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 What is a black hole? Well, it’s difficult to answer this question, since the terms we normally use to describe a sc
Black Holes What is a black hole? Well, it’s difficult to answer this question, since the terms we normally use to describe a sc
admin
2009-06-15
56
问题
Black Holes
What is a black hole? Well, it’s difficult to answer this question, since the terms we normally use to describe a scientific phenomenon are inadequate here, 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 (施加) a strong gravitational (重力的) 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 (超新星) occurs. The collapse of a star may produce a "White Dwarf (白矮星) "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 this process of shrinking may be so intense that a black hole results. 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. Einstein’s theory provided a basis for the idea of black holes before astronomers started to find some evidence 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 (由两部分组成的) star systems. In some binary star 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.
选项
A、The black hole is a region of space.
B、The black hole sucks in any object that passes by it.
C、The black hole is visible through an infrared telescope.
D、The black hole has no matter.
答案
C
解析
转载请注明原文地址:https://kaotiyun.com/show/QrQd777K
本试题收录于:
职称英语理工类B级题库职称英语分类
0
职称英语理工类B级
职称英语
相关试题推荐
TheUSfacessevereeconomicproblems.
MigrantWorkersInthepasttwentyyears,therehasbeenanincreasingtendencyforworkerstomovefromonecountrytoanot
PublicRelationsPublicrelationsisabroadsetofplannedcommunicationsaboutthecompany,includingpublicityreleases,
SleeplessnessInsomniaorsleeplessnessisacommoncomplaintofwomenastheyenterintomenopause.Insomniameanshavingt
WhatisSunsetSongmainlyabout?Theword"Sunset"inthetitleofthisnovelmostprobablymeans
Hewastemptedbythehighsalaryofferedbythecompany.
A.havehealingeffectsB.beusedexternallyC.bepromotedD.helpthedisabledE.befurtherexploredF.suitdifferentpeopl
AinyourbodyBwithoutwaterCbeforelongDforachangeEonabusydayFtoyourweightDon’tforgettodrinkenoughwater
Martindecidedthathehadnoadequateproof.
Thecuriouslooksfromthestrangersaroundhermadeherfeeluneasy.
随机试题
高血压性脑出血手术治疗的指征?其目的?
鉴别尿路感染与尿道综合征的最根本点是
舌下腺囊肿的根治方法是完整切除囊肿。()
关于企业集团叙述不正确的是:()。
关于保险合同,下列叙述不正确的是()。
关于乳母营养需要,说法正确的有()。
AlfredNobelbecameamillionaireandchangedthewaysofmining,construction,andwarfareastheinventorofdynamite(炸药).On
四十三年,望中犹记,_________。(辛弃疾《永遇乐.京口北固亭怀古》)
社会主义核心价值体系和社会主义核心价值观,是决定文化性质和方向的最深层次要素,是一个国家的重要稳定器。以下关于社会主义核心价值体系和社会主义核心价值观相互关系的论述中,正确的是
某投资者上一交易日结算准备金余额为157475元,上一交易日交易保证金为11605元,当日交易保证金为18390元,当日平仓盈亏为8500元,当日持仓盈亏为7500元,手续费等其他费用为600元,当日该投资者又在其保证金账户中存入资金50000
最新回复
(
0
)