爱因斯坦的生死方程式.docx
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爱因斯坦的生死方程式.docx
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爱因斯坦的生死方程式
In1939,ontheeveoftheSecondWorldWar,
AlbertEinsteinwrotealettertothe
AmericanPresident,FranklinRoosevelt.
Sir,theelementUranium
maybeturnedintoanewand
importantsourceofenergy
intheimmediatefuture.
Certainaspectsofthesituationwhichhas
arisenseemtocallforwatchfulness
and,ifnecessary,quickactionon
thepartoftheadministration.
Extremelypowerfulbombsofa
newtypemaythusbeconstructed.
Theletterwasaboutanapplication
ofEinstein'sfamousequation,
e=mc².
AndhisfearthattheNaziscoulduse
ittobuildanatomicbomb.
Hislettersetoffachainofeventswhichledto
thedestructionofHiroshimaandNagasaki.
AlbertEinsteinwouldlaterdescribewriting
thisletterastheonemistakeofhislife.
Thisisthestoryofhisfamousequation.
Andhowe=mc²changedhistoryandEinsteinforever.
OntheeveofSecondWorldWarAlbertEinstein,
themostfamousscientistintheworld,
wasonholidaybythecoastoutsideNewYork.
Hewasaninstinctivepacifist
whohadfledNaziGermany,
andhehadhopedtoturnhisback
ontheviolenceinEurope,
andcontinuehisworkinpeace.
Buthissummerwasinterruptedby
avisitorwhohadalsofledtheNazis.
ThecallerwasLeoSzilard,anotherbrilliantscientist
andanoldfriendofEinstein'sfromEurope.
Szilard.
HerrProfessor,thereissomethingwemustdo.
Comein.
LeoSzilardhadcometopersuadehisoldfriend
thattheworldwasthreatened
byanewweapon.
HisaimwastoconvinceEinstein
thatsomethinghadtobedone.
Cookie?
HerrProfessor,Ineedyourhelp.
Why?
Areyouontherunfromthepolice?
Iwishitwasthatsimple.Iwant
youtohelpmecomposealetter.
It'salongwaytocomeforhelp
withyourcorrespondence.
Notthiscorrespondence.I'venever
writtenaletterlikethisbefore.
I'mnotevensurewhatIshouldsay.
Whoistheletterto?
Roosevelt.
PresidentRoosevelt.Areyouoffering
advice,oradmonition?
Awarning.IwanttowarnRoosevelt
abouttheGermanbomb.
TheGermanshavemanybombs.
Notonelikethis.Atleast,notyet.
It'sanatomicbomb,theGermansare
goingtobeabletobuildanatomicbomb.
Andiftheyaredoingit,thensomustwe.
ThismeetingwouldonedaycometohauntEinstein.
BecauseLeoSzilardhadcometoexplain
thattheNaziprojecthefearedsomuch
wasanapplicationofsomething
Einsteinhimselfhaddiscovered,
theequatione=mc².
E=mc²isthesymbolofEinstein'sgenius.
It'sanequationthatsumsuponeofthe
mostpowerfultruthsabouttheuniverse.
Itcombinestwoideas,which
untilEinsteincamealong,
noonehadeverdreamedcouldbe
connectedinsuchapowerfulway.
TheideaofMass.
Andtheideaofenergy.
Ifyouthinkaboutenergyandmass
itisnotatallobviousthatthey're
anythinglikethesamething.
Imeanenergyissomethingthatmovingobjectshave,
andmassissomethingthateveryobjectpossesses.
Soreallyit'saboldsteptotryandlinktheminanyway,
letaloneinabeautifulwaythatEinsteindid.
Einstein'sgreatinsightwasthatenergy,the
thingthatenablesanobjecttomove,
andmass,essentiallyanobjectsweight,
arenotdifferent,theyareinfactthesamething.
Einsteinreallyfoundthatenergyand
massaretwosidesofthesamecoin.
They'realmostthesamething,somassin
asenseisenergywaitingtobeliberated.
Inotherwords,accordingtoEinstein,
masscouldbetransformedintoenergy.
Andenergyintomass.
ButEinstein'sequationwentevenfurther.
Itgaveanexactvaluetotheamountof
energycontainedwithinanygivenmass.
EnergyequalsmasstimesC-
thespeedoflight,squared,
anumberthatisabsolutelyhuge.
ThisisEinstein'sfamousequation:
e,energy
equalsm,mass,timescsquared,thespeedoflightsquared.
Inmetrespersecond:
eightyninethousand,eighthundredand
seventyfivemillionmillion,hugenumber.
Thatmeansyougetanawfullotofenergy
foranextremelytinyamountofmass.
Theimplicationsofthisneatequationwerevast.
Wellitmeansthatthere'senough
energyinaglassofwater
topoweracitylikeLondonforaweek.
Hiddenwithineveryobjectaround
usisahugestoreofenergy.
Einsteinpublishede=mc²in1905.
Anditchangedtheworld.
Itwasn'tlongbeforee=mc²solvedone
ofthegreatmysteriesoflifeonearth.
Whatreallypowersthesun?
Forgenerationsthishadbaffledscientists.
Becauseifthesunjustburnedlikeahugebonfire,
thecalculationsshoweditshouldhave
diedoutmillionsofyearsago.
ButEinstein'sequationexplained
whatwaspoweringthesun.
Inthesun'score,masswasconstantly
beingconvertedintoenergy.
Aprocessthatcanbesustainedforbillionsofyears.
Tinyparticlesweresmashingtogether,
andthemasslostinthisreaction
wastransformedintoenergy.
