PALE BLUE DOT

----A VISION OF THE HUMAN FUTURE IN SPACE

暗淡蓝点

----探寻人类的太空家园

WANDERERS: AN INTRODUCTION

序言: 漂泊者

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献给萨姆(Sam)，

又一位漂泊者。

你们这一代人也许会看见

做梦也想不到的奇景。

序言　漂泊者

但是请告诉我，这些漂泊者是谁……?

——里尔克(Rainer Maria Rilke)《第五哀歌》(1923)

从一开头，我们就是漂泊者。我们知道在160千米(100英里)之内每棵树的位置。当果实成熟时，我们就在那里。牲畜每年迁徙，我们都跟着走。我们高兴地品尝新鲜肉食。我们中间少数人合作，靠密谋、伪装、伏击和全力进攻，完成了多数人靠单独狩猎办不到的事情。我们相互依赖。想象起来，靠我们自己单干，就和定居一样，是荒唐可笑的。

我们联合起来，保护孩子们不受狮子和狼群的侵袭。我们教会他们所需的技能和使用工具。那时和现在一样，技术是我们生存的关键。

每当干旱持续，或者在夏日天气仍令人不安地寒冷，我们便成群地迁徙——有时走向未知的土地。我们寻找更好的地方。当小小的游牧群中跟别人合不来时，我们便离开，在其他地方寻求比较友好的团伙。我们随时都可以再从头干起。

自从人类出现以来，在99.9％的时间里我们都是猎人和粮秣征集员，也是在沙漠与草原上的流浪汉。那时没有边防卫士，也没有海关官员。到处都是待开发的土地。约束我们的只是大地、海洋和天空——加上偶尔碰到的粗暴邻居。

在气候惬意食物丰盛时，我们愿意定居下来。这时不再担风险，出现了优势，也不必谨小慎微了。在最近1万年间——这在我们的漫长历史中只是一瞬间——我们已经放弃了游牧生活。我们已经栽培植物和驯养动物。在你能够轻易取得食物的时候，又何必去追捕猎物呢?

虽有种种物质利益，定居的生活仍使我们感到不安和不满足。无论在农村还呈城市，甚至在400代人之后，我们也不能忘怀过去。广阔的道路像一首几乎被人遗忘的儿歌那样，仍在柔情地召唤。我们怀着某种幻想，开发遥远的地方。我觉得，由于自然淘汰，精心培育起来的对事物的好奇心已成为我们赖以生存的基本要素。漫长的夏季、温暖的冬天、丰硕的收成、充足的猎物——哪一样都不能永久存在。我们没有能力预测未来。灾难事件惯常在我们不知不觉之中，偷偷地袭击我们。你自己的、你所在的群体的，甚至你的种族的生活，可能全靠少数不守本分的人来决定，被一种他们难以说清或理解的渴望，吸引到未曾发现过的土地或新的世界。

梅尔维尔(Herman Melville)[译者注：美国作家(1819-1891)]在长篇小说《白鲸》中，代表古往今来和四面八方的漂泊者谈到：“一种对远方事物的永恒追求使我苦恼。我喜爱去非常凶险的海洋航行……”

对古代希腊人与罗马人来说，已知的世界包含欧洲以及被缩小了的亚洲和非洲。环绕它们的是一个不可逾越的世界海洋。外出旅行可能遇到被称为野蛮人的劣等人，或遇到被叫做神的优等生灵。每棵树都有它的精灵，每个地区各有其传奇英雄。但是神灵并不太多，至少在早先大约只有几十个。他们住在山间、地下、海中或天上。他们向人们传送信息，干预人间事务，并与人生育儿女。

