首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Black holes. They act like huge drains in the universe. Frightening? Fascinating? Or just fantasy? The very concept of black hol
Black holes. They act like huge drains in the universe. Frightening? Fascinating? Or just fantasy? The very concept of black hol
admin
2010-06-30
81
问题
Black holes. They act like huge drains in the universe. Frightening? Fascinating? Or just fantasy? The very concept of black holes confuses our common sense notions of matter, time, and space. The theory that black holes can, and probably do, exist in space doesn’ t only concern scientists and astronomers.
【61】
For if the theory is valid, we must question all our basic physical laws and, indeed, our "normal" experience of the physical world around us.
What is a black hole? Well, it’s difficult to answer this question, since the terms we would normally use to describe a scientific phenomenon are inadequate here. 【62】
Astronomers and scientists think that a black hole is a region of space (not a thing) into which matter has fallen and from which nothing can escape--not even light.
So we can’ t see a black hole. A black hole exerts a strong gravitational pull and yet it has no matter. It is only space---or so we think. How can this happen?
The theory is that some stars explode when their density increases to a particular point; they "collapse" and sometimes a supernova occurs. The collapse of a star may produce a "White Dwarf" or a "neutron star’--a star whose matter is so dense that it continually shrinks by the force of its own gravity. But if the star is very large (much bigger than our sun) this process of shrinking may be so intense that a black hole results. 【63】
Imagine the earth reduced to the size of a marble, but still having the same mass and a stronger gravitational pull, and you have some idea of the force of a black hole.
Any matter near the black hole is sucked in. It is impossible to say what happens inside a black hole.
Our space and time laws don’ t seem to apply to objects in the area of a black hole. Einstein’ s relativity theory is the only one that can explain such phenomena. Einstein claimed that matter and energy are interchangeable, so that there is no "absolute" time and space. There are no constants at all, and measurements of time and space depend on the position of the observer --they are relative. 【64】
We do not yet fully understand the implications of relativity theory; but it is interesting that Einstein’ s theory provided a basis for their existence.
It is only recently that astronomers have begun specific research into black holes.
The most convincing evidence of black holes comes from research into binary star systems. In some binary systems, astronomers have shown that there is an invisible companion star, a "partner" to the one which we can see in the sky. There is one star, called by its catalogue number HDE 226868,which must have a partner. This partner star, it seems, has a mass ten or twenty times greater than the sun--yet we can’t see it. Matter from HDE 226868 is being dragged towards this companion star. Could this invisible star, which exerts such a great force, be a black hole? Astronomers have evidence of a few other stars too, which might have black holes as companions.
The story of black holes is just beginning. Speculations about them are endless. There might be a massive black hole at the center of our galaxy swallowing up stars at a very rapid rate. Mankind may one day meet this fate. On the other hand, scientists have suggested that very advanced technology could one day harness the energy of black holes for man’ s use on earth. There are also suggestions that black holes could be used to create bombs in the future, by amplifying radio waves sent up to them. These speculations sound like science fiction. But the theory of black holes in space is accepted by many serious scientists and astronomers. 【65】
They show us a world that operates in a totally different way from our own and they question our most basic experience of space and time.
【63】
选项
答案
试想,如果地球体积缩小到如一块大理石,而其质量不变并且吸引力更大,你就会对黑洞的力量有了一点认识。
解析
转载请注明原文地址:https://kaotiyun.com/show/p7Pd777K
本试题收录于:
公共英语四级笔试题库公共英语(PETS)分类
0
公共英语四级笔试
公共英语(PETS)
相关试题推荐
IfyouarebuyingapropertyinFrance,whetherforapermanentoraholidayhome,itisimportanttoopenaFrenchbankaccount
IfyouarebuyingapropertyinFrance,whetherforapermanentoraholidayhome,itisimportanttoopenaFrenchbankaccount
Somepeopleclaimthattelevisionisgoodforchildrenbecauseitgetschildrenclevererbywatchingit,whileothersthinkthat
Beforeabigexam,asoundnight’ssleepwilldoyoubetterthanporingovertextbooks.That,atleast,isthefolkwisdom.And
Opinionpollsarenowbeginningtoshowthat,whoeveristoblameandwhateverhappensfromnowon,highunemploymentisprobabl
RecentsurveysshowthatJapaneseyouthhavebecomea"MeGeneration"thatrejectstraditionalvalues."Around1980manyJap
A=HydropowerB=NuclearpowerC=SolarpowerD=WindpowerWhichpower(power’s)...wasdevelopedtoprovideelectricity
WhichofthefollowingappliestothemanagementofhumanresourcesinAmericancompanies?Whatisthemainideaofthepassage
Afindinginrecentyearsshowsthatmencannotmanufacturebloodasefficientlyaswomencan.Thismakessurgeryriskierforme
Thestudentcannotregisterbecause______.
随机试题
下列选项中,国际运输保险的货运量最大的是()
多普勒频移与下面哪项无关
下列哪种诊断最准确为明确有无后纵韧带骨化,宜行哪项检查
十二指肠溃疡的直接X线征象是
房地产置业投资中,全部流动资金以货币资金形式被收回的时间在()。
实施素质教育是提高国民素质,培养跨世纪人才的战略举措,素质教育的特点是()。
在全县上下的共同努力下,某县户均税费负担逐年下降,2001年比2000年下降了3%,2002年比2001年下降了4%,2003年比2002年下降了5%,问2003年该县的户均税费负担比2000年下降了百分之几?()
下列句子中,加下划线的成语使用不恰当的一句是______。
根据蒙代尔一弗莱明模型简要分析开放经济条件下财政政策和货币政策的作用效果。
Healthyguiltisawarningsignalthateithersomethingdangerousisabouttohappenorsomethinghasalreadyhappenedthatneed
最新回复
(
0
)