A Short History of Nearly Everything-第21章

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　given　element。）　there　was　still　a　great　deal　thatwasn’t　known　or　understood。　hydrogen　is　the　most　mon　element　in　the　universe；　and　yetno　one　would　guess　as　much　for　another　thirty　years。　helium；　the　second　most　abundantelement；　had　only　been　found　the　year　before—its　existence　hadn’t　even　been　suspectedbefore　that—and　then　not　on　earth　but　in　the　sun；　where　it　was　found　with　a　spectroscopeduring　a　solar　eclipse；　which　is　why　it　honors　the　greek　sun　god　helios。　it　wouldn’t　beisolated　until　1895。　even　so；　thanks　to　mendeleyev’s　invention；　chemistry　was　now　on　a　firmfooting。

for　most　of　us；　the　periodic　table　is　a　thing　of　beauty　in　the　abstract；　but　for　chemists　itestablished　an　immediate　orderliness　and　clarity　that　can　hardly　be　overstated。　“without　adoubt；　the　periodic　table　of　the　chemical　elements　is　the　most　elegant　organizational　chartever　devised；”　wrote　robert　e。　krebs　in　the　history　and　use　of　our　earth’s　chemicalelements；　and　you　can　find　similar　sentiments　in　virtually　every　history　of　chemistry　in　print。

today　we　have　“120　or　so”　known　elements—ninety…two　naturally　occurring　ones　plus　acouple　of　dozen　that　have　been　created　in　labs。　the　actual　number　is　slightly　contentiousbecause　the　heavy；　synthesized　elements　exist　for　only　millionths　of　seconds　and　chemistssometimes　argue　over　whether　they　have　really　been　detected　or　not。　in　mendeleyev’s　dayjust　sixty…three　elements　were　known；　but　part　of　his　cleverness　was　to　realize　that　theelements　as　then　known　didn’t　make　a　plete　picture；　that　many　pieces　were　missing。　histable　predicted；　with　pleasing　accuracy；　where　new　elements　would　slot　in　when　they　werefound。

no　one　knows；　incidentally；　how　high　the　number　of　elements　might　go；　though　anythingbeyond　168　as　an　atomic　weight　is　considered　“purely　speculative；”　but　what　is　certain　is　thatanything　that　is　found　will　fit　neatly　into　mendeleyev’s　great　scheme。

the　nineteenth　century　held　one　last　great　surprise　for　chemists。　it　began　in　1896　whenhenri　becquerel　in　paris　carelessly　left　a　packet　of　uranium　salts　on　a　wrapped　photographicplate　in　a　drawer。　when　he　took　the　plate　out　some　time　later；　he　was　surprised　to　discoverthat　the　salts　had　burned　an　impression　in　it；　just　as　if　the　plate　had　been　exposed　to　light。　thesalts　were　emitting　rays　of　some　sort。

considering　the　importance　of　what　he　had　found；　becquerel　did　a　very　strange　thing：　heturned　the　matter　over　to　a　graduate　student　for　investigation。　fortunately　the　student　was　arecent　émigré　from　poland　named　marie　curie。　working　with　her　new　husband；　pierre；　curiefound　that　certain　kinds　of　rocks　poured　out　constant　and　extraordinary　amounts　of　energy；yet　without　diminishing　in　size　or　changing　in　any　detectable　way。　what　she　and　her　husbandcouldn’t　know—what　no　one　could　know　until　einstein　explained　things　the　followingdecade—was　that　the　rocks　were　converting　mass　into　energy　in　an　exceedingly　efficient　way。

marie　curie　dubbed　the　effect　“radioactivity。”　in　the　process　of　their　work；　the　curies　alsofound　two　new　elements—polonium；　which　they　named　after　her　native　country；　and　radium。

in　1903　the　curies　and　becquerel　were　jointly　awarded　the　nobel　prize　in　physics。　（mariecurie　would　win　a　second　prize；　in　chemistry；　in　1911；　the　only　person　to　win　in　bothchemistry　and　physics。）at　mcgill　university　in　montreal　the　young　new　zealand–born　ernest　rutherford　becameinterested　in　the　new　radioactive　materials。　with　a　colleague　named　frederick　soddy　hediscovered　that　immense　reserves　of　energy　were　bound　up　in　these　small　amounts　of　matter；and　that　the　radioactive　decay　of　these　reserves　could　account　for　most　of　the　earth’s　warmth。

they　also　discovered　that　radioactive　elements　decayed　into　other　elements—that　one　dayyou　had　an　atom　of　uranium；　say；　and　the　next　you　had　an　atom　of　lead。　this　was　trulyextraordinary。　it　was　alchemy；　pure　and　simple；　no　one　had　ever　imagined　that　such　a　thingcould　happen　naturally　and　spontaneously。

ever　the　pragmatist；　rutherford　was　the　first　to　see　that　there　could　be　a　valuable　practicalapplication　in　this。　he　noticed　that　in　any　sample　of　radioactive　material；　it　always　took　thesame　amount　of　time　for　half　the　sample　to　decay—the　celebrated　half…life—and　that　thissteady；　reliable　rate　of　decay　could　be　used　as　a　kind　of　clock。　by　calculating　backwards　fromhow　much　radiation　a　material　had　now　and　how　swiftly　it　was　decaying；　you　could　work　outits　age。　he　tested　a　piece　of　pitchblende；　the　principal　ore　of　uranium；　and　found　it　to　be　700million　years　old—very　much　older　than　the　age　most　people　were　prepared　to　grant　theearth。

