Before 1970, my research on general relativity hadconcentrated mainly on the question of whether or not therehad been a big bang singularity. However, one evening inNovember that year, shortly after the birth of my daughter,Lucy, I started to think about black holes as I was getting intobed. My disability makes this rather a slow process, so I hadplenty of time. At that date there was no precise definition ofwhich points in space-time lay inside a black hole and whichlay outside. I had already discussed with Roger Penrose theidea of defining a black hole as the set of events from which itwas not possible to escape to a large distance, which is nowthe generally accepted definition. It means that the boundary ofthe black hole, the event horizon, is formed by the light raysthat just fail to escape from the black hole, hovering¹ foreverjust on the edge (Fig². 7.1). It is a bit like running away fromthe police and just managing to keep one step ahead but notbeing able to get clear away!
Suddenly I realized that the paths of these light rays couldnever approach one another. If they did they must eventuallyrun into one another. It would be like meeting someone elserunning away from the police in the opposite direction - youwould both be caught! (Or, in this case, fall into a black hole.)But if these light rays were swallowed up by the black hole,then they could not have been on the boundary of the blackhole. So the paths of light rays in the event horizon hadalways to be moving parallel to, or away from, each other.
Another way of seeing this is that the event horizon, theboundary of the black hole, is like the edge of a shadow - theshadow of impending³ doom⁴. If you look at the shadow cast bya source at a great distance, such as the sun, you will see thatthe rays of light in the edge are not approaching each other.
If the rays of light that form the event horizon, theboundary of the black hole, can never approach each other,the area of the event horizon might stay the same or increasewith time, but it could never decrease because that would meanthat at least some of the rays of light in the boundary wouldhave to be approaching each other. In fact, the area wouldincrease whenever matter or radiation fell into the black hole(Fig. 7.2). Or if two black holes collided and merged

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1 hovering
鸟( hover的现在分词 )； 靠近（某事物）； （人）徘徊； 犹豫
参考例句：
The helicopter was hovering about 100 metres above the pad. 直升机在离发射台一百米的上空盘旋。 I'm hovering between the concert and the play tonight. 我犹豫不决今晚是听音乐会还是看戏。

2 fig
n.无花果(树)
参考例句：
The doctor finished the fig he had been eating and selected another.这位医生吃完了嘴里的无花果，又挑了一个。 You can't find a person who doesn't know fig in the United States.你找不到任何一个在美国的人不知道无花果的。

3 impending
a.imminent, about to come or happen
参考例句：
Against a background of impending famine, heavy fighting took place. 即将发生饥荒之时，严重的战乱爆发了。 The king convoke parliament to cope with the impending danger. 国王召开国会以应付迫近眉睫的危险。

4 doom
n.厄运，劫数；v.注定，命定
参考例句：
The report on our economic situation is full of doom and gloom.这份关于我们经济状况的报告充满了令人绝望和沮丧的调子。 The dictator met his doom after ten years of rule.独裁者统治了十年终于完蛋了。

5 merged
（使）混合( merge的过去式和过去分词 )； 相融； 融入； 渐渐消失在某物中
参考例句：
Turf wars are inevitable when two departments are merged. 两个部门合并时总免不了争争权限。 The small shops were merged into a large market. 那些小商店合并成为一个大商场。

6 restriction
n.限制，约束
参考例句：
The park is open to the public without restriction.这个公园对公众开放，没有任何限制。 The 30 mph speed restriction applies in all built-up areas.每小时限速30英里适用于所有建筑物聚集区。

7 disorder
n.紊乱，混乱；骚动，骚乱；疾病，失调
参考例句：
When returning back,he discovered the room to be in disorder.回家后，他发现屋子里乱七八糟。 It contained a vast number of letters in great disorder.里面七零八落地装着许多信件。

8 expenditure
n.(时间、劳力、金钱等)支出；使用，消耗
参考例句：
The entry of all expenditure is necessary.有必要把一切开支入账。 The monthly expenditure of our family is four hundred dollars altogether.我们一家的开销每月共计四百元。

9 molecules
分子( molecule的名词复数 )
参考例句：
The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。 Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

10 initially
adv.最初，开始
参考例句：
The ban was initially opposed by the US.这一禁令首先遭到美国的反对。 Feathers initially developed from insect scales.羽毛最初由昆虫的翅瓣演化而来。

11 violation
n.违反(行为)，违背(行为)，侵犯
参考例句：
He roared that was a violation of the rules.他大声说，那是违反规则的。 He was fined 200 dollars for violation of traffic regulation.他因违反交通规则被罚款200美元。

12 pointed
adj.尖的，直截了当的
参考例句：
He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。 She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。

