寻找外星人
The optimistic gamble
一场乐观的博弈
A bold new programme financed by a Silicon Valley tycoon will revitalise the hunt for alien civilizations
一项由硅谷大亨资助的崭新而大胆的项目将重启对外星文明的搜寻
Jul 25th 2015 | From the print edition
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· 译者：梓轩
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Be seeing you...
IN 1959 a young astronomer called Frank Drake was working at the Green Bank radio observatory in West Virginia. Thinking about the capabilities of the 26-metre dish under construction there, he realised that, if it were used to transmit radio waves rather than to receive them, it would produce a signal that a similar telescope on a planet orbiting another star would be able to pick up. For the first time, human beings had a technology for communicating with other solar systems—an idea which led immediately to the speculation that, if there were any aliens out there, they might already be doing something similar.
1959年，一个名叫法兰克·德雷克的年轻天文学家在（美国）西弗吉尼亚的绿岸国家射电天文台工作。他在思考一架口径为26米的在建射电望远镜的性能时，突然想到，如果用它传送而不是接收无线电波，就能够发出信号，若太阳系以外的星球上也有相似的设备，这个信号就可以被接收到了。这是人类有史以来第一次，拥有了能与其他“太阳系”取得联系的技术——这个想法一经提出便立即引起推测：如果真有外星人，他们或许也做过与此类似的尝试。
Dr Drake put his idea to three colleagues over burgers at a nearby diner. Two were distinctly unimpressed. The third, a physicist of far-reaching interests called Lloyd Berkner, was enthusiastic. And since Berkner—who had a reputation as an “optimistic gambler” a physicist of far-reaching interests, Dr Drake recalled in his memoirs—was the one who controlled the money, Dr Drake got to carry out his search. In 1960 he spent 150 hours pointing the Green Bank telescope at two nearby stars, Tau Ceti and Epsilon Eridani, and scanning for signals. Thus began the search for extraterrestrial intelligence, or SETI.
德雷克博士在天文台附近的餐馆吃汉堡时，把他的想法告诉了三个同事。其中两个人明显不为所动，但另一位名叫Lloyd Berkner（罗伊德·伯克纳）的物理学家却表示出了满腔热情。这位兴趣广泛的物理学家有着“乐观冒险家”的名头—德雷克在他的回忆录里这样说。正因为伯克纳能够提供资金，德雷克博士才得以开展他的搜寻工作。1960年，他花了150个小时用绿岸射电天文望远镜对准两颗恒星，鲸鱼座T星和波江座ε（这两颗恒星与太阳类似，而且距地球相对较近——译者注）并扫描信号。从此启动了“搜寻地外文明计划”，即SETI。
Five and half decades on, Dr Drake joined Stephen Hawking, a physicist, and Martin Rees, Britain’s Astronomer Royal, to launch Breakthrough Listen, the latest incarnation of the search. It is an undertaking that would have seemed unbelievable back then. As of 2016, an unprecedented 15% of the observing time at Green Bank’s latest dish—which at 100 metres across has 15 times the area of its first—will be devoted to seeking signals from aliens. Rather than looking at just two stars, Breakthrough Listen will observe the nearest 1m, as well as looking more generally in the core and disc of the Milky Way, and 100 other galaxies to boot. Later in 2016 the project will add the 64-metre dish at the Parkes Observatory, in Australia, to its workforce. In time, further observatories will be pressed into service. Back in 1960, Dr Drake could listen in to just one radio channel at a time. The new effort will use cutting-edge electronics to scan some 10 billion simultaneously.