随着时间的流逝，人类探测的能力大幅度提高，于是令人惊奇的事情出现了：野蛮人完全能够和希腊人、罗马人同样聪明。非洲和亚洲比以往任何人想象的都要大。世界海洋并非不可逾越。对跖人①是有的。存在三个新的洲，它们在古代就有亚洲人居住，而这些情况欧洲人从不知道。还有，令人失望的是，神灵难以找到。[①“至于有对跖人的无稽之谈”，圣奥古斯丁在公元5世纪写道，“即是说在地球的反侧(我们这里日落时，那里日出)，人们用对着我们的脚走路，这根本不可信。”纵使那里有未知的大片陆地，而不仅仅是海洋，“原始的祖先只有一对，因此无法想象在那个遥远的地区还有亚当的后裔居住。”]

人类从旧世界向新世界的第一次大规模迁移，大约出现在11 500年前的最后一次冰期。当时极区冰盖扩大；导致海洋变浅，于是人们可以在陆地上从西伯利亚走到阿拉斯加。115000年之后，有人到达南美洲的南端美，即火地岛。远在哥伦布之前，印度尼西亚的英勇移民就驾着有桨的独木舟探测西太平洋；婆罗洲人移居马达加斯加；埃及人和利比亚人环绕非洲航行；而来自明代中国的一支庞大的远洋帆船队在印度洋往返航行，在桑给巴尔建立一个基地，绕过好望角，并进入大西洋。从15世纪到17世纪，欧洲的帆船发现新大陆(对欧洲人来说，无论如何也是新的)，并环绕地球航行。在18世纪和19世纪，美国与俄罗斯的探险家、商人和移民，分别向西和向东跨越两个大洲，争着奔向太平洋。无论当事人可能是如何轻率无知，这种探险与开发的热忱具有明显的存在价值。它并不局限于一个民族或种族。它是全人类所有成员共有的天赋。

自从几百万年前人类首次在非洲东部出现以来，人们已经漫游到地球各处。现在到处都有人烟：在每一个洲，在最遥远的岛屿，从北极到南极，从珠穆朗玛峰到死海，在海底，以及有时甚至在320千米(200英里)高处都有人——就像古时候传说中栖息在天穹中的神一样。

目前至少在地球的陆地区域，剩下来供探测的地方似乎没有了。探险家正成为其成就的受害者，现在只好呆在家里了。

人们的大规模迁徙——有的是自愿的，但大部分并不是——形成了人类的生存状况。今天我们中间逃离战争、迫害和饥荒的人，比人类历史上的任何时候都多。在今后几十年，随着地球上气候的演变，看来会有更大量的人因环境恶劣而逃亡。较好的地方随时会呼唤我们。在地球上，人潮仍将时涨时落。但是现在我们要去的地方已经有人定居了。别人对我们的困境并不同情，他们已经在我们之前到达那里了。

19世纪末叶，在欧洲中部辽阔的、多种语言并用的、古老的奥匈帝国的一个偏僻市镇，莱布·格鲁伯(Leib Grubcr)正在成长。在捕捞时节，他的父亲以卖鱼为业，生活是艰辛的。青年时代的莱布能够找到的唯一的正当生计，就是背人渡过附近的巴格(Bug)河。顾客不论男女，骑在莱布的背上；他脚穿珍惜的长统靴(这是他的谋生工具)，涉过河流浅滩，在对岸把他的乘客卸下来。有时水深齐腰。那里既无桥梁，也没有渡船。本来可用马匹渡河，但它们有别的用途。于是此事留给莱布和与他一样的一些年轻人去做。他们没有别的用处，找不到其他工作。这伙人在河边上闲逛，高声报价，向可能的顾客自夸他们背得多么好。他们出租自己，就像四条腿的动物。我的外祖父就是一头载重的牲畜。

我想莱布在他整个青年时代，从来不敢走出他的家乡小镇萨索(Sassow)100千米之外。但是在1904年，他突然跑到了一个新的世界——按家里的传说，这是为了逃避一次杀身之祸。他丢下自己年轻的妻子。和他的死气沉沉的小村庄相比，德国的那些大海港城市真是有天壤之别。大海何等浩瀚，高耸人云的摩天大楼以及新土地上永无休止的喧哗，对他都是不可思议的。我们对他的出走一无所知，但是找到了他的妻子采娅(Chaiya)后来出行所乘船只的船客名单。莱布有了足够的积蓄后，把她接过去了。她乘坐的是一艘在汉堡注册的巴塔维亚号船上最便宜的舱位。读到下面简短的文字记录，真令人伤心：她能够阅读或写字吗?不能。她会讲英语吗?不会。她有多少钱?我可以想象她回答“一元钱”时，是何等狼狈与羞愧。

