important　statement　it　would　be　“all　things　are　made　of　atoms。”　theyare　everywhere　and　they　constitute　every　thing。　look　around　you。　it　is　all　atoms。　not　just　thesolid　things　like　walls　and　tables　and　sofas；　but　the　air　in　between。　and　they　are　there　innumbers　that　you　really　cannot　conceive。

the　basic　working　arrangement　of　atoms　is　the　molecule　（from　the　latin　for　“little　mass”）。

a　molecule　is　simply　two　or　more　atoms　working　together　in　a　more　or　less　stablearrangement：　add　two　atoms　of　hydrogen　to　one　of　oxygen　and　you　have　a　molecule　of　water。

chemists　tend　to　think　in　terms　of　molecules　rather　than　elements　in　much　the　way　thatwriters　tend　to　think　in　terms　of　words　and　not　letters；　so　it　is　molecules　they　count；　and　theseare　numerous　to　say　the　least。　at　sea　level；　at　a　temperature　of　32　degrees　fahrenheit；　onecubic　centimeter　of　air　（that　is；　a　space　about　the　size　of　a　sugar　cube）　will　contain　45　billionbillion　molecules。　and　they　are　in　every　single　cubic　centimeter　you　see　around　you。　thinkhow　many　cubic　centimeters　there　are　in　the　world　outside　your　window—how　many　sugarcubes　it　would　take　to　fill　that　view。　then　think　how　many　it　would　take　to　build　a　universe。

atoms；　in　short；　are　very　abundant。

they　are　also　fantastically　durable。　because　they　are　so　long　lived；　atoms　really　get　around。

every　atom　you　possess　has　almost　certainly　passed　through　several　stars　and　been　part　ofmillions　of　organisms　on　its　way　to　being　you。　we　are　each　so　atomically　numerous　andso　vigorously　recycled　at　death　that　a　significant　number　of　our　atoms—up　to　a　billion　foreach　of　us；　it　has　been　suggested—probably　once　belonged　to　shakespeare。　a　billion　moreeach　came　from　buddha　and　genghis　khan　and　beethoven；　and　any　other　historical　figureyou　care　to　name。　（the　personages　have　to　be　historical；　apparently；　as　it　takes　the　atomssome　decades　to　bee　thoroughly　redistributed；　however　much　you　may　wish　it；　you　arenot　yet　one　with　elvis　presley。）so　we　are　all　reincarnations—though　short…lived　ones。　when　we　die　our　atoms　willdisassemble　and　move　off　to　find　new　uses　elsewhere—as　part　of　a　leaf　or　other　human　beingor　drop　of　dew。　atoms；　however；　go　on　practically　forever。　nobody　actually　knows　how　longan　atom　can　survive；　but　according　to　martin　rees　it　is　probably　about　1035years—a　numberso　big　that　even　i　am　happy　to　express　it　in　notation。

above　all；　atoms　are　tiny—very　tiny　indeed。　half　a　million　of　them　lined　up　shoulder　toshoulder　could　hide　behind　a　human　hair。　on　such　a　scale　an　individual　atom　is　essentiallyimpossible　to　imagine；　but　we　can　of　course　try。

start　with　a　millimeter；　which　is　a　line　this　long：　…。　now　imagine　that　line　divided　into　athousand　equal　widths。　each　of　those　widths　is　a　micron。　this　is　the　scale　of　microorganisms。

a　typical　paramecium；　for　instance；　is　about　two　microns　wide；　0。002　millimeters；　which　isreally　very　small。　if　you　wanted　to　see　with　your　naked　eye　a　paramecium　swimming　in　adrop　of　water；　you　would　have　to　enlarge　the　drop　until　it　was　some　forty　feet　across。

however；　if　you　wanted　to　see　the　atoms　in　the　same　drop；　you　would　have　to　make　the　dropfifteen　miles　across。

atoms；　in　other　words；　exist　on　a　scale　of　minuteness　of　another　order　altogether。　to　getdown　to　the　scale　of　atoms；　you　would　need　to　take　each　one　of　those　micron　slices　and　shaveit　into　ten　thousand　finer　widths。　that’s　the　scale　of　an　atom：　one　ten…millionth　of　amillimeter。　it　is　a　degree　of　slenderness　way　beyond　the　capacity　of　our　imaginations；　but　youcan　get　some　idea　of　the　proportions　if　you　bear　in　mind　that　one　atom　is　to　the　width　of　amillimeter　line　as　the　thickness　of　a　sheet　of　paper　is　to　the　height　of　the　empire　statebuilding。

it　is　of　course　the　abundance　and　extreme　durability　of　atoms　that　makes　them　so　useful；and　the　tininess　that　makes　them　so　hard　to　detect　and　understand。　the　realization　that　atomsare　these　three　things—small；　numerous；　practically　indestructible—and　that　all　things　aremade　from　them　first　occurred　not　to　antoine…laurent　lavoisier；　as　you　might　expect；　or　evento　henry　cavendish　or　humphry　davy；　but　rather　to　a　spare　and　lightly　educated　englishquaker　named　john　dalton；　whom　we　first　encountered　in　the　chapter　on　chemistry。

dalton　was　born　in　1766　on　the　edge　of　the　lake　district　near　cockermouth　to　a　family　ofpoor　but　devout　quaker　weavers。　（four　years　later　the　poet　william　wordsworth　would　alsojoin　the　world　at　cockermouth。）　he　was　an　exceptionally　bright　student—so　very　brightindeed　that　at　the　improbably　youthful　age　of　twelve　he　was　put　in　charge　of　the　local　quakerschool。　this　perhaps　says　as　much　about　the　school　as　about　dalton’s　precocity；　but　perhapsnot：　we　know　from　his　diaries　that　at　about　this　time　he　was　reading　newton’s　principia　in　theoriginal　latin　and　other　works　of　a　similarly　challenging　nature。　at　fifteen；　stillschoolmastering；　he　took　a　job　in　the　nearby　town　of　kendal；　and　a　decade