13 apparently
adv.显然地；表面上，似乎
参考例句：
An apparently blind alley leads suddenly into an open space.山穷水尽，豁然开朗。 He was apparently much surprised at the news.他对那个消息显然感到十分惊异。

14 irritation
n.激怒，恼怒，生气
参考例句：
He could not hide his irritation that he had not been invited.他无法掩饰因未被邀请而生的气恼。 Barbicane said nothing,but his silence covered serious irritation.巴比康什么也不说，但是他的沉默里潜伏着阴郁的怒火。

15 Soviet
adj.苏联的，苏维埃的；n.苏维埃
参考例句：
Zhukov was a marshal of the former Soviet Union.朱可夫是前苏联的一位元帅。 Germany began to attack the Soviet Union in 1941.德国在1941年开始进攻苏联。

16 uncertainty
n.易变，靠不住，不确知，不确定的事物
参考例句：
Her comments will add to the uncertainty of the situation.她的批评将会使局势更加不稳定。 After six weeks of uncertainty,the strain was beginning to take its toll.6个星期的忐忑不安后，压力开始产生影响了。

17 emission
n.发出物，散发物；发出，散发
参考例句：
Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施，降低污染物排放总量。 Finally,the way to effectively control particulate emission is pointed out.最后，指出有效降低颗粒排放的方向。

18 Oxford
n.牛津（英国城市）
参考例句：
At present he has become a Professor of Chemistry at Oxford.他现在已是牛津大学的化学教授了。 This is where the road to Oxford joins the road to London.这是去牛津的路与去伦敦的路的汇合处。

19 valid
adj.有确实根据的；有效的；正当的，合法的
参考例句：
His claim to own the house is valid.他主张对此屋的所有权有效。 Do you have valid reasons for your absence?你的缺席有正当理由吗？

20 violations
违反( violation的名词复数 )； 冒犯； 违反（行为、事例）； 强奸
参考例句：
This is one of the commonest traffic violations. 这是常见的违反交通规则之例。 These violations of the code must cease forthwith. 这些违犯法规的行为必须立即停止。

21 velocity
n.速度，速率
参考例句：
Einstein's theory links energy with mass and velocity of light.爱因斯坦的理论把能量同质量和光速联系起来。 The velocity of light is about 300000 kilometres per second.光速约为每秒300000公里。

22 accurately
adv.准确地，精确地
参考例句：
It is hard to hit the ball accurately.准确地击中球很难。 Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。

23 fixed
adj.固定的，不变的，准备好的；(计算机)固定的
参考例句：
Have you two fixed on a date for the wedding yet?你们俩选定婚期了吗？ Once the aim is fixed,we should not change it arbitrarily.目标一旦确定，我们就不应该随意改变。

24 fluctuations
波动，涨落，起伏( fluctuation的名词复数 )
参考例句：
He showed the price fluctuations in a statistical table. 他用统计表显示价格的波动。 There were so many unpredictable fluctuations on the Stock Exchange. 股票市场瞬息万变。

25 annihilate
v.使无效；毁灭；取消
参考例句：
Archer crumpled up the yellow sheet as if the gesture could annihilate the news it contained.阿切尔把这张黄纸揉皱，好象用这个动作就会抹掉里面的消息似的。 We should bear in mind that we have to annihilate the enemy.我们要把歼敌的重任时刻记在心上。

26 detector
n.发觉者，探测器
参考例句：
The detector is housed in a streamlined cylindrical container.探测器安装在流线型圆柱形容器内。 Please walk through the metal detector.请走过金属检测器。

27 remarkable
adj.显著的，异常的，非凡的，值得注意的
参考例句：
She has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。 These cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。

28 condemned
adj. 被责难的, 被宣告有罪的 动词condemn的过去式和过去分词
参考例句：
He condemned the hypocrisy of those politicians who do one thing and say another. 他谴责了那些说一套做一套的政客的虚伪。 The policy has been condemned as a regressive step. 这项政策被认为是一种倒退而受到谴责。

29 Forsaken
adj. 被遗忘的, 被抛弃的 动词forsake的过去分词
参考例句：
He was forsaken by his friends. 他被朋友们背弃了。 He has forsaken his wife and children. 他遗弃了他的妻子和孩子。

30 compensated
补偿，报酬( compensate的过去式和过去分词 )； 给（某人）赔偿（或赔款）
参考例句：
The marvelous acting compensated for the play's weak script. 本剧的精彩表演弥补了剧本的不足。 I compensated his loss with money. 我赔偿他经济损失。

31 destined
adj.命中注定的；(for)以…为目的地的
参考例句：
It was destined that they would marry.他们结婚是缘分。 The shipment is destined for America.这批货物将运往美国。

32 primordial
adj.原始的；最初的
参考例句：
It is the primordial force that propels us forward.它是推动我们前进的原始动力。 The Neanderthal Man is one of our primordial ancestors.的尼安德特人是我们的原始祖先之一.

