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Lesson 43 Are there strangers in space? 宇宙中有外星人吗?

发布者: Q版辉仔 | 发布时间: 2006-11-24 19:46| 查看数: 10425| 评论数: 0|

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First listen and then answer the following question.

听录音,然后回答以下问题。

What does the ‘uniquely rational way’ for us to communicate with other intelligent beings in space depend on?

We must conclude from the work of those who have studied the origin of life, that given a planet only approximately like our own, life is almost certain to start. Of all the planets in our own solar system, we are now pretty certain the Earth is the only one on which life can survive. Mars is too dry and poor in oxygen, Venus far too hot, and so is Mercury, and the outer planets have temperatures near absolute zero and hydrogen-dominated atmospheres. But other suns, stars as the astronomers call them, are bound to have planets like our own, and as the number of stars in the universe is so vast, this possibility becomes virtual certainty. There are one hundred thousand million stars in our own Milky Way alone, and then there are three thousand million other Milky Ways, or galaxies, in the universe. So the number of stars that we know exist is now estimated at about 300 million million million.

Although perhaps only 1 per cent of the life that has started somewhere will develop into highly complex and intelligent patterns, so vast is the number of planets, that intelligent life is bound to be a natural part of the universe.

If then we are so certain that other intelligent life exists in the universe, why have we had no visitors from outer space yet? First of all, they may have come to this planet of ours thousands or millions of years ago, and found our then prevailing primitive state completely uninteresting to their own advanced knowledge. Professor Ronald Bracewell, a leading American radio astronomer, argued in Nature that such a superior civilization, on a visit to our own solar system, may have left an automatic messenger behind to await the possible awakening of an advanced civilization. Such a messenger, receiving our radio and television signals, might well re-transmit them back to its home-planet, although what impression any other civilization would thus get from us is best left unsaid.

But here we come up against the most difficult of all obstacles to contact with people on other planets ----the astronomical distances which separate us. As a reasonable guess, they might, on an average, be 100 light years away. (A light year is the distance which light travels at 186,000 miles per second in one year, namely 6 million million miles.) Radio waves also travel at the speed of light, and assuming such an automatic messenger picked up our first broadcasts of the 1920's, the message to its home planet is barely halfway there. Similarly, our own present primitive chemical rockets, though good enough to orbit men, have no chance of transporting us to the nearest other star, four light years away, let alone distances of tens or hundreds of light years.

Fortunately, there is a ‘uniquely rational way’ for us to communicate with other intelligent beings, as Walter Sullivan has put it in his excellent book, We Are not Alone. This depends on the precise radio frequency of the 21-cm wavelength, or 1420 megacycles per second. It is the natural frequency of emission of the hydrogen atoms in space and was discovered by us in 1951; it must be known to any kind of radio astronomer in the universe

Once the existence of this wave-length had been discovered, it was not long before its use as the uniquely recognizable broadcasting frequency for interstellar communication was suggested. Without something of this kind, searching for intelligences on other planets would be like trying to meet a friend in London without a pre-arranged rendezvous and absurdly wandering the streets in the hope of a chance encounter.

ANTHONY MICHAELIS Are There Strangers in Space? from The Weekend Telegraph

New words and expressions生词和短语

Mercury(1.4)/'m*:kjuri/n.水星

cm(1.31)(=centimetre/'senti?mi:t+/)n. 厘米

hydrogen(11.4-5)/'haidr+dN+n/n.氢气

megacycle(1.31)/'meg+?saik+l/n.兆周

prevailing(1.15)/pri'veiliR/adj.普遍的

emission(1.31)/I'miM+m/n.散发

radio astronomer(1.16)/'reidi+u+'str%n+m+/射电天文学家

intersteller(1.35)/?int+'stel+/adj. 星际的

rendezvous(1.37)/'r%ndivu:/n. 约会地点

uniquely (1.29)/ju:'ni:kli/adv.唯一地

encounter(1.37)/in'kaunt+/n.相遇

rational(1.29)/'r$M+n+l/adj.合理的

radio frequency(11.30-31)/'reidi+(>fri:kw+nsi/无线电频率

Notes on the text课文注释

1 that given a planet…certain to start, 这是一个宾语从句,作动词conclude的宾语,其中given a planet…our own,过去分词短语作条件状语,given与 if的意思相近,这个过去分词短语可译成“如果一个行星与我们所在的行星大致相同的话”。

