在很早的时候,人们普遍地相信他们的行星——地球——是人类文明的所在地。天地万物对它怀着敬意。然而,某些早期的思想家勇敢地提出:生命不可能是独一无二的;正如伊壁鸠鲁学派的哲学家曹经写过:“在无边无际的空间,把地球看作唯一的居住世界,就象在一块田野里播种谷子,断定只有一颗颗粒生长出来一样地荒唐。”在文艺复兴时期后,广泛流传着地球外存在着文明世界的各种信念。但是直到二十世纪初期,许多综合意见再次认为在地球外寻找生命的机会是微不足道的。可是过去几十年来科学技术显著的发展才有可能对这题目找到新的途径。可能性的估计在我们银河系出现先进技术文明世界的可能性——使用通常可以得到的方法来确定它的唯一存在——取决于考虑几种不能断定的参量。在1960年美国天体物理学家费兰克·德拉克(Frank Drake)用下面通常被称为“绿岸”(Green Bank)的公式来探讨这问题:N=R_*f_pn_ef_1f_if_cL。字母N是一未知量,目前存在在银河 At a very early age, people generally believed that their planet, the Earth, was where human civilization was located. All things in the world respect it. However, some early thinkers argue bravely that life can not be unique; just as Epicurean philosophers wrote: “In the boundless space, seeing the earth as the only living world, Sowing millet in a field, concluding that only one particle grows absurdly. ”After the Renaissance, widespread belief in the existence of a civilized world outside the Earth was widespread. But it was not until the early twentieth century that many of the general comments once again assumed that the chance of finding life outside Earth was negligible. However, the remarkable development of science and technology in the past few decades has made it possible to find new ways to solve this problem. The possibility of estimating the probability of an advanced technological civilized world in our galaxy, using the methods that are usually available to determine its unique existence, depends on the consideration of several parameters that can not be determined. In 1960, American astrophysicist Frank Drake explored the problem with the following formula, commonly known as Green Bank: N = R_ * f_pn_ef_1f_if_cL. The letter N is an unknown quantity that currently exists in the Milky Way