寻找地外生物

FOR five decades astronomers have searched the vast ocean of space in the hope of picking up some kind of radio message from the neighbours. That nothing has been found has not deterred the search for extraterrestrial intelligence, or SETI to the cognoscenti. Despite those years of effort, SETI has done little more than dip a glass into the cosmic ocean, having looked closely at only 750 of the Milky Way’s billion or so star systems.

过去的50年间,天文学家们搜索茫茫星空以期从毗邻行星那得到几条电波