MOUNTAIN VIEW, Calif. — For more than a half-century, a small group of astronomers¹ has sought intelligent company among the stars. They’ve done so by turning large radio antennas³ skyward, hoping to eavesdrop⁴ on signals from an advanced society. It’s a program known as SETI, the Search for Extraterrestrial Intelligence.

加利福尼亚山景城——半个多世纪以来，一些天文学家一直在探寻星际中的智慧生命，探寻我们的同伴。他们为此架设朝向天空的大型无线电天线，以期捕获来自科技先进的世界的信号。人们称这一探索计划为“地外文明搜寻计划”（Search for Extraterrestrial Intelligence，简称SETI）。

But now some researchers propose that we should do more than simply don headphones and await E.T.’s call: We should make serious efforts to encourage a response from putative⁵ aliens by deliberately⁶ transmitting our own messages. It’s a simple idea, akin⁷ to tossing a bottle into the cosmic ocean. But recent arguments for what’s termed active SETI have loosed a storm of controversy⁸, one that has even washed into the halls of academe.

不过，现在有一些研究者建议，我们不能只是侧耳倾听，等待外星人的召唤，而要做更多、更积极的努力，主动传递出自己的信息，鼓励可能存在的外星人做出回应。这是个简单的想法，如同向浩瀚的宇宙扔一只瓶子。不过最近，被称作“主动探寻地外文明”的想法引发了诸多讨论，刮起了一场争议的风暴，甚至蔓延到了学术界。

Why is this? Why has the sending of dispatches to worlds many trillions of miles distant suddenly become a hot-button issue? The simple answer is that there’s now a perception that advertising⁹ our existence could be a mortal threat to the planet.

这是为什么呢？为什么向远在万亿英里之外的世界发送信息会骤然成为热点话题？答案很简单，因为现在有一种看法认为，广泛宣示人类的存在可能会对我们的星球造成致命威胁。

The reasoning is this: While no one has yet offered decisive proof for life beyond Earth, in the past two years astronomers have learned that tens of billions of habitable planets suffuse¹⁰ our galaxy¹¹. Consequently, to believe that only Earth has spawned¹² intelligence is to insist that our world is the site of a miracle. That point of view rarely appeals to scientists.

原因在于：尽管尚未有人能给出存在地外生命的确凿证据，但过去两年间，天文学家们了解到，我们的银河系遍布着数以百亿的宜居星球。因此，让人相信只有地球产生了智慧生命就等于坚持认为我们生活的世界全然是一块奇迹之地。科学家不喜欢这种假设。

The aliens could very well be out there. And that realization¹³ has spurred a call by some for broadcasts intended to elicit¹⁴ a communication from at least the nearest other star systems. But we know nothing of the aliens’ possible motives¹⁵ or behavior. Therefore, it’s conceivable that betraying our existence might prompt aggressive action from space.

地球以外很可能存在外星人。这种认识引起一些人呼吁发出广播信号，意在引发至少与最近星系的交流。不过，我们对外星人的动机和行为一无所知。因此可以想像，泄露人类的存在可能会激起来自太空的侵略行动。

Broadcasting is likened to “shouting in the jungle” — not a good idea when you don’t know what’s out there. The British physicist¹⁶ Stephen Hawking¹⁷ alluded¹⁸ to this danger by noting that on Earth, when less advanced societies drew the attention of those more advanced, the consequences for the former were seldom agreeable.

向地外发送广播信号就像“在丛林中大声叫喊”，如果你不知道周围存在着什么，那么这样做可能很不明智。英国物理学家史蒂芬·霍金(Stephen Hawking)便暗示过这种危险——他指出，在地球上，如果较落后社会引起了较先进社会的注意，那对前者来说很少是件好事。

It’s a worry we never used to have. Victorian-era scientists toyed with plans to use lanterns and burning pools of oil to contact postulated¹⁹ Martians. In the 1970s, NASA bolted greeting cards onto spacecraft²⁰ that will leave our solar system and wander the vast reaches between the stars. The Pioneer and Voyager probes carry plaques²¹ and records with information about what humans look like and where Earth is, as well as a small sampling of our culture.