2 is best left unsaid,最好不去说(它)。

3 come up against,遇到。

参考译文

根据研究生命起源的人们所作的工作,我们必然会得出这样的结论:如果设想有一颗行星和我们地球的情况基本相似,那几乎肯定会产生生命。我们目前可以肯定的是,在我们太阳系的所有行星中,地球是生命能存在的唯一行星。火星太干燥又缺氧,金星太热,水星也一样。除此以外,太阳系的其他行星的温度都接近绝对零度,并围绕着以氢气为主的大气层。但是,其他的太阳,即天文学家所说的恒星,肯定会有像我们地球一样的行星。因为宇宙中恒星的数目极其庞大,所以存在着产生生命星球的这种可能性是肯定无疑的。仅我们的银河系就有1000亿颗恒星,况且在宇宙中还有30亿个天河,即银河系。因此,我们所知道的现有恒星数目估计约有30亿×1000亿颗。

虽然在已经产生生命的某个地方,可能只有1%会发展成高度复杂有智力的生命形态,但是行星的数目是那么庞大,有智力的生命必然是宇宙的自然组成部分。

既然我们如此坚信宇宙中存在着其他有智力的生命,那么我们为什么还未见到外层空间来访的客人呢?首先,他们可能在几千年前或几百年万年前已来过我们地球,并且发现我们地球当时普遍存在着的原始状态同他们先进的知识相比是索然无味的。美国一位重要的射电天文学家罗纳德·布雷斯韦尔教授在《自然》杂志上提出了这样的观点:假如有如此高级文明生命访问了我们的太阳系,很可能会在离开太阳系时留下自动化信息装置,等待先进文明的觉醒。这种自动化信息装置,在接收到我们的无线电和电视信号后,完全有可能把这些信号发回到原来的行星。至于其他文明行星对我们地球会有什么印象,还是不说为好。

然而,在和外星人联系中我们遇到的最大困难是分隔我们的天文距离。据合理推算,外星人离我们平均距离也有100光年之远(1光年是光以每秒186,000英里的速度在一年内走的距离,即6万亿英里)。无线电波也是以光速传播的。假定外星人的这种自动化信息装置接收到了我们二十世纪二十年代的第一次广播信号,那么这个信号在发回到原来的行星途中刚刚走了一半路程。同样,我们目前使用的原始化学火箭,虽然可以把人送入轨道,但尚不可能把我们送到离我们最近、相距4光年的其他星球上去,更不用说几十光年或几百光年远的地方了。

幸运的是,有一种我们可以和其他智力生命通迅联系的“唯一合理的方法”,正如沃尔特·沙利文在其杰作《我们并不孤独》中阐述的。这种通讯联系要靠21厘米波段,即每秒1420兆周的精确无线电频率。这个频率是空间氢原子释放的自然频率,是在1951年被人类发现的。这个频率是宇宙中任何射电天文学家都应该熟悉的。

一旦这种波长的实际存在被发现,提出把它作为星际间唯一可辨认的广播频率就为期不远了。没有这种手段,要想寻觅其他星球上的智力生命,就如同去伦敦见一位朋友,事先未约定地点,而荒唐地在街上游逛,以期碰巧遇上一样。

Comprehension 理解

Answer these questions:

1 What do you understand by the word‘galaxy’?

2 Why, according to the author, is it highly probable that life exists in other parts of the universe?

3 Why would it be extremely difficult to visit another planet even if one were travelling at 186,000 miles per second?

4 How might it be possible to accomplish interstellar communication?

Vocabulary词汇

Refer to the text to see how the following words have been used, then write sentences of your own using these words: approximately (1.2);prevailing primitive state(1.15);automatic messenger(1.17);obstacles(1.21);orbit(1.26); interstellar(1.35); chance encounter(1.37).

Summary摘要

Drawing your information from lines 21-37 (‘But here ... chance encounter.’), write an account of the difficulties of interstellar communication. Do not write more than 100 words. Use your own words as far as possible. Your answer should be in one paragraph.

Composition作文

Write a composition of about 600 words on one of the following subjects:

1 The universe.

2 Flying saucers.

3 If an outside observer were given the opportunity to spend a year on earth, what impression might he get of its inhabitants?

