作者君在作品相关中其实已经解释过这个问题。
不过仍然有人质疑——“你说得太含糊了”,“火星轨道的变化比你想象要大得多!”
那好吧,既然作者君的简单解释不够有力,那咱们就看看严肃的东西,反正这本书写到现在,嚷嚷着本书bug一大堆,用初高中物理在书中挑刺的人也不少。
以下是文章内容:
long-tertegrationsandstabilityofparyorbitsoursorsyste
abstract
&nbsepresenttheresultsofverylong-ternuricaltegrationsofparyorbitalotionsover109-yrti-spanscludgallnepsaquickspectionofournuricaldatashowsthattheparyotion,atleastoursipledynaicalodel,seestobequitestableevenoverthisverylongti-spanacloserlookatthelowest-frequencyosciltionsgalow-passfiltershowsthepotentiallydiffivecharacterofterrestrialparyotion,especiallythatofrcurythebehaviouroftheeentricityofrcuryourtegrationsisqualitativelysiirtotheresultsfrojacquesskar'ssecurperturbationtheory(egeax~035over~±4gyr)however,therearenoapparentsecurcreasesofeentricityorclationanyorbitalelentsoftheps,&nbshichayberevealedbystilllonger-ternuricaltegrations&nbsehavealsoperfordaupleoftrialtegrationscludgotionsoftheouterfivepsoverthedurationof±5x1010yrtheresultdicatesthatthethreeajorresonancestheneptune–plutosystehavebeenataedoverthe1011-yrti-span
1troduction
11defitionoftheproble
thequestionofthestabilityofoursorsystehasbeendebatedoverseveralhundredyears,scetheeraofnewtontheproblehasattractedanyfaoatheaticiansovertheyearsandhaspyedacentralrolethedevelopntofnon-leardynaicsandchaostheoryhowever,&nbsedonotyethaveadefiteanswertothequestionof&nbshetheroursorsysteisstableornotthisispartlyaresultofthefactthatthedefitionoftheter‘stability’isvague&nbshenitisedretiontotheprobleofparyotionthesorsysteactuallyitisnoteasytogiveaclear,rigoroandphysicallyangfuldefitionofthestabilityofoursorsyste
aonganydefitionsofstability,here&nbseadoptthehilldefition(gdan1993):actuallythisisnotadefitionofstability,butofstability&nbsedefeasysteasbegunstable&nbshenacloseenunterourssowherethesyste,startgfroacertaitialnfiguration(chabers,&nbsetherill&apapboss1996ito&apaptanikawa1999)asysteisdefedasexperiencgacloseenunter&nbshenobodiesapproachoneanother&nbsithanareaofthergerhillradiotherwisethesysteisdefedasbegstablehenceforward&nbsestatethatourparysysteisdynaicallystableifnocloseenunterhappensdurgtheageofoursorsyste,about±5gyrcidentally,thisdefitionayberepcedbyone&nbshichanourrenceofanyorbitalcrossgbeeeneitherofapairofpstakespcethisisbecae&nbseknowfroexperiencethatanorbitalcrossgisverylikelytoleadtoacloseenunterparyandproarysystes(yoshaga,kokubo&apapako1999)ofursethisstatentcannotbesiplyappliedtosystes&nbsithstableorbitalresonancessuchastheneptune–plutosyste
12previostudiesandaisofthisresearch
additiontothevaguenessofthenceptofstability,thepsoursorsysteshowacharactertypicalofdynaicalchaos(ssan&apap&nbsisdo1988,1992)thecaeofthischaoticbehaviourisnowpartlyunderstoodasbegaresultofresonanceoverppg(urray&apapholan1999lecar,frankl&apapholan2001)however,it&nbsouldrequiretegratgoveranensebleofparysystescludgallnepsforaperiodvergseveral10gyrtothoroughlyunderstandthelong-terevolutionofparyorbits,scechaoticdynaicalsystesarecharacterizedbytheirstrongdependenceonitialnditions
frothatpotofview,anyofthepreviolong-ternuricaltegrationscludedonlytheouterfiveps(ssan&apap&nbsisdo1988koshita&apapnakai1996)thisisbecaetheorbitalperiodsoftheouterpsaresouchlongerthanthoseofthenerfourpsthatitisucheasiertofollowthesysteforagiventegrationperiodatpresent,thelongestnuricaltegrationspublishedjournalsarethoseofduncan&apaplissauer(1998)althoughtheiratarget&nbsastheeffectofpost-a-sequencesorasslossonthestabilityofparyorbits,theyperfordanytegrationsvergupto~1011yroftheorbitalotionsofthefourjovianpstheitialorbitalelentsandassesofpsarethesaasthoseofoursorsysteduncan&apaplissauer'spaper,buttheydecreasetheassofthesungraduallytheirnuricalexperintsthisisbecaetheynsidertheeffectofpost-a-sequencesorasslossthepapernsequently,theyfoundthatthecrossgti-scaleofparyorbits,&nbshichcanbeatypicaldicatorofthestabilityti-scale,isquitesensitivetotherateofassdecreaseofthesun&nbshentheassofthesunisclosetoitspresentvalue,thejovianpsreastableover1010yr,orperhapslongerduncan&apaplissaueralsoperfordfoursiirexperintsontheorbitalotionofsevenps(ventoneptune),&nbshichveraspanof~109yrtheirexperintsonthesevenpsarenotyetprehensive,butitseesthattheterrestrialpsalsoreastabledurgthetegrationperiod,atagalostregurosciltions