她在纽约登陆，与莱布团聚。她只活到生下我的母亲及其妹妹，就由分娩引起的并发症死去了。在她留居美国的短短几年间，她的名字有时英语化成为克拉拉(Clara)。25年后，我的母亲生下了自己的第一个孩子{一个儿子)，她用她从来不了解的妈妈的英文名字为这个孩子取名。

我们的远古祖先观察星星；注意到有五颗星并不像所谓的“恒”星那样按刻板的方式升起和下落。这五颗星有奇特而复杂的运动。接连几个月，它们似乎是缓慢地在恒星之间游荡。它们有时绕出一个个圆圈。今天我们称它们为行星，在希腊文中这个词的意思是游荡者。我想我们的祖先只能用它表达出这样的奇特现象。

我们现在知道行星并不是恒星，而是受太阳引力束缚的其他世界。就在对地球的探测行将完成之际，我们开始认识到地球只是环绕太阳或银河系中其他恒星的不可胜数的世界之一员。我们的行星和我们的太阳系被一个新的宇宙海洋——即深不可测的太空包围起来。比起地球上的海洋来说，它们将更难逾越。

也许这话早了一点。也许还完全不是时候。但是那些别的世界——大有希望的、不知其数的机遇——正在召唤我们。

在过去几十年间，美国和前苏联取得了一些令人震惊的历史性成就——这就是对从水星到土星的所有那些光点进行仔细的近距考察，这些星体引起我们祖先的好奇心并把他们引向科学。自从1962年成功的行星际航行开始以来，我们的飞行器已经飞越70多个新世界，或者环绕它们运行，或在它们上面着陆。我们已经在游星[译者注:古代对行星的一种称呼]之间游逛。我们发现了使地球上最高山峰相形见绌的庞大火山；还在两颗行星上找到古老的河谷，令人不可思议的是一颗行星太冷，而另一颗却太热，因而都没有流水。我们的发现还有：一个巨行星的内部有容积相当于1000个地球的液态金属氢；整个儿已经熔化了的若干卫星；一个大气中有腐蚀性的酸雾缭绕的区域，甚至其高原的温度都超过铅的熔点；铭刻着太阳系激烈形成过程真实记录的古老表面；来自冥外深空的隐蔽的冰冻星体；体现出引力之微妙和谐与结构精致的环系；还有一个被复杂有机分子云环绕的星体，而在地球的最早历史时期，这些有机分子导致了生命的起源。它们都默默地环绕太阳旋转，等待着我们去探索。

我们的祖先最初思考夜空中那些游荡光点的本质时，做梦也想不到由我们发现的种种奇观。我们探索地球和人类自身的起源。通过发现其他事物以及研究与地球或多或少相似的其他行星各种可能的命运，我们对地球更加了解。每一个星体都是可爱的和有启发意义的。但是就我们所知的情况来说，它们也都是荒无人烟和贫瘠的。在那里，找不到“更好的地方”。至少目前知道的情况是这样。

在从1976年7月开始的“海盗号”遥控探测期间，从某种意义上说，我在火星上度过了一年时间。我考察了巨砾与沙丘，甚至在中午还是红色的天空，古老的河谷，高耸的火山、严重的风暴侵蚀，由薄片叠成的两极区域，以及两个暗黑的土豆形卫星。但是没有生命——没有一只蟋蟀或一片草叶；就我们确切知道的情况而言，甚至连微生物也没有。这些行星并不像地球那样被生命所美化。生命是相当稀罕的。你可以探测几十个星体，而发现其中只有一个出现了生命，并且进化和持续存在下去。