过去，我们从来没有这种担心。维多利亚时代的科学家设想过用点亮灯盏和大量燃油的方式与设若存在的火星人取得联系。到了20世纪70年代，美国国家航空航天局将问候贺卡栓牢在航天器上，并随航天器离开太阳系、在恒星之间的广阔空间漫游。“先驱者”号和“旅行者”号探测器则携带镀金铝板和镀金铜质唱片，承载着人类长什么模样和地球位于何方的信息，还包括一个人类文化的小样本。

Those messages move at the speed of rockets. But in 1974, a three-minute encoded pictogram was transmitted using the large radio antenna² at Arecibo, Puerto Rico. It moves at the speed of light, 20,000 times faster. More recent radio transmissions include a Beatles song beamed by NASA to the North Star, a Doritos advertisement launched to a planetary system in the Big Dipper, and a series of broadcasts sent to nearby stars using an antenna in Crimea.

上述这些信息的传递速度与火箭相同。不过1974年，波多黎各的阿雷西博天文台(Arecibo)用大型无线电天线发送了一个3分钟的编码图片符号，运行速度已达光速，比之前的信息快2万倍。更近期发送的无线电信息有：美国宇航局向北极星传送的一支甲壳虫乐队的歌，向北斗星座一个行星系发送的一段“立体脆”食品广告，以及通过在克里米亚的一部天线向近地恒星发送的一系列无线电信号。

When most people believed that aliens were no more than easy black hats for Hollywood, the idiosyncratic nature of these messages could be easily dismissed. But if cosmic company is a legitimate²³ possibility, shouldn’t we offer up something more edifying²⁴ than pop music and snack food? A deliberate transmission should represent all of humanity — not short-circuit the important question of who will speak for Earth.

在大多数人认为外星人不过是好莱坞的噱头的时代，人们很容易对这些怪怪的选择不以为然。但如果真的有可能存在外星生命，我们难道不应当发送比流行音乐和小吃零食更有助益的信息吗？深思熟虑后发送的信息应当能代表全体人类——而不能回避谁可以代表地球这一重要问题。

Consequently, recent conferences on the merits of active SETI have sought the advice of social scientists. Among their worries is whether to be up front about humanity’s seamy side: Should we tell the extraterrestrials about war and injustice²⁵?

所以，最近就“主动探寻地外文明”的好处方面，有讨论会开始向社会科学家寻求意见。诸多担忧中有一条，是否要诚实展现人类丑陋的一面。我们需要告诉地外文明我们有战争和不公正现象吗？

Personally, I think this concern is overwrought. Any society that can pick up our radio messages will be at a level of development at least centuries beyond our own. They would be no more incensed²⁶ by our bad behavior than historians who learned that Babylonians attacked one another with spears. It seems naïve²⁷ to imagine that, by shielding aliens from the less flattering aspects of humanity, we would somehow lessen²⁸ any incentive²⁹ to do us harm. If there’s a danger, mincing³⁰ words is unlikely to eliminate it.

就个人而言，我认为这种担忧过虑了。能接收到地球无线电信息的社会必定处在比我们先进至少几世纪的发展水平。他们对人类的不良行为产生的愤怒不会比历史学家发现巴比伦人自相残杀更严重。认为只要对他们掩盖我们不光彩的一面，就可以降低他们加害我们的动机，这种想法似乎太天真。如果确有危险存在，我们不太可能通过文过饰非把这种危险消除。

A better approach is to note that the nearest intelligent extraterrestrials are likely to be at least dozens of light-years away. Even assuming that active SETI provokes a reply, it won’t be breezy conversation. Simple back-and-forth exchanges would take decades. This suggests that we should abandon the “greeting card” format²² of previous signaling schemes, and offer the aliens Big Data.

