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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 entiresubject 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 planet.
然而，有跡象表明，在不遠的將來，人們會作出更大的努力。此外，與無線電技術獲得十分可觀的進展相一致的是，無論是在科學界還是在社會上，人們對地球外天體中的生命這一整個課題的重要性的認識，有了極大的提高。這種新的態度的明顯標志，是"海盜"號火星探測器的發射。這些發射很大程度上是用來搜尋另一顆行星上的生命的。
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.
不過，隨著人們傾注越來越多的精力認真進行探索的時候，出現了一種稍帶否定意味卻又是很有趣的調子。幾位科學家近來問了一個奇怪的問題：如果地球外的天體中存在著許多具有高度智慧的生物，那么為何我們迄今尚未能見到足以表明他們存在的證據？懷疑論者還問，為什么沒有外星人訪問地球的明顯證據。我們已經發射了速度不快、規模適度的星際宇宙飛船。一個比我們先進的社會，理應能夠即便不是毫不費力地至少也是很方便地在星際間的太空中航行。經過數百萬年，這些社會理應已經建立起殖民地，他們自身或許就在進行著星際探索。為何他們卻沒有到我們這兒來？于是很可能便推斷出：地球外的天體中頂多存在著幾個發達的文明社會罷了——這樣說，或者是因為，統計結果表明，我們就是這第一批出現的技術文明社會之一;或者是因為，所有這類文明社會的共同遭遇是，他們早在發展得遠遠超過我們之前就自行毀滅了。