五十五年以后，德雷克博士联合物理学家Stephen Hawking（史蒂芬·霍金），以及英国皇家天文学家Martin Rees（马丁·里斯），开启外星文明探索的新计划——“突破聆听”。这个计划在当年是不可想象的。2016年，绿岸射电天文望远镜将前所未有地用15%的观测时间于寻找地外生命信号。这架望远镜是最新的设备，拥有100米的口径，比之前所能观测到的区域大15倍。与之前只对两颗恒星进行观测的SETI相比，“突破聆听”将观测离地球最近的一百万颗恒星，更广泛地观测银河系的中心和整个银道面，以及银河系之外的100个星系。该计划还将于2016年投入使用澳大利亚帕克斯天文台直径为64米的射电望远镜，适时其它天文台也有可能加入观测。1960年，德雷克博士只能一次听一个无线电频道，而这项新计划将使用尖端电子设备来同时扫描100亿个无线电频道。
Many such searches, most privately funded, have been attempted before. But Breakthrough Listen will have 50 times the sensitivity of any previous effort, will cover much more of both the sky and the radio spectrum, and will also use an optical telescope to search systematically for laser transmissions, should they turn out to be E.T.’s preferred mode of discourse. All of the petabytes of resulting data will be freely available for anyone with an internet connection to analyse. The team behind Breakthrough Listen says it will do as much searching every day as any of the previous projects managed in a year.
先前也开展过许多类似的地外文明搜寻项目，它们大多由私人资助。但是“突破聆听”的灵敏度将比之前的任何一次项目高50倍，并将覆盖更广的天空和无线电频谱，同时使用光学望远镜来系统地进行激光传输搜索，以捕捉任何有可能是外星人发出的对话信号。所有生成的数据都将面向公众开放，任何人都能够用自己的电脑上网进行数据分析。“突破聆听”的工作团队说，这个项目每天所能完成的搜索任务，先前的任何一个项目一年才能完成。
Let the dice fly high
The optimistic gambler responsible for this new effort is Yuri Milner, a Russian entrepreneur and investor who has made a fortune in Silicon Valley. Mr Milner has a background in physics and a long-standing interest in space. Indeed, his parents named him after Yuri Gagarin—who, in the year of Mr Milner’s birth, became the first human to orbit the Earth. In 2012 Mr Milner helped found the Breakthrough prizes, awarded to researchers who have helped answer big questions in biology, physics and maths. Convinced that the existence of extraterrestrial life is the biggest question of all, he has committed $100m over ten years to Breakthrough Listen.
投资这个新项目里的乐观冒险家是在硅谷大获成功的俄国企业家和投资家Yuri Milner,（尤里·米尔纳）。他大学攻读物理学，并一直对太空科学情有独钟。事实上，他的父母正是以Yuri Gagarin（尤里·加加林）的名字为他起名，因为在他出生的那一年，加加林成为第一个进入太空的地球人。2012年米尔纳赞助成立科学突破奖，旨在鼓励那些在生物学、物理学和数学领域取得重要成就的科学家。米尔纳认为寻找外星生命是一切学科的重中之重，因此十年间他出资1亿美元，用以支持“突破聆听”项目。
Mr Milner reckons there are three reasons why the moment is right to go big on SETI. One is that Kepler, a space telescope run by NASA, has shown that there are a lot of potentially habitable planets out there. Geoff Marcy, an astronomer at the University of California, Berkeley, who will run Breakthrough Listen, says Kepler-based studies suggest that perhaps one star in ten has planets that are “Earth-sized and lukewarm”—not obviously too massive, too hot or too cold for vaguely Earthlike life.
米尔纳认为现在是推进外星文明探索（SETI）的最佳时机，理由有三个。一是美国航空航天局（NASA）发射的开普勒太空望远镜表明宇宙中可能存在许多可居住行星。加利福尼亚大学伯克利分校的天文学家Geoff Marcy（杰夫· 马尔西）说“基于开普勒太空望远镜的研究表明，也许每十颗恒星中中就有一颗拥有“与地球大小相当且温度适宜”的行星——即体积不是太大，温度不会让类地生物感到过热或过冷。马尔西将负责“突破聆听”的计划。
The second reason is the relentless rise of signal-processing power. The ten-billion-channel system Dr Marcy is working on would have been impossible just a few years ago. That all of the resulting data can easily be made available to other scientists and enthusiastic amateurs is another sign of progress. Some 3m people already participate in the SETI@Home project, which lets people use spare computing time to sift through previous SETI data. Since the project has now linked up with Breakthrough Listen, more will surely join it. Free access to data will almost certainly generate false alarms, but Dr Marcy accepts that as part of the price of doing business.
