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
2010-01-07
60
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.
【B1】
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. 【B2】
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. 【B3】
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. 【B4】
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. 【B5】
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.
选项
答案
试想,如果地球体积缩小到如同一块大理石,而其质量不变并且具有更强的吸引力,那么你就会对黑洞的力量有一点认识了。
解析
转载请注明原文地址:https://kaotiyun.com/show/65Pd777K
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
Beforeabigexam,asoundnight’ssleepwilldoyoubetterthanporingovertextbooks.That,atleast,isthefolkwisdom.And
RecentsurveysshowthatJapaneseyouthhavebecomea"MeGeneration"thatrejectstraditionalvalues."Around1980manyJa
RecentsurveysshowthatJapaneseyouthhavebecomea"MeGeneration"thatrejectstraditionalvalues."Around1980manyJa
Accordingtothespeaker,whatareconveniencegoods?
OverbreakfastFlorianIoanWells,a33-year-oldaerospaceengineer,andCraigParsley,a25-year-oldenvironmentaltechnician,
Allthatfault-findingaboutloweringcholesterolandeatinglessfatmustfinallybepayingoff.Accordingtoastudypublished
ProfessorWangwentonalecturetourtoEdinburgh.
"Internet"hascreatedanewvocabularythathascometorepresentahistoricaleraofchange.AskJohnMorse,publisherofMerr
In1959theaverageAmericanfamilypaid$989forayear’ssupplyoffood.In1972thefamilypaid$1,311.Thatwasaprice
Walking—likeswimming,Bicyclingandrunning—isanaerobicexercise,【C1】______buildsthecapacityforenergyoutputandphysica
随机试题
青春期
男,45岁,以突起头痛、头晕、呕吐半小时急诊入院。查体:浅昏迷,呼吸无大蒜味,皮肤湿冷,双瞳孔缩小,双肺可闻及散在湿啰音,有肌颤。抢救该患者时应禁用下列哪种治疗方法
对于评价范围内的在建和未建项目的大气污染源调查,可用()确定。
安全系数的提高应通过()来达到。
用现金直接办理经济业务的货币收支行为,称为( )。
某企业2016年年初与年末所有者权益分别为400万元和500万元,则该企业2016年的所有者权益增长率为()。
一般资料:夫妻共同来咨询,两人是大学同学,均30岁,本科学历,企业员工。案例介绍:婚后妻子不想马上要孩子,对性生活多有拒绝,决定要孩子后情况好了些,后妻子怀孕、生子,性生活明显减少。现在孩子2岁多,妻子主动时丈夫不为所动,妻子认可丈夫所说性生活的
请阅读下列材料:《导航与超链接》是某版初中信息技术教材八年级下学期第一单元第四课的教学内容,网页中的超链接功能可以使浏览者便捷地访问各个网页,快速地定位浏览的内容。超链接是指从一个网页指向另一个目标的链接关系,这个目标可以是另一个网页,也可以是另一个图片
劳动教养是只对有违法行为且屡教不改者所采取的强制性教育改造的行政强制措施。()
“李老师”中“李”实际读音的调值是________。(广西民族大学2017)
最新回复
(
0
)