ontheotherhand,hisauratesei-analyticalsecurperturbationtheory(skar1988),skarfdsthatrgeandirregurvariationscanappeartheeentricitiesandclationsoftheterrestrialps,especiallyofrcuryandarsonati-scaleofseveral109yr(skar1996)theresultsofskar'ssecurperturbationtheoryshouldbenfirdandvestigatedbyfullynuricaltegrations
thispaper&nbsepresentpreliaryresultsofsixlong-ternuricaltegrationsonallneparyorbits,vergaspanofseveral109yr,andofoothertegrationsvergaspanof±5x1010yrthetotalepsedtiforalltegrationsisorethan5yr,gseveraldedicatedpcsand&nbsorkstationsoneofthefundantalnclionsofourlong-tertegrationsisthatsorsysteparyotionseestobestabletersofthehillstabilityntionedabove,atleastoverati-spanof±4gyractually,ournuricaltegrationsthesyste&nbsasfarorestablethan&nbshatisdefedbythehillstabilitycriterion:notonlydidnocloseenunterhappendurgthetegrationperiod,butalsoalltheparyorbitalelentshavebeennfedanarrowregionbothtiandfrequencydoa,thoughparyotionsarestochasticscethepurposeofthispaperistoexhibitandoverviewtheresultsofourlong-ternuricaltegrations,&nbseshowtypicalexaplefiguresasevidenceoftheverylong-terstabilityofsorsysteparyotionforreaders&nbshohaveorespecificanddeeperterestsournuricalresults,&nbsehaveprepareda&nbsebpage(aess),&nbshere&nbseshowraworbitalelents,theirlow-passfilteredresults,variationofdeunayelentsandangurontudeficit,andresultsofoursipleti–frequencyanalysisonallofourtegrations
section2&nbsebrieflyexpourdynaicalodel,nuricalthodanditialnditionsedourtegrationssection3isdevotedtoadescriptionofthequickresultsofthenuricaltegrationsverylong-terstabilityofsorsysteparyotionisapparentbothparypositionsandorbitalelentsaroughestiationofnuricalerrorsisalsogivensection4goesontoadiscsionofthelongest-tervariationofparyorbitsgalow-passfilterandcludesadiscsionofangurontudeficitsection5,&nbsepresentasetofnuricaltegrationsfortheouterfivepsthatspans±5x1010yrsection6&nbsealsodiscsthelong-terstabilityoftheparyotionanditspossiblecae
2descriptionofthenuricaltegrations
(本部分涉及比较复杂的积分计算,作者君就不贴上来了,贴上来了起点也不一定能成功显示。)
23nuricalthod
&nbseutilizeasend-order&nbsisdo–holansyplecticapasourategrationthod(wisdo&apapholan1991koshita,yoshida&apapnakai1991)&nbsithaspecialstart-upproceduretoreducethetruncationerrorofanglevariables,‘warstart’(saha&apaptreae1992,1994)
thestepsizeforthenuricaltegrationsis8dthroughoutalltegrationsoftheneps(n±1,2,3),&nbshichisabout1/11oftheorbitalperiodofthenerostp(rcury)asforthedeterationofstepsize,&nbsepartlyfollowtheprevionuricaltegrationofallnepsssan&apap&nbsisdo(1988,72d)andsaha&apaptreae(1994,225/32d)&nbseroundedthedecialpartofthetheirstepsizesto8toakethestepsizeaultipleof2ordertoreducetheauutionofround-offerrortheputationprocessesretiontothis,&nbsisdo&apapholan(1991)perfordnuricaltegrationsoftheouterfiveparyorbitsgthesyplecticap&nbsithastepsizeof400d,1/1083oftheorbitalperiodofjupitertheirresultseestobeaurateenough,&nbshichpartlyjtifiesourthodofdetergthestepsizehowever,scetheeentricityofjupiter(~005)isuchsallerthanthatofrcury(~02),&nbseneedsocare&nbshen&nbseparethesetegrationssiplytersofstepsizes
thetegrationoftheouterfiveps(f±),&nbsefixedthestepsizeat400d
&nbseadoptgas'fandgfunctionsthesyplecticaptogether&nbsiththethird-orderhalleythod(danby1992)asasolverforkeplerequationsthenuberofaxiuiterations&nbsesethalley'sthodis15,buttheyneverreachedtheaxiuanyofourtegrations
thetervalofthedataoutputis200000d(~547yr)forthecalcutionsofallneps(n±1,2,3),andabout8000000d(~21903yr)forthetegrationoftheouterfiveps(f±)
