【導(dǎo)讀】的確，一個(gè)人如果沒有從事研究工作的基本。么他就會(huì)在學(xué)習(xí)和工作中碰到許多障礙。教育（學(xué)）、廣告與市場(chǎng)營(yíng)銷、經(jīng)濟(jì)學(xué)與會(huì)計(jì)學(xué)，者，都有四個(gè)主要部分。是報(bào)告的核心通常由這四大部分組成的。研究報(bào)告的首要部分就是陳述研究項(xiàng)。目所涉及的問題。這一部分要求準(zhǔn)確闡述研究者。要問答的根本問題。在這同一個(gè)部分里應(yīng)該從社

　　

【正文】 out which we know very little indeed. When we do the arithmetic, the sorts of numbers we e up with are, characteristically, around a million technical civilizations. A million civilizations is a breathtakingly large number, and it is exhilarating to imagine the diversity, lifestyles and merce of those million worlds. But the Milky Way Galaxy contains some 250 billion stars, and even with a million civilizations, less than one star in 200,000 would have a pla inhabited by an advanced civilization. Since we have little idea which stars are likely candidates, we will have to examine a very large number of them. Such considerations suggest that the quest for extraterrestrial intelligence may require a significant effort. Despite claims about ancient astronauts and unidentified flying objects, there is no firm evidence for past visitation of the Earth by other civilizations. We are restricted to remote signaling and, of the longdistance techniques available to our technology, radio is by far the best. Radio telescopes are relatively inexpensive。 radio signals travel at the speed of light, faster than which nothing can go。 and the use of radio for munication is not a shortsighted or anthropocentric activity. Radio represents a large part of the electromagic spectrum and any technical civilization anywhere in the Galaxy will have discovered radio early just as in the last few centuries we have explored the entire electromagic spectrum from short gamma rays to very long radio waves. Advanced civilizations might very well use some other means of munication with their peers. But if they wish to municate with backward or emerging civilizations, there are only a few obvious methods, the chief of which is radio. The first serious attempt to listen for possible radio signals from other civilizations was carried out at the National Radio Astronomy Observatory in Greenbank, West 一些研究外星人問題的科學(xué)家，包括我自己，都已努力設(shè)法對(duì)銀河系的先進(jìn)技 術(shù)文明社會(huì)的數(shù)目進(jìn)行了估計(jì) ——先進(jìn)技術(shù)文明社會(huì)定義為具有射民天文學(xué)能力的社會(huì)。這樣的估計(jì)比猜想強(qiáng)不了多少。 它們要求將這些情況數(shù)字化，諸如星球的數(shù)量和年齡，有多少個(gè)行星系、生命起源的可能性有多大，這些我們較少知道：還有智慧生物進(jìn)化的可能性和技術(shù)文明世界的壽命，這些我們近乎一無(wú)所知。 當(dāng)我們進(jìn)行計(jì)算時(shí)我們得出的這類數(shù)字是很有特點(diǎn)的大約有一百萬(wàn)個(gè)文明世界。想象一下這百萬(wàn)個(gè)文明世界的五花八門、這真令人興奮，各種生活方式以及商業(yè)，可是銀河系有大約二千五百億個(gè)恒星，即使有一百萬(wàn)個(gè)文明世界，可每二十萬(wàn)個(gè)恒星中不到一個(gè)有 文明世界的人居住的行星。既然我們幾乎不知道哪些恒星可能存在文明世界，我們將不得不搜尋大量的恒星。這樣就意味著探尋外星人可能需要作出極大的努力。 盡管有人聲稱古代在太空人，見過不明飛行物，然而卻缺乏確鑿的證據(jù)證明過去有其他文明世界的人來過地球。我們只限于運(yùn)用遠(yuǎn)距離的通信，在目前我們的技術(shù)所能運(yùn)用的長(zhǎng)距離的技術(shù)手段中，無(wú)線電肯定是最好的。無(wú)線電望遠(yuǎn)鏡相對(duì)來說價(jià)格便宜；無(wú)線電象光速那樣快速發(fā)送信號(hào)，而且前沒有任何東西快過光速；把無(wú)線電用于通訊不是一種短視的或以人類為宇宙中心的行為。無(wú)線電具有大部分的電磁波譜，銀河 系中的任何地方的任何技術(shù)文明世界該早就發(fā)現(xiàn)無(wú)線電，無(wú)線電具有大部分的電磁波譜，銀河系中的任何地方的任何技術(shù)文明世界該早就發(fā)現(xiàn)無(wú)線電了 ——正像在過去的幾個(gè)世紀(jì)中我們對(duì)從短伽馬射線到長(zhǎng)線電波的整個(gè)電磁波譜已經(jīng)探索過了一樣。先進(jìn)的文明社會(huì)要能使用其它的通訊方式同他們的同輩進(jìn)行聯(lián)系。