莱布和采娅的一生中在那时以前跨越过的最宽的只是一条河，但此后他们逐渐变为横渡海洋了。他们得到的最大益处是：在充满异国情调的大洋彼岸，竟有讲他们的浯言的其他人群。与他们至少有一些共同利益，甚至还有与他们休戚与共的人们。

在我们的时代，我们已经穿越太阳系，向恒星发射了4艘飞船。海王星离地球比纽约距巴格河岸远出一百万倍。但是在那些其他的世界上没有远方亲戚，没有人群，显然也没有期待着我们的生命。没有最近去的移民送信来帮助我们了解新的大陆。我们得到的只是没有知觉的、精确的自动机械使者以光速发送的数据。它们告诉我们，这些新世界并不太像我们的家园。可是我们继续寻找生灵。我们没有办法，只能这样做。生命寻找着生命。

地球上谁也担负不起太空旅行的费用，即使我们中间的首富。因此无论我们是很烦恼，或者失业了，还是应征入伍，或受到压抑，或者无论是否公正而被指控犯了罪，我们都不可能突如其来地收拾行装，飞赴火星或土卫六。谁也不会认为创办这类私人旅游业，很快就会有高额利润。如果有朝一日人们飞往其他星体，这必定是由于一个国家或国际集团相信这样做对它有利，或者对人类有利。目前有太多的迫切任务在竞争经费，不会让我们把钱花在将人送往别的星体。

这正是本书的内容：别的世界，它们上面是什么在等待我们?关于我们自己，它们会说些什么?还有，针对人类目前面临的迫切问题，是不是值得到它们那里去?我们是否应该首先解决这些问题?或者这些问题正是该去的一个理由?

就许多方面来说，这本书对人类前途都持乐观态度。乍看起来，最前面几章对我们的缺陷似乎讲得太多。但是它们为形成我的论点提供了必要的精神与逻辑基础。

我竭力为一个问题进行不只是单方面的论述。在有些地方，我好像在和自己争论。我是这样做的。想到不只是从单方面看问题的优点，我常常和自己争辩。我希望到最后一章可以阐明我的论据。

本书的提纲大致是这样的：首先我们审查在整个人类历史上广泛流传的论点，即我们的世界与人类都是独一无二的，甚至在宇宙的运转和演化中都起了核心作用。我们按最近的空间探测与发现的步伐来考察太阳系，然后评估为把人送入太空而共同提出的理由。在本书最后也是推测性最强的部分，我描绘自己对人类未来的太空家园的长远设想。

《暗淡蓝点》讲述的是对我们的坐标、我们在宇宙中地位的一种新的认识，而这种认识仍然只是缓慢地为人们所接受。当然，在我们的时代．即便这条开放的道路对我们的呼唤声变低了，人类未来的一个主要部分仍会远在地球之外。

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转自 <暗淡蓝点：探寻人类的太空家园>

出版社: 上海科技教育出版社

出版日期: 2000-10

作者: [美] 卡尔·萨根

译者: 叶式煇、黄一勤

2000 上海科技教育出版社

FOR SAM

Another wanderer,

May your generation see

Wonders undreamt.

WANDERERS: AN INTRODUCTION

But tell me, who are they, these wanderers . . .?

—RAINER MARIA RILKE, "THE FIFTH ELEGY" (1923)

We were wanderers from the beginning. We knew every stand of tree for a hundred miles. When the fruits or nuts were ripe, we were there. We followed the herds in their annual migrations. We rejoiced in fresh meat. Through stealth, feint, ambush, and main-force assault, a few of us cooperating accomplished what many of us, each hunting alone, could not. We depended on one another. Making it on our own was as ludicrous to imagine as was settling down.

Working together, we protected our children from the lions and the hyenas. We taught them the skills they would need. And the tools. Then, as now, technology was the key to our survival.