33 collapse
vi.累倒；昏倒；倒塌；塌陷
参考例句：
The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。 The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做了一次彻底的调查分析。

34 wavelength
n.波长
参考例句：
The authorities were unable to jam this wavelength.当局无法干扰这一波长。 Radio One has broadcast on this wavelength for years.广播1台已经用这个波长广播多年了。

35 epithet
n.（用于褒贬人物等的）表述形容词，修饰语
参考例句：
In "Alfred the Great","the Great"is an epithet.“阿尔弗雷德大帝”中的“大帝”是个称号。 It is an epithet that sums up my feelings.这是一个简洁地表达了我思想感情的形容词。

36 nucleus
n.核，核心，原子核
参考例句：
These young people formed the nucleus of the club.这些年轻人成了俱乐部的核心。 These councils would form the nucleus of a future regime.这些委员会将成为一个未来政权的核心。

37 thereby
adv.因此，从而
参考例句：
I have never been to that city,,ereby I don't know much about it.我从未去过那座城市，因此对它不怎么熟悉。 He became a British citizen,thereby gaining the right to vote.他成了英国公民，因而得到了投票权。

38 immediate
adj.立即的；直接的，最接近的；紧靠的
参考例句：
His immediate neighbours felt it their duty to call.他的近邻认为他们有责任去拜访。 We declared ourselves for the immediate convocation of the meeting.我们主张立即召开这个会议。

39 detectable
adj.可发觉的；可查明的
参考例句：
The noise is barely detectable by the human ear.人的耳朵几乎是察觉不到这种噪音的。 The inflection point at this PH is barely detectable.在此PH值下，拐点不易发现。

40 intensity
n.强烈，剧烈；强度；烈度
参考例句：
I didn't realize the intensity of people's feelings on this issue.我没有意识到这一问题能引起群情激奋。 The strike is growing in intensity.罢工日益加剧。

41 galaxies
星系( galaxy的名词复数 )； 银河系； 一群（杰出或著名的人物）
参考例句：
Quasars are the highly energetic cores of distant galaxies. 类星体是遥远星系的极为活跃的核心体。 We still don't know how many galaxies there are in the universe. 我们还不知道宇宙中有多少个星系。

42 galaxy
n.星系；银河系；一群(杰出或著名的人物)
参考例句：
The earth is one of the planets in the Galaxy.地球是银河系中的星球之一。 The company has a galaxy of talent.该公司拥有一批优秀的人才。

43 Pluto
n.冥王星
参考例句：
Pluto is the furthest planet from the sun.冥王星是离太阳最远的行星。 Pluto has an elliptic orbit.冥王星的轨道是椭圆形的。

44 penetrate
v.透(渗)入；刺入，刺穿；洞察，了解
参考例句：
Western ideas penetrate slowly through the East.西方观念逐渐传入东方。 The sunshine could not penetrate where the trees were thickest.阳光不能透入树木最浓密的地方。

45 neutron
n.中子
参考例句：
Neutron is neutral and slightly heavier than the proton.中子是中性的，比质子略重。 Based on the neutron energy,the value of weighting factor was given.根据中子能量给出了相应的辐射权重因子的数值。

46 detectors
探测器( detector的名词复数 )
参考例句：
The report advocated that all buildings be fitted with smoke detectors. 报告主张所有的建筑物都应安装烟火探测器。 This is heady wine for experimenters using these neutrino detectors. 对于使用中微子探测器的实验工作者，这是令人兴奋的美酒。 来自英汉非文学 - 科技

47 chaotic
adj.混沌的，一片混乱的，一团糟的
参考例句：
Things have been getting chaotic in the office recently.最近办公室的情况越来越乱了。 The traffic in the city was chaotic.这城市的交通糟透了。

48 opposition
n.反对，敌对
参考例句：
The party leader is facing opposition in his own backyard.该党领袖在自己的党內遇到了反对。 The police tried to break down the prisoner's opposition.警察设法制住了那个囚犯的反抗。

49 immortality
n.不死，不朽
参考例句：
belief in the immortality of the soul 灵魂不灭的信念 It was like having immortality while you were still alive. 仿佛是当你仍然活着的时候就得到了永生。

50 derive
v.取得；导出；引申；来自；源自；出自
参考例句：
We derive our sustenance from the land.我们从土地获取食物。 We shall derive much benefit from reading good novels.我们将从优秀小说中获得很大好处。

51 onward
adj.向前的，前进的；adv.向前，前进，在先
参考例句：
The Yellow River surges onward like ten thousand horses galloping.黄河以万马奔腾之势滚滚向前。 He followed in the steps of forerunners and marched onward.他跟随着先辈的足迹前进。

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