in　the　spring　of　1904；　rutherford　traveled　to　london　to　give　a　lecture　at　the　royalinstitution—the　august　organization　founded　by　count　von　rumford　only　105　years　before；though　that　powdery　and　periwigged　age　now　seemed　a　distant　eon　pared　with　the　roll…your…sleeves…up　robustness　of　the　late　victorians。　rutherford　was　there　to　talk　about　his　newdisintegration　theory　of　radioactivity；　as　part　of　which　he　brought　out　his　piece　of　pitchblende。

tactfully—for　the　aging　kelvin　was　present；　if　not　always　fully　awake—rutherford　notedthat　kelvin　himself　had　suggested　that　the　discovery　of　some　other　source　of　heat　wouldthrow　his　calculations　out。　rutherford　had　found　that　other　source。　thanks　to　radioactivity　theearth　could　be—and　self…evidently　was—much　older　than　the　twenty…four　million　yearskelvin’s　calculations　allowed。

kelvin　beamed　at　rutherford’s　respectful　presentation；　but　was　in　fact　unmoved。　he　neveraccepted　the　revised　figures　and　to　his　dying　day　believed　his　work　on　the　age　of　the　earth　hismost　astute　and　important　contribution　to　science—far　greater　than　his　work　onthermodynamics。

as　　with　　most　　scientific　　revolutions；　　rutherford’s　new　findings　were　not　universallyaccepted。　john　joly　of　dublin　strenuously　insisted　well　into　the　1930s　that　the　earth　was　nomore　than　eighty…nine　million　years　old；　and　was　stopped　only　then　by　his　own　death。　othersbegan　to　worry　that　rutherford　had　now　given　them　too　much　time。　but　even　withradiometric　dating；　as　decay　measurements　became　known；　it　would　be　decades　before　we　gotwithin　a　billion　years　or　so　of　earth’s　actual　age。　science　was　on　the　right　track；　but　still　wayout。

kelvin　died　in　1907。　that　year　also　saw　the　death　of　dmitri　mendeleyev。　like　kelvin；　hisproductive　work　was　far　behind　him；　but　his　declining　years　were　notably　less　serene。　as　heaged；　mendeleyev　became　increasingly　eccentric—he　refused　to　acknowledge　the　existenceof　radiation　or　the　electron　or　anything　else　much　that　was　new—and　difficult。　his　finaldecades　were　spent　mostly　storming　out　of　labs　and　lecture　halls　all　across　europe。　in　1955；element　101　was　named　mendelevium　in　his　honor。　“appropriately；”　notes　paul　strathern；　“itis　an　unstable　element。”

radiation；　of　course；　went　on　and　on；　literally　and　in　ways　nobody　expected。　in　the　early1900s　pierre　curie　began　to　experience　clear　signs　of　radiation　sickness—notably　dull　achesin　his　bones　and　chronic　feelings　of　malaise—which　doubtless　would　have　progressedunpleasantly。　we　shall　never　know　for　certain　because　in　1906　he　was　fatally　run　over　by　acarriage　while　crossing　a　paris　street。

marie　curie　spent　the　rest　of　her　life　working　with　distinction　in　the　field；　helping　to　foundthe　celebrated　radium　institute　of　the　university　of　paris　in　1914。　despite　her　two　nobelprizes；　she　was　never　elected　to　the　academy　of　sciences；　in　large　part　because　after　the　deathof　pierre　she　conducted　an　affair　with　a　married　physicist　that　was　sufficiently　indiscreet　toscandalize　even　the　french—or　at　least　the　old　men　who　ran　the　academy；　which　is　perhapsanother　matter。

for　a　long　time　it　was　assumed　that　anything　so　miraculously　energetic　as　radioactivitymust　be　beneficial。　for　years；　manufacturers　of　toothpaste　and　laxatives　put　radioactivethorium　in　their　products；　and　at　least　until　the　late　1920s　the　glen　springs　hotel　in　the　fingerlakes　region　of　new　york　（and　doubtless　others　as　well）　featured　with　pride　the　therapeuticeffects　of　its　“radioactive　mineral　springs。”　radioactivity　wasn’t　banned　in　consumerproducts　until　1938。　by　this　time　it　was　much　too　late　for　madame　curie；　who　died　ofleukemia　in　1934。　radiation；　in　fact；　is　so　pernicious　and　long　lasting　that　even　now　herpapers　from　the　1890s—even　her　cookbooks—are　too　dangerous　to　handle。　her　lab　books　arekept　in　lead…lined　boxes；　and　those　who　wish　to　see　them　must　don　protective　clothing。

thanks　to　the　devoted　and　unwittingly　high…risk　work　of　the　first　atomic　scientists；　by　theearly　years　of　the　twentieth　century　it　was　being　clear　that　earth　was　unquestionablyvenerable；　though　another　half　century　of　science　would　have　to　be　done　before　anyone　couldconfidently　say　quite　how　venerable。　science；　meanwhile；　was　about　to　get　a　new　age　of　itsown—the　atomic　one。

part　　iii　　　a　new　age　dawnsa　physicist　is　the　atoms’　way　of　thinking　about　atoms。

…anonymous

　。。



8EINSTEIN’S　UNIVERSEAS

；小；说；〃；网
the　nineteenth　century　drew　to　a　close；　scientists　could　reflect　with　satisfaction　thatthey　had　pinned　down　most　of　the　mysteries　of　the　physical　world：　electricity；　magnetism；gases；　optics；　acousti