When the drought was prolonged, or when an unsettling chill lingered in the summer air, our group moved on—sometimes to unknown lands. We sought a better place. And when we couldn't get on with the others in our little nomadic band, we left to find a more friendly bunch somewhere else. We could always begin again.

For 99.9 percent of the time since our species came to be, we were hunters and foragers, wanderers on the savannahs and the steppes. There were no border guards then, no customs officials. The frontier was everywhere. We were bounded only by the Earth and the ocean and the sky—plus occasional grumpy neighbors.

When the climate was congenial, though, when the food was plentiful, we were willing to stay put. Unadventurous. Overweight. Careless. In the last ten thousand years—an instant in our long history— we've abandoned the nomadic fife. We've domesticated the plants and animals. Why chase the food when you can make it come to you?

For all its material advantages, the sedentary life has left us edgy, unfulfilled. Even after 400 generations in villages and cities, we haven't forgotten. The open road still softly calls, like a nearly forgotten song of childhood. We invest far-off places with a certain romance. This appeal, I suspect, has been meticulously crafted by natural selection as an essential element in our survival. Long summers, mild winters, rich harvests, plentiful game—none of them lasts forever. It is beyond our powers to predict the future. Catastrophic events have a way of sneaking up on us, of catching us unaware. Your own life, or your band's, or even your species' might be owed to a restless few—drawn, by a craving they can hardly articulate or understand, to undiscovered lands and new worlds.

Herman Melville, in Moby Dick, spoke for wanderers in all epochs and meridians: "I am tormented with an everlasting itch for things remote. I love to sail forbidden seas . . ."

To the ancient Greeks and Romans, the known world comprised Europe and an attenuated Asia and Africa, all surrounded by an impassable World Ocean. Travelers might encounter inferior beings called barbarians or superior beings called gods. Every tree had its dryad, every district its legendary hero. But there were not very many gods, at least at first, perhaps only a few dozen. They lived on mountains, under the Earth, in the sea, or up there in the sky. They sent messages to people, intervened in human affairs, and interbred with us.

As time passed, as the human exploratory capacity hit its stride, there were surprises: Barbarians could be fully as clever as Greeks and Romans. Africa and Asia were larger than anyone had guessed. The World Ocean was not impassable. There were Antipodes.* Three new continents existed, had been settled by Asians in ages past, and the news had never reached Europe. Also the gods were disappointingly hard to find.

* "As to the fable that there are Antipodes," wrote St. Augustine in the fifth century, "that is to say, men on the opposite side of the earth, where the sun rises when it sets to us, men who walk with their feet opposite ours, that is on I'll ground credible." Even if some unknown landmass is there, and not just ocean, "there was only one pair of original ancestors, and it is inconceivable that such distant regions should have been peopled by Adam's descendants.''

The first large-scale human migration from the Old World to the New happened during the last ice age, around 11,500 years ago, when the growing polar ice caps shallowed the oceans and made it possible to walk on dry land from Siberia to Alaska. A thousand years later, we were in Tierra del Fuego, the southern tip of South America. Long before Columbus, Indonesian argonauts in outrigger canoes explored the western Pacific; people from Borneo settled Madagascar; Egyptians and Libyans circumnavigated Africa; and a great fleet of ocean going junks from Ming Dynasty China crisscrossed the Indian Ocean, established a base in Zanzibar, rounded the Cape of Good Hope, and entered the Atlantic Ocean. In the fifteenth through seventeenth centuries, European sailing ships discovered new continents (new, at any rate, to Europeans) and circumnavigated the planet. In the eighteenth and nineteenth centuries, American and Russian explorers, traders, and settlers raced west and east across two vast continents to the Pacific. This zest to explore and exploit, however thoughtless its agents may have been, has clear survival value. It is not restricted to any one nation or ethnic group. It is an endowment that all members of the human species hold in common.