一种更好的做法，是先认识到离我们最近的地外智慧生命可能至少也隔着几十光年的距离。即使主动SETI的行为引起了一个回应，那也不会是顺畅的聊天。简单的一问一答也要几十年。这意味着，我们要放弃以前那种“问候卡”式的信号发送模式，向外星人发送大数据。

For example, we could transmit the contents of the Internet. Such a large corpus — with its text, pictures, videos and sounds — would allow clever extraterrestrials to decipher much about our society, and even formulate³¹ questions that could be answered with the material in hand. Sending the web on its way would take months if a radio transmitter were used. A powerful laser, conveying bits much like an optical fiber³², could launch these data in a few days.

比如，我们可以发送互联网内容。文本、图片、视频和音频汇编的大型数据库可以让聪明的外星人破解更多有关人类社会的信息，甚至思考出一些用手头资料能够解答的问题。采用无线电广播发射机传送网络信息需要几个月时间；而用强激光传送这些数据只需几天，很像用光导纤维传输。

Sending messages — even big ones — is technically³³ feasible. However, there’s still the highly controversial matter of whether to broadcast at all. Who decides? One could simply let the public weigh in, but doing so wouldn’t address the security issue. Even if a majority is comfortable with a transmission, how does that mitigate³⁴ the possible danger?

向地外传送信息乃至大量信息，从技术角度来讲是可行的。不过，要不要向地外发送信息还是一个争议极大的问题。谁来做这个决定？我们完全可以让公众参与决策，但这并不能解决安全问题。即便多数人愿意发送信息，那就能消除潜在危险了吗？

The inability to gauge³⁵ this peril³⁶ prompts some critics to argue that, given the possibly existential threat posed by active SETI, we should choose the side of caution. We should simply forbid powerful transmissions to the skies. Indeed, a small consortium of academics in California has drafted a petition urging this.

由于无法测量这种危险，一些批评者提出，考虑到主动寻找地外文明可能造成的威胁，我们宁可慎重，应当禁止向外太空进行大功率传输。事实上，加州一小部分学者已经就此起草了请愿书，呼吁这么做。

It’s a wary³⁷ approach. It’s also poor insurance. Any extraterrestrials with technology advanced enough to threaten us will surely have antennas larger than our own, instruments that can pick up the television and radio signals broadcast willy-nilly since World War II. We are already shouting into the jungle, albeit³⁸ with less volume than a deliberate signal. But the dangerous creatures may have good hearing.

这种做法虽谨慎，却也不是万无一失。技术发达程度足以威胁我们的地外文明必定拥有比我们更大的天线等强大设备，能够接收二战以来人类发送的杂乱的电视信号和无线电信号。我们已经在对着丛林大喊了，只不过音量没有主动发送的信号那么大。但危险生物的耳朵也可能很尖。

Additionally, if we forbid high-powered transmitters aimed at the sky, we shut out such obvious future technologies as better radars³⁹ for aviation and tracking dangerous asteroids⁴⁰. Do we really want to hamstring our descendants this way?

此外，如果禁止高功率设备向天空发射信号，我们显然就阻断了未来技术的发展，研制不出在航空飞行及追踪危险小行星领域性能更加优越的雷达。我们真的要就此束缚后世儿孙的发展吗？

A decision to engage in active SETI has not been made. The benefit — learning our place in the cosmos⁴¹ — is only hypothetical, and so is the danger. But I, for one, would hesitate to let a paranoia⁴² based on nothing more than conjecture⁴³ shackle⁴⁴ the activities of our children and our children’s children. The universe beckons⁴⁵, and we can do better than to declare that future generations should endlessly tremble at the sight of the stars.

是否应当开展主动SETI还没有定论。这么做的好处——了解我们在宇宙中的位置——只是一种假设，但其风险也是假设。但就个人而言，我会犹豫是否让一种只有猜想做基础的疑神疑鬼心理束缚住我们的孩子、孩子的孩子的行动。宇宙在召唤，我们应该能做得更好，而不是让未来一代人看到星星就陷入无尽的恐惧战栗中。