althoughnooutputfilterg&nbsasdone&nbshenthenuricaltegrations&nbsereprocess,&nbseappliedalow-passfiltertotheraworbitaldataafter&nbsehadpletedallthecalcutionsseesection41fororedetail
24errorestiation
241retiveerrorstotalenergyandangurontu
aordgtooneofthebasicpropertiesofsyplectictegrators,&nbshichnservethephysicallynservativequantities&nbsell(totalorbitalenergyandangurontu),ourlong-ternuricaltegrationsseetohavebeenperford&nbsithverysallerrorstheaveragedretiveerrorsoftotalenergy(~10?9)andoftotalangurontu(~10?11)havereaednearlynstantthroughoutthetegrationperiod(fig1)thespecialstartupprocedure,&nbsarstart,&nbsouldhavereducedtheaveragedretiveerrortotalenergybyaboutoneorderofagnitudeorore
retivenuricalerrorofthetotalangurontuδa/a0andthetotalenergyδe/e0ournuricaltegrationsn±1,2,3,&nbshereδeandδaaretheabsolutechangeofthetotalenergyandtotalangurontu,respectively,ande0anda0aretheiritialvaluesthehorizontalunitisgyr
notethatdifferentoperatgsystes,differentatheaticallibraries,anddifferenthardwarearchitecturesresultdifferentnuricalerrors,throughthevariationsround-offerrorhandlgandnuricalalgorithstheupperpaneloffig1,&nbsecanregnizethissituationthesecurnuricalerrorthetotalangurontu,&nbshichshouldberigorolypreserveduptoache-eprecision
242errorparylongitudes
scethesyplecticapspreservetotalenergyandtotalangurontuofn-bodydynaicalsystesherently&nbsell,thedegreeoftheirpreservationaynotbeagoodasureoftheauracyofnuricaltegrations,especiallyasaasureofthepositionalerrorofps,ietheerrorparylongitudestoestiatethenuricalerrortheparylongitudes,&nbseperfordthefollogprocedures&nbseparedtheresultofouralong-tertegrations&nbsithsotesttegrations,&nbshichspanuchshorterperiodsbut&nbsithuchhigherauracythantheategrationsforthispurpose,&nbseperfordauchoreauratetegration&nbsithastepsizeof0125d(1/64oftheategrations)spanng3x105yr,startg&nbsiththesaitialnditionsasthen?1tegration&nbsensiderthatthistesttegrationprovides&nbsitha‘pseudo-true’solutionofparyorbitalevolutionnext,&nbseparethetesttegration&nbsiththeategration,n?1fortheperiodof3x105yr,&nbseseeadifferenceananoaliesoftheearthbeeentheotegrationsof~052°(thecaseofthen?1tegration)thisdifferencecanbeextrapotedtothevalue~8700°,about25rotationsofearthafter5gyr,scetheerroroflongitudescreaseslearly&nbsithtithesyplecticapsiirly,thelongitudeerrorofplutocanbeestiatedas~12°thisvalueforplutoisuchbetterthantheresultkoshita&apapnakai(1996)&nbsherethedifferenceisestiatedas~60°
3nuricalresults–ignceattherawdata
thissection&nbsebrieflyreviewthelong-terstabilityofparyorbitalotionthroughsosnapshotsofrawnuricaldatatheorbitalotionofpsdicateslong-terstabilityallofournuricaltegrations:noorbitalcrossgsnorcloseenuntersbeeenanypairofpstookpce
31generaldescriptionofthestabilityofparyorbits
first,&nbsebrieflylookatthegeneralcharacterofthelong-terstabilityofparyorbitsourterestherefocesparticurlyonthenerfourterrestrialpsfor&nbshichtheorbitalti-scalesareuchshorterthanthoseoftheouterfivepsas&nbsecanseeclearlyfrothepnarorbitalnfigurationsshownfigs2and3,orbitalpositionsoftheterrestrialpsdifferlittlebeeentheitialandfalpartofeachnuricaltegration,&nbshichspansseveralgyrthesolidlesdenotgthepresentorbitsofthepsliealost&nbsiththeswarofdotseventhefalpartoftegrations(b)and(d)thisdicatesthatthroughouttheentiretegrationperiodthealostregurvariationsofparyorbitalotionreanearlythesaastheyareatpresent
verticalviewofthefournerparyorbits(frothez-axisdirection)attheitialandfalpartsofthetegrationsn±1theaxesunitsareauthexy-pneissettothevariantpneofsorsystetotalangurontu(a)theitialpartofn+1(t=0to00547x109yr)(b)thefalpartofn+1(t=49339x108to49886x109yr)(c)theitialpartofn?1(t=0to?00547x109yr)(d)thefalpartofn?1(t=?39180x109to?39727x109yr)eachpanel,atotalof23684potsareplotted&nbsithantervalofabout2190yrover547x107yrsolidleseachpaneldenotethepresentorbitsofthefourterrestrialps(takenfrode245)
thevariationofeentricitiesandorbitalclationsforthenerfourpstheitialandfalpartofthetegrationn+1isshownfig4asex