Since we first emerged, a few million years ago in East Africa, we have meandered our way around the planet. There are now people on every continent and the remotest islands, from pole to pole, from Mount Everest to the Dead Sea, on the ocean bottoms and even, occasionally, in residence 200 miles up—humans, like the gods of old, living in the sky.

These days there seems to be nowhere left to explore, at least on the land area of the Earth. Victims of their very success the explorers now pretty much stay home.

Vast migrations of people—some voluntary, most not— have shaped the human condition. More of us flee from war, oppression, and famine today than at any other time in human history. As the Earth's climate changes in the coming decade. there are likely to be far greater numbers of environmental refugees. Better places will always call to us. Tides of people will continue to ebb and flow across the planet. But the lands we run to now have already been settled. Other people, often unsympathetic to our plight, are there before us.

LATE IN THE NINETEENTH CENTURY, Leib Gruber was growing up 111 Central Europe, in an obscure town in the immense, polyglot, ancient Austro-Hungarian Empire. His father sold fish when he could. But times were often hard. As a young man, the only honest employment Leib could find was carrying people across the nearby river Bug. The customer, male or female, would mount Leib's back; in his prized boots, the tools of his trade, he would wade out in a shallow stretch of the river and deliver his passenger to the opposite bank. Sometimes the water reached his waist. There were no bridges here, no ferryboats. Horses might have served the purpose, but they had other uses. That left Leib and a few other young men like him. They had no other uses. No other work was available. They would lounge about the riverbank, calling out their prices, boasting to potential customers about the superiority of their drayage. They hired themselves out like four-footed animals. My grandfather was a beast of burden

I don't think that in all his young manhood Leib had ventured more than a hundred kilometers from his little hometown of Sassow. But then, in 1904, he suddenly ran away to the New World to avoid a murder rap, according to one family legend. He left his young wife behind. How different from his tiny back-water hamlet the great German port cities must have seemed, how vast the ocean, how strange the lofty skyscrapers and endless hub-bub of his new land. We know nothing of his crossing, but have found the ship's manifest for the journey undertaken later by his wife, Chaiya joining Leib after he had saved enough to bring her over. She traveled in the cheapest class on the Batavia, a vessel of Hamburg registry. There's something heartbreakingly terse about the document: Can she read or write? No. Can she speak English? No. How much money does she have? I can imagine her vulnerability and her shame as she replies, "One dollar."

She disembarked in New York, was reunited with Leib, lived just long enough to give birth to my mother and her sister, and then died from "complications" of childbirth. In those few years in America, her name had sometimes been anglicized to Clara. A quarter century later, my mother named her own firstborn, a son, after the mother she never knew.

OUR DISTANT ANCESTORS, watching the stars, noted five that did more than rise and set in stolid procession, as the so-called "fixed" stars did. These five had a curious and complex motion. Over the months they seemed to wander slowly among the stars. Sometimes they did loops. Today we call them planets, the Greek word for wanderers. It was, I imagine, a peculiarity our ancestors could relate to.

We know now that the planets are not stars, but other worlds, gravitationally lashed to the Sun. Just as the exploration of the Earth was being completed, we began to recognize it as one world among an uncounted multitude of others, circling the Sun or orbiting the other stars that make up the Milky Way galaxy. Our planet and our solar system are surrounded by a new world ocean the depths of space. It is no more impassable than the last.

Maybe it's a little early. Maybe the time is not quite yet. But those other worlds—promising untold opportunities—beckon.

In the last few decades, the United States and the former Soviet Union have accomplished something stunning and historic—the close-up examination of all those points of light, from Mercury to Saturn, that moved our ancestors to wonder and to science. Since the advent of successful interplanetary flight in 1962, our machines have flown by, orbited, or landed on more than seventy new worlds. We have wandered among the wanderers. We have found vast volcanic eminences that dwarf the highest mountain on Earth; ancient river valleys on two planets enigmatically one too cold and the other too hot for running water; a giant planet with an interior of liquid metallic hydrogen into which a thousand Earths would fit; whole moons that have melted; a cloud-covered place with an atmosphere of corrosive raids, where even the high plateaus are above the melting point of lead ancient surfaces on which a faithful record of the violent formation of the Solar System is engraved; refugee ice worlds from the transplutonian depths; exquisitely patterned ring systems, marking the subtle harmonies of gravity; and a world surrounded by clouds of complex organic molecules like those that m the earliest history of our planet led to the origin of life. Silently, they orbit the Sun, waiting.