第二是处理信号能力的不断加强。马尔西博士所操作的拥有100亿个频道的系统哪怕在几年前也是不可想象的。如今，其它科学家和其余天文爱好者都能轻易地获取所有数据，这是另一个进步的标志。三百多万人已经参与了SETI@Home的项目，该项目能够让参与者利用电脑闲置计算能力来筛选之前SETI项目获得的数据。现在这个项目已经与“突破聆听”相连接，定将吸引更多人加入。免费的数据访问不可避免会产生虚假警报，但是达尔西博士认为做事都要付出代价，这也是其中一部分。
A third motive for the push is that an unprecedented amount of time is now available on first-rate radio telescopes. Government-funded research has seen its purse-strings drawn tight recently, and instruments like that at Green Bank need new sources of income.
第三是现在一流的射电望远镜拥有充足的时间投入观测，这一点可是前所未有的。政府减少了对其出资的研究项目的经费投入，而像绿岸射电望远镜这样的仪器需要新的收入来源。而这便成为“突破聆听”的契机。
Nevertheless, hunting for aliens will always be a long-odds bet. Breakthrough Listen will surely discover some interesting pulsars, quasars and other, possibly novel, natural phenomena, but it could get through its $100m with no SETI results at all, and no clear sense of whether another $100m would be likely to change the matter. That, and the fear of ridicule from those who question the very notion of alien-hunting, has made governments reluctant to pay for SETI, despite its demonstrable appeal to many taxpayers.
尽管如此，寻找外星人总是一场胜算不大的赌博。“突破聆听”无疑会发现一些有趣的脉冲星，类星体，或者其它新奇的自然现象，但也可能在外星文明探索上一无所获，把一亿的投入全打水漂，更不知道再花一亿是否就能扭转局面。这些渺茫的胜算，加上可能遭到那些从根本上质疑寻找外星人这个想法的人的嘲笑，让各国政府不愿资助SETI，尽管它显而易见对许多纳税人充满了吸引力。
Breakthrough Listen is not the only initiative that Mr Milner has in mind. It already has one offshoot, Breakthrough Message—a competition challenging people to create a message by which humans might announce themselves to the outside world. The prize fund for that is $1m, though as yet there is no promise any message will actually be transmitted. Mr Milner thinks there is a debate to be had before deciding on such a course of action.
“突破聆听”不是米尔纳心里唯一的倡议。它还有一个名分支项目，名叫“突破信息”。该项目旨在鼓励人们创造出可以代表人类像太空传递的信息。为此设立的奖金为100万，但至今还不能确保任何信息实际上能够被传达出去的。米尔纳认为在决定对外星文明探索的行动之前应该进行一场与此有关的讨论。
And life in the universe is a question that can be approached in other ways. Mr Milner recently hired Pete Worden, a retired American air force general and an astronomer by training, to run his projects. Both at the Pentagon, where he worked on the “Star Wars” missile-defence programme, and as boss of the research centre that is home to Kepler, Mr Worden has championed small, innovative space missions. It seems likely, then, that future bids to answer Mr Milner’s questions about life in the universe will employ a more Kepler-like approach—looking for promising nearby planets from orbit. As they say in SETI circles, watch this space.
对于宇宙中有无其他生命这个问题，解答的方式不止一个。米尔纳最近聘了Pete Worden来运行他的项目。Worden既是一位退休的美国空军上将，还是以一位受过训练的天文学家。他曾在就职于美国国防部，从事“星球大战”导弹防御项目的工作，并且还是开普勒望远镜所在的研究中心的领导。他支持小型，创新型太空任务。因此，后来人在解答米尔纳关于宇宙中生命的问题时，可能会采用更像开普勒望远镜的探索方式——即在轨道上寻找地球附近可能有生命的行星。即如“搜寻地外文明计划”圈子里的人所说的，在，探索这个空间。
Note: An earlier version of this story was first published online on July 20th. It has been slightly edited for length for inclusion in the print edition.
编者按：关于此文的一篇早期版本于7月20日首先在线上发布，为收录于纸质版中，其长度做了轻微的编辑。
From the print edition: Science and technology
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