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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，有迹象表明，在不远的将来，人们会作出更大的努力。此外，与无线电技术获得十分可观的进展相一致的是，无论是在科学界还是在社会上，人们对地球外天体中的生命这一整个课题的重要性的认识，有了极大的提高。这种新的态度的明显标志，是"海盗"号火星探测器的发射。这些发射很大程度上是用来搜寻另一颗行星上的生命的。
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.
不过，随着人们倾注越来越多的精力认真进行探索的时候，出现了一种稍带否定意味却又是很有趣的调子。几位科学家近来问了一个奇怪的问题：如果地球外的天体中存在着许多具有高度智慧的生物，那么为何我们迄今尚未能见到足以表明他们存在的证据？怀疑论者还问，为什么没有外星人访问地球的明显证据。我们已经发射了速度不快、规模适度的星际宇宙飞船。一个比我们先进的社会，理应能够即便不是毫不费力地至少也是很方便地在星际间的太空中航行。经过数百万年，这些社会理应已经建立起殖民地，他们自身或许就在进行着星际探索。为何他们却没有到我们这儿来？于是很可能便推断出：地球外的天体中顶多存在着几个发达的文明社会罢了——这样说，或者是因为，统计结果表明，我们就是这第一批出现的技术文明社会之一;或者是因为，所有这类文明社会的共同遭遇是，他们早在发展得远远超过我们之前就自行毁灭了。
