The question of extraterrestrial civilizations seems to me entirely open. Personally, I think itfar more difficult to understand a universe in which we are the only technological civilization, or one of a very few, than to conceive of a cosmos brimming over with intelligent life. Many aspects of the problem are, fortunately, amenable to experimental verification. We can search for planets of other stars, seek simple forms of life on such nearby planets as Mars, and perform more extensive laboratory studies on the chemistry of the origin of life. We can investigate more deeply the evolution of organisms and societies. The problem cries out for a long-term, open-minded, systematic search, with nature as the only arbiter of what is or is not likely.
我以为地球外文明社会的问题，是个完全有待于探讨的问题。在我个人看来，那种认为宇宙间只存在我们这个唯一的技术文明社会，或者我们仅是极少数几个文明社会之一的看法，与将宇宙看成充满有智慧的生命的观点相比，更难以令人接受。幸运的是，这个问题的许多方面可以经过实验来澄清。我们可以搜寻别的恒星的行星，可以寻找像火星这样距离较近的行星上的简单生命，也可以在实验室内对生命起源的化学过程进行广泛研究。我们可以更深入地调查有关生物和社会的进化情况。总之，十分有必要就这个问题开展一项长期的、不带成见的、系统的探索研究。对于什么是可能的和什么是不可能的，唯一的仲裁者是大自然。