What an interesting and exciting thought. 这种看法多么有意思，多么激动人心。

We may be only one of millions of advanced civilizations. 我们也许只是几百万个高等文明社会中的一个。

Unfortunately, space being spacious¹, the average distance between any two of these civilizations is reckoned to be at least two hundred light-years, 不幸的是，空间浩瀚，据测算，任何两个文明社会之间的平均距离至少在200光年。

which is a great deal more than merely saying it makes it sound. 为了让你有个清楚的概念，光这么说还不行，还要作更多的解释。

It means for a start that even if these beings know we are here and are somehow able to see us in their telescopes, 首先，这意味着，即使那些生物知道我们在这里，而且能从望远镜里看到我们，

they're watching light that left Earth two hundred years ago. 他们所看到的也只是200年以前离开地球的光。

So they're not seeing you and me. 因此，他们看到的不是你和我。

They're watching the French Revolution and Thomas Jefferson and people in silk stockings and powdered wigs² 他们看到的是法国大革命、托马斯·杰斐逊以及穿长丝袜、戴假发套的人

people who don't know what an atom is, or a gene, 是不懂得什么是原子或什么是基因的人，

and who make their electricity by rubbing a rod of amber³ with a piece of fur and think that's quite a trick. 是用一块毛皮摩擦琥珀棒生电、认为这挺好玩的人。

Any message we receive from them is likely to begin "Dear Sire," 我们收到这些观察者发来的电文，很可能以"亲爱的大人"开头，

and congratulate us on the handsomeness of our horses and our mastery of whale oil. 祝贺我们牵着骏马，能够熟练地使用鲸油。

Two hundred light-years is a distance so far beyond us as to be, well, just beyond us. 200光年是如此遥远的距离，我们简直无法想像。

So even if we are not really alone, in all practical terms we are. 因此，即使我们其实并不孤单，实际上我们还是很孤单。

Carl Sagan calculated the number of probable planets in the universe at large at 10 billion trillion 卡尔·萨根推算，宇宙里有可能存在生命的行星多达100万亿亿颗

a number vastly beyond imagining. 这个数字远远超出我们的想像力。

But what is equally beyond imagining is the amount of space through which they are lightly scattered⁴. 但是，同样超出我们想像力的，是它们所散落的宇宙的范围。

"If we were randomly⁵ inserted into the universe," Sagan wrote, "要是我们被随意塞进宇宙，"萨根写道，

"the chances that you would be on or near a planet would be less than one in a billion trillion trillion." "你在一颗行星上或靠近一颗行星的可能性不足十亿亿亿亿分之一

That's 1033, or a one followed by thirty-three zeroes. "Worlds are precious." 即10－33。世界是很宝贵的。"

Which is why perhaps it is good news that in February 1999 the International Astronomical⁶ Union ruled officially that Pluto⁷ is a planet. 因此，这也许是好消息：1999年2月，国际天文学联合会正式裁定，冥王星是一颗行星。

The universe is a big and lonely place. We can do with all the neighbors we can get. 宇宙是个又大又寂寞的地方。我们能有多少个邻居就要多少个邻居。