Andsoonpeoplebegantothink,
ife=mc²canpowerthesun,
couldweuseittogeneratepoweronearth?
Couldwereleasetheenergyinside
atomsforourownpurposes?
Withinyears,talkofgettingenergyoutofthe
atombegantogripthepopularimagination.
Andatascientificconferencein1935,
Einsteinwasaskedwhetherhethought
theatomwouldeveryielditsenergy.
Hisanswerwastogodowninscientifichistory.
Thelikelihoodoftransformingmatterintoenergy
issomethingakintoshootingbirdsinthedark
inacountryinwhichthereareveryfewbirds.
Inotherwords,Einsteinbelieved
gettingenergyoutoftheatom
wasjustnotpractical.
Itwouldtakeanalmostincalculableamountofenergy
toreleaseenergyevenfromevenasinglemolecule.
Einsteinwassodismissivebecause
itwasbecomingclear
thattoreleaseallthatenergy
scientistswouldhavetofindanefficient
wayofbreakingtheatomapart.
Andhoweverhardtheytried,
italwaystookmoreenergytosmash
anatomthanwasreleased.
Kindatough,huh?
Kindoftough,yes.
Butotherswerelessdismissive.
In1933HitlercametopowerinGermany.
Germanywasoneofthegreatcentresofphysics.
Someofitsscientistswereonly
toowillingtoworkwithNazis.
AndtheNaziwarmachinewaseagerto
achievewhatEinsteinhadsaidwasimpossible,
toreleaseenergyfromthe
atom,andcreateabomb.
UnlikeEinstein,LeoSzilardfearedthat
energycouldbereleasedfromtheatom
accordingtoe=mc²,andthen
usedtoconstructabomb.
Andthatfearhadtakenhimtosee
EinsteinthatsummerinLongIsland.
ThewarinEuropeisgoingtohappen.Hitlerhas
plannedforit.Andhehasbuiltuphisarms.
Andonceherealisesitspower,hewill
nothesitatetoconstructanatomicbomb.
Butthatwouldtakeyears.
Whyyears?
Tobuildsuchabombthereaction
wouldhavetotakeplace
inmultiplemillionsofatomssimultaneously.
Maybenotsimultaneously.
Ithinkmaybethereisanother
waythatmightbeachieved.
Szilardwasspeakingwithsuchconfidence
becauseheknewsomethingEinsteindidnot.
LeoSzilardhadworkedout
howtomakee=mc²intoabomb.
In1920,ayoungLeoSzilard
hadgonetostudyinBerlin.
TherehewitnessedtheriseoftheNazis.
Szilardbecameworriedbywhatthis
mightmeanforscienceandfortheworld.
Szilardwasreallyscaredbecausehe
hadseentheNaziterrorfirsthand.
Hewarnedhiscolleaguesandthenhe
himselfleftshortlyafterHitlertookpower.
Hewastryingtodrawasmanyfriends
ashecouldoutofNaziGermany,
hesawhowtheterrorwasspreading.
ButmanybrilliantphysicistsremainedinGermany,
andSzilardwasfearfulit
wasonlyamatteroftime
beforesomeonewouldfindaway
ofharnessingthepowerofe=mc²
andmakeabomb.
Infact,thefirststephadalready
inadvertentlybeentaken,
scientistshadidentifiedthetypeofsubstance
theymightneedtoturnmassintoenergy.
Yesradioactivityisalready
atworkinmedicalfields...
Radioactiveiodine.
soifyouwilllistenandwatchatthe
sametimewhenweheartheclicks.
Radioactivityise=mc²inaction.
UnstableelementslikeRadiumand
Uraniumcontinuallybreakdown
intoeversmallerelementsin
ordertobecomemorestable.
Whatisactuallyhappeningisthattinyamounts
ofmassfromtheheartofanunstableatom
arespontaneouslyreleasedintheformofenergy,
whichiscarriedawayasradiation.
Butfindingtherighttypeofsubstance
toreleaseenergyaccordingtoe=mc²
wasonlyhalftheanswer.
Thisscintillatingcharacterisveryunstable,and
asaconsequencesheradiatesenergy.
Wecallherradioactive.
Naturalradioactivitywasoriginally
thoughttobepotentiallyveryuseful.
Butthemorethatwasunderstoodaboutit,
itwasrealisedthatthisparticularform
ofradioactivitywhilstproducingheat
wasnotespeciallyefficient.
Theamountofheatgivenoutwasrathersmall.
Thisisradioactiveiodine.
I'mnowgoingtodrinkthis.
Naturalradioactivitywassimplyfartoo
gentleforgeneratingrealpower.
Soscientistsbegantodevelopwaysofimprovinguponnature.
InGermany,inBritainandinAmerica
machineswerebuilttoachievenuclearfission,
thesplittingopenoftheatomicnucleus.
Manyhopedthismightrelease
thevastamountsofenergy
potentiallyhiddenwithintheatom.
Initiallyhopeswerehigh,butagain
andagaintheyhitEinstein'sparadox.
Theyalwayshadtoputinfarmore
energythantheyevergotout.
Thelikelihoodoftransformingmatterintoenergy
issomethingakintoshootingbirdsinthedark
inacountryinwhichthereareonlyveryfewbirds.
ItlookedasthoughEinsteinhadbeenrightafterall.
e=mc²wassimplyatheoreticalinsight,
notapracticalsolutiontogenerating
vastamountsofenergy.
ButthenEinstein'sfriend,Leo
Szilardhadhisfirstbrainwave.
Ithappeneddayin1933.
Hesuddenlyrealisedeveryonehad
beengoingaboutitthewro
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