新概念第四冊課文精講 Lesson43:宇宙中有外星人嗎？
課文43 宇宙中有外星人嗎?
832. We must conclude from the work of those who have studied the origin of life,
根據(jù)研究生命起源的人們所作的工作，我們必然會得出這樣的結(jié)論：
833. that given a planet only approximately like our own, life is almost certain to start.
如果設(shè)想有一顆行星和我們地球的情況基本相似，那幾乎肯定會產(chǎn)生生命。
834. Of all the planets in our solar system, we ware now pretty certain the Earth is the only one on which life can survive.
我們目前可以肯定的是，在我們太陽系的所有行星中，地球是生命能存在的唯一行星。
835. Mars is too dry and poor in oxygen,
火星太干燥又缺氧，
836. Venus far too hot, and so is Mercury,
金星太熱，水星也一樣。
837. and the outer planets have temperatures near absolute zero and hydrogen-dominated atmospheres.
除此之外，太陽系的其他行星的溫度都接近絕對零度，并圍繞著以氫氣為主的大氣層。
838. But other suns, start as the astronomers call them, are bound to have planets like our own, and as is the number of stars in the universe is so vast, this possibility becomes virtual certainty.
但是，其他的太陽，既天文學(xué)家所說的恒星，肯定會有像我們地球一樣的行星。因為宇宙中恒星的數(shù)目極其龐大，所以存在著產(chǎn)生生命星球的這種可能性是肯定無疑的。
839. There are one hundred thousand million starts in our own Milky Way alone, and then there are exist is now estimated at about 300 million million.
僅我們的銀河系就有1000億顆星，況且在宇宙中還有30億個天河，即銀河系。因此，我們所知道的現(xiàn)有恒星數(shù)目估計約有30億X1000億顆。
840. Although perhaps only 1 per cent of the life that has started somewhere will develop into highly complex and intelligent patterns,
雖然在已經(jīng)產(chǎn)生生命的某個地方，可能只有1%會發(fā)展成高度復(fù)雜有智力的生命形態(tài)，
841. so vast is the number of planets, that intelligent life is bound to be a natural part of the universe.
但是行星的數(shù)目是那么龐大，有智力的生命必然是宇宙的自然組成道聽部分。
842. If then we are so certain that other intelligent life exists in the universe,
既然我們?nèi)绱藞孕庞钪嬷写嬖谥渌兄橇Φ纳?/p>
843. why have we had no visitors from outer space yet?
那么我們?yōu)槭裁催€未見到外層空間來訪的客人呢?
844. First of all, they may have come to this planet of ours thousands or millions of years ago,
首先，他們可能在幾千年前或幾百年前已來過我們地球，
845. and found our then prevailing primitive state completely uninteresting to their own advanced knowledge.
并且發(fā)現(xiàn)我們地球漢時普遍存在著的原始狀態(tài)同他們的先進的知識相比是索然無味的。
846. Professor Ronald Bracewell, a leading American radio astronomer, argued in Nature that such a superior civilization,
美國一位重要的射電天文學(xué)家羅納德.布雷斯韋爾教授在《自然》雜志上提出了這樣的觀點：
847. on a visit to our own solar system, may have left an automatic messenger behind to await the possible awakening of an advanced civilization.
假如有如此高級文明生命訪問了我們的太陽系，很可能會在離開太陽系時留下自動化信號裝置，等待先進文明的覺醒。
848. Such a messenger, receiving our radio and television signals, might well re-transmit them back to its home-planet,
這種自動化信息裝置，在接收到我們的無線電和電視信號后，完全有可能把這些信號發(fā)回到原來的行星。
849. although what impression any other civilization would thus get from us is best left unsaid.
至于其他文明行星對我們地球會有什么印象，還是不說為好。
850. 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.
然而，在和外星人聯(lián)系中我們遇到的最大困難是分隔我們的天文距離。
851. As a reasonable guess, they might, on an average, be 100 light years away.
據(jù)合理推算，外星人離我們平均距離也有100光年之遠(yuǎn)
852. Radio waves also travel at the speed of light,
無線電波也是以光速傳播的。
853. and assuming such an automatic messenger picked up our first broadcasts of the 1920's,
假定外星人的這種自動化信息裝置接收了我們二十世紀(jì)二十年代的第一次廣播信號，
854. the message to its home planet is barely halfway there.
那么這個信號在發(fā)回到原來的行星途中剛剛走了一半路程。
855. Similarly, our own present primitive chemical rockets, though good enough to orbit men,
同樣，我們目前使用的原始化學(xué)火箭，雖然把人送入軌道，
856. 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.
但尚不能把我們送到離我們最近、相距4光年的其他星球上去，更不用說幾十光年或幾百光年遠(yuǎn)的地方了。
857. Fortunately, there is a 'uniquely rational way' for us to communicate with other intelligent beings,
幸運的是，有一種我們可以和其他智力生命通迅聯(lián)系的“唯一合理的方法”，
858. as Walter Sullivan has put it in his excellent book, We Are not Alone.
正如活爾特.沙利方在其杰作《我們并不孤獨》中闡述的。
859. This depends on the precise radio frequency of the 21-cm wavelength, or 1420 megacycles per second.
這種通迅聯(lián)系要靠21厘料波段，即每秒1420兆周的精確無線電頻率。
860. It is the natural frequency of emission of the hydrogen atoms in space and was discovered by us in 1951;
這個頻率是空間氫原子釋放的自然頻率，是在1951年被人類發(fā)現(xiàn)的。
861. it must be known to any kind of radio astronomer in the universe.
這個頻率是宇宙中任何射電天文學(xué)家都應(yīng)該熟悉的。
862. 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.
一旦這種波長的實際存在被發(fā)現(xiàn)，提出把它作為星際間唯一可辨認(rèn)的廣播頻率就為期不遠(yuǎn)了。
863. 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.
沒有這手段，要想尋覓其他星球上的智力生命，就如同去倫敦見一位朋友，事先未約定地點，而荒唐地在街上游逛，以期待碰巧遇上一樣。