We have uncovered wonders undreamt by our ancestors who first speculated on the nature of those wandering lights in the night sky. We have probed the origins of our planet and ourselves. By discovering what else is possible, by coming face to face with alternative fates of worlds more or less like our own, we have begun to better understand the Earth. Every one of these worlds is lovely and instructive. But, so far as we know, they are also, every one of them, desolate and barren. Out there, there are no "better places." So far, at least.

During the Viking robotic mission, beginning in July 1976, in a certain sense I spent a year on Mars. I examined the boulders and sand dunes, the sky red even at high noon, the ancient river valleys, the soaring volcanic mountains, the fierce wind erosion, the laminated polar terrain, the two dark potato-shaped moons. But there was no life—not a cricket or a blade of grass, or even, so far as we can tell for sure, a microbe. These worlds have not been graced, as ours has, by life. Life is a comparative rarity. You can survey dozens of worlds and find that on only one of them does life arise and evolve and persist.

Having in all their lives till then crossed nothing wider than a layer, Leib and Chaiya graduated to crossing oceans. They had one great advantage: On the other side of the waters there would be-invested with outlandish customs, it is true—other human beings speaking their language and sharing at least some of their values, even people to whom they were closely related.

In our time we've crossed the Solar System and sent four ships to the stars. Neptune lies a million times farther from Earth than New York City is from the banks of the Bug. But there are no distant relatives, no humans, and apparently no life waiting for us on those other worlds. No letters conveyed by recent émigrés help us to understand the new land— only digital data transmitted at the speed of light by unfeeling, precise robot emissaries. They tell us that these new worlds are not much like home. But we continue to search for inhabitants. We can't help it. Life looks for life.

No one on Earth, not the richest among us, can afford the passage; so we can't pick up and leave for Mars or Titan on a whim, or because we're bored, or out of work, or drafted into the army, or oppressed, or because, justly or unjustly, we've been accused of a crime. There does not seem to be sufficient short-term profit to motivate private industry. If we humans ever go to these worlds, then, it will be because a nation or a consortium of them believes it to be to its advantage—or to the advantage of the human species. Just now, there are a great many matters pressing in on us that compete for the money it takes to send people to other worlds.

That's what this book is about: other worlds, what awaits us on them, what they tell us about ourselves, and—given the urgent problems our species now faces—whether it makes sense to go. Should we solve those problems first? Or are they a reason for going?

This book is, in many ways, optimistic about the human prospect. The earliest chapters may at first sight seem to revel overmuch in our imperfections. But they lay an essential spiritual and logical foundation for the development of my argument.

I have tried to present more than one facet of an issue. There will be places where I seem to be arguing with myself. I am. Seeing some merit to more than one side, I often argue with myself. I hope by the last chapter it will be clear where I come out.

The plan of the book is roughly this: We first examine the widespread claims made over all of human history that our world and our species are unique, and even central to the workings and purpose of the Cosmos. We venture through the Solar System in the footsteps of the latest voyages of exploration and discovery, and then assess the reasons commonly offered for sending humans into space. In the last and most speculative part of the book, I trace how I imagine that our long-term future in space will work itself out.

Pale Blue Dot is about a new recognition, still slowly overtaking us, of our coordinates, our place in the Universe and how, even if the call of the open road is muted in our time, a central element of the human future lies far beyond the Earth.

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From < Pale Blue Dot>

Publisher: Ballantine Books

Publication Date: 1997-9

BY CARL SAGAN

Copyright 1994 by Carl Sagan

卡尔·萨根:预约新宇宙 - Chapter 0