【英语翻译根据广义相对论,引力场将使时空弯曲.当恒星的体积很-查字典问答网
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  【英语翻译根据广义相对论,引力场将使时空弯曲.当恒星的体积很大时,它的引力场对时空几乎没什么影响,从恒星表面上某一点发的光可以朝任何方向沿直线射出.而恒星的半径越小,它对周围的】

  英语翻译

  根据广义相对论,引力场将使时空弯曲.当恒星的体积很大时,它的引力场对时空几乎没什么影响,从恒星表面上某一点发的光可以朝任何方向沿直线射出.而恒星的半径越小,它对周围的时空弯曲作用就越大,朝某些角度发出的光就将沿弯曲空间返回恒星表面.

  等恒星的半径小到一特定值(天文学上叫“史瓦西半径”)时,就连垂直表面发射的光都被捕获了.到这时,恒星就变成了黑洞.说它“黑”,是指它就像宇宙中的无底洞,任何物质一旦掉进去,“似乎”就再不能逃出.实际上黑洞真正是“隐形”的.那么,黑洞是怎样形成的呢?其实,跟白矮星和中子星一样,黑洞很可能也是由恒星演化而来的.当一颗恒星衰老时,它的热核反应已经耗尽了中心的燃料(氢),由中心产生的能量已经不多了.这样,它再也没有足够的力量来承担起外壳巨大的重量.所以在外壳的重压之下,核心开始坍缩,直到最后形成体积小、密度大的星体,重新有能力与压力平衡.

  质量小一些的恒星主要演化成白矮星,质量比较大的恒星则有可能形成中子星.而根据科学家的计算,中子星的总质量不能大于三倍太阳的质量.如果超过了这个值,那么将再没有什么力能与自身重力相抗衡了,从而引发另一次大坍缩.

  这次,根据科学家的猜想,物质将不可阻挡地向着中心点进军,直至成为一个体积趋于零、密度趋向无限大的“点”.而当它的半径一旦收缩到一定程度(史瓦西半径),asImentionbefore,巨大的引力就使得即使光也无法向外射出,从而切断了恒星与外界的一切联系——“黑洞”诞生了.

  与别的天体相比,黑洞是显得太特殊了.例如,黑洞有“隐身术”,人们无法直接观察到它,连科学家都只能对它内部结构提出各种猜想.那么,黑洞是怎么把自己隐藏起来的呢

1回答
2019-04-09 16:50
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冯雅丽

  Actually,aresamewiththewhitedwarfstarsandtheneutronstars,theblackholeareformedfromthegravitationalcollapseofstars,usuallyhavingagreat,massive,core.Whenstarsaregettingsenile,theirthermonuclearreactionshaveexhaustedthecentralfuel(Hydrogen).Thus,theydonothaveenoughpowertoundertakethehugeweightoftheircovering.Therefore,thegravitationalpullthecoreofthestarbegincollapse,untiltheyreformintothestarofsmallmassandhighdensity.Thestararecreatedwhenhuge,gigantic;gascloudsbindtogetherduetoattractiveforcesandformahotcore,combinedfromalltheenergyofthetwogasclouds.Thisenergyproducedissogreatwhenitfirstcollides,thatanuclearreactionoccursandthegaseswithinthestarstarttoburncontinuously.²TheHydrogenisthedominantgasconsumedinastar.Theequilibriumachievedthestarinordertoavoidcollapsingatthispoint.Thegravitationalpullfromthecoreofthestarisequaltothegravitationalpullofthegasesformingatypeoforbit.²however;thestarcouldgetintovariousstageswhenthisequalityisdestroyed.ThestarsofsmallinmasswillevolutionastheWhiteDwarf.Ifthestarsaretohavealargermass,thenitmaypossiblybeaSupernova.Ablackholeisoneofthelastoptionsthatastarmaytake.Ifthecoreofastarissomassive(approximately6-8solarmasses;onesolarmassbeingequaltothesun’smass)²thenitismostlikelythatwhenthestar’sgasesarealmostconsumedthosegaseswillcollapseinward,forcedintothecorebythegravitationalforcelaiduponthem.

  Comparetootherwondersinthegalaxy,blackholesareverymysteriousandspecial,becauseoftheirabilitytomakethemselvesinvisible,thuspeopleareunabletoobservethem.Evenscientistsareonlyabletosurmisewhattheirinternalstructuresare.Inthatway,howdoblackholeshidethemselves?Theansweriswarpedspaceandtime.Accordingtotheory,lightspreadalongastraightline,however,thetimeandspacewillbebendingunderthegravitationalfield.Inthatarea,lightstilltravelbetweenanytwopoints,butthepathwayofthelightisnolongerhorizontal,insteaditbecomesbended.Inotherword,lightwanttogoinastraightline,yetstronggravitationalforcesarepullingthelighttobenditselffromtheoriginaldirection.

  Accordingtothegeneraltheoryofrelativity,thegravitationalfieldwillcausecausethespaceandtimetobebended.Whenthestar’svolumeisreallybig,itsgravitationalfieldnearlydoesnotinfluencetothespaceandtime.Thelightcantravelalongastraightlineinanydirection.Incontract,thesmallerradiusesofthestarwillsufferhugegravitational.Thegravitationalpullthelightalongthecurvedtrackreturnstothesurfaceofstars.Whenthestar’sradiislightasacharacteristicradius(inastronomyiscalledSchwarzschildradiusasaspecificvalue,sometimeshistoricallyreferredtoasthegravitationalradius),theverticalsuperficiallaunchlightwillbecaught.Atthistime,thestarsbecomeblackholes.Theyarelikelythebottomlesspitsintheuniverse,oncefallingintoseemnoabletoescape.Thehugegravitationalthelightunableoutwardtoobject,thushascutofftherelationbetweenstarandoutside.Therefore,theblackholeisbecominginvisible.³

2019-04-09 16:53:48

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