Key structures 关键句型

A Note the form of the verb in italics:

But other suns are bound to have planets like our own. (11.5-6)

Write sentences using the following expressions:

sure to; about to; due to.

B Rewrite the sentences given below using the opening phrases provided. Do not refer to the passage until you have finished the exercise:

1 As the number of planets is so vast, intelligent life is bound to be a natural part of the universe.

So vast ______ (1.11)

2 First of all, it is possible that they came to this planet of ours thousands or millions of years ago.

First of all, they may _______(1.14)

3 It was argued in Nature by Professor Ronald Bracewell, a leading American radio astronomer, that such a superior civilization, on a visit to our own solar system, may have left an automatic messenger behind.

Professor Ronald Bracewell, _____ (11.16-17)

4 Even if our own present primitive chemical rockets are good enough to orbit men, they have no chance of transporting us to the nearest other star.

Our own present ... though ______ (11.26-27)

Special difficulties难点

A Study the following pairs of words and then write sentences of your own to bring out the difference.

1 planet (1.2) ---- star (1.6)

Live images of the robotic vehicle, Sojourner, have been relayed from the planet Mars to our T.V. screens in seconds.

There must be other stars, like our own sun, with orbiting planets similar to Earth.

2 estimated (1.9) ---- esteemed

The cost of repair has been estimated at $45.

German mechanical engineering is highly esteemed world-wide.

3 natural (1.11) ---- physical

It's quite natural for a boy's voice to break when he is about 14.

Boxers take a lot of physical punishment.

4 unsaid (1.20) ---- untold

Some things are better left unsaid.

The floods have caused untold misery to hundreds of thousands of farmers this year.

5 search for (1.36) ---- search

The whole village has been searching for the missing boy.

The security guards are searching each passenger.

B Note the use of let alone in this sentence:

Similarly, our own present primitive chemical rockets, though good enough to orbit men, have no chance of transporting us to the nearest other star, four light years away, let alone distances of tens or hundreds of light years. (11.26-28)

Complete the following sentences:

1 He's incapable of adding up a simple list of figures, let alone ______

2 He doesn't earn enough to support himself, let alone_____

Multiple choice questions 多项选择题

Choose the correct answers to the following questions.

Comprehension 理解

1 The possibility that life exists on other planets is almost certain because ______ .

a.there are plenty of planets like our own

b.the other planets in our solar system are unlikely to support life

c.our own galaxy is so large

d.of the sheer number of planets in the universe

2 According to the writer, ____.

a.there is a possibility that we constantly have visitors from outer space

b.our planet may have been visited at some time during the distant past

c.an automatic messenger was left on our planet at some time in the past

d.our civilization is just awakening and is of interest to other beings

3 Travel in the universe is difficult because ____.

a.even at the speed of light, distances are immense

b.light travels at 186,000 miles per hour

c.planets are 100 light years away

d.there are no rockets in the universe powerful enough

4 The discovery of the natural frequency of emission of hydrogen atoms in space is important because ________.

a.it's a precise radio frequency of 1420 megacycles per second

b.it would be universally recognized by intelligent life anywhere in the universe

c.it makes the discovery of intelligent life elsewhere virtually certain

d.hydrogen is abundant exclusively in our own solar system

Structure 句型

5 Life ______ present on a planet approximately like our own. (11.1-2)

a.was

b.might be

c.must be

d.is

6 Why have we had no visitors from outer space_____ ? (11.13-14)

a.before

b.in the past

c.so far

d.till then

7 They were not ______our primitive state. (1.15)

a.interesting to (6) interesting in

c.interested to

d.interested in

8 We have no chance ______by our own primitive chemical rockets. (11.26-27)

a.to be transporting

b.to transport

c.of transporting

d.of being transported

Vocabulary词汇

9 They are_____ to have planets like our own.(11.5-6)

a.almost certain

b.obliged

c.required

d.due

10 What impression they would get of us is best left _____.(11.19-20)

a.unspoken

b.untold

c.unmentioned

d.unrecounted

11 We come up against the most difficult of all obstacles to ____people.(1.21)

a.speaking to

b.being in touch with

c.touching

d.reaching out to

12 This depends on the _____radio frequency of the 21cm wavelength. (11.30-31)

a.measurable

b.exact

c.established

d.known


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