但是，假如他們想和落后的或新興的文明社會(huì)聯(lián)系，很顯然只有幾種方法，其中主要的方法就是無(wú)線電。 在西旨吉尼亞州格林班克國(guó)家無(wú)線電天文臺(tái)第一次認(rèn)真的嘗試收聽了來自其他文明的信號(hào)。在１９５９年和１９６０年。此項(xiàng)工作是由弗蘭克 德雷克主持的，他 現(xiàn)在在康乃爾大學(xué)。這是以?shī)W茲 Virginia, in 1959 and 1960. It was anized by Frank Drake, now at Cornel University, and was called Project Ozma, after the princess of the Land of Oz, a place very exotic, very distant and very difficult to reach. Drake examined two nearby stars for a few weeks with negative results. Positive results would have been astonishing because as we have seen, even rather optimistic estimates of the number of technical civilizations in the Galaxy imply that several hundred thousand stars must be examined in order to achieve success by random stellar selection. Since Project Ozma, there have been six or eight other such programs, all at a rather modest level, in the United States, Canada and the Soviet Union. All results have been negative. The total number of individual stars examined to date in this way is less than a thousand. We have performed something like one tenth of one percent of the required effort. However, there are signs that much more serious efforts may be mustered in the reasonably near future. Besides, hand in hand with the recent spectacular advances in radio technology, there has been a dramatic increase in the scientific and public respectability of the entire subject of extraterrestrial life. A clear sign of the new attitude is the Viking missions to Mars, which are to a significant extent dedicated to the search for life on another pla. But along with the burgeoning dedication to a serious search, a slightly negative note has emerged which is nevertheless very interesting. A few scientists have lately asked a curious question: If extraterrestrial intelligence is abundant, why have we not already seen its manifestations? Skeptics also ask why there is no clear evidence of extraterrestrial visits to Earth. We have already launched slow and modest interstellar spacecraft. A society more advance than ours should be able to ply the spaces between the stars conveniently if not effortlessly. Over millions of years such societies should have established colonies, which might themselves launch interstellar expeditions. Why are they not here? The temptation is to deduce that there are at most a few advanced extraterrestrial civilizations either because statistically we are one of the first technical civilizations to have emerged or because it is the fate of all such civilizations to destroy themselves before they are much further along than we. It seems to me that such despair is quite premature. All such arguments depend on our correctly surmising the intentions of beings far more advanced than ourselves, and when examined more closely I think these arguments 國(guó)公主的名字命名的，叫作奧茲瑪項(xiàng)目。奧茲國(guó)是個(gè)十分奇異、非常遙遠(yuǎn)，難以到達(dá)的地方。德雷克在幾個(gè)星期里對(duì)兩個(gè)附近的恒星進(jìn)行了探測(cè)，沒有取得積極的結(jié)果。假如取得了積極的結(jié)果，那會(huì)令人吃驚的，因?yàn)?，正象我們已?jīng)看到的一樣，即使非常樂觀地估算一下銀河系中的技術(shù)文明社會(huì)的數(shù)目 ,要想不加選擇地探測(cè)就取得成功的話，必須探測(cè)幾十萬(wàn)個(gè)恒星。 自從奧茲瑪項(xiàng)目以來，又有６到８?jìng)€(gè)這樣規(guī)模的項(xiàng)目。都是這樣的規(guī)模，無(wú)論是在美國(guó)，加拿大和蘇聯(lián)。所有都未取得結(jié)果到目前為止用這種方法探測(cè)過的恒星總數(shù)還不到一千個(gè)， 也就是我們大約只探測(cè)了需要探測(cè)的百分之一中的十分之一?？墒?，種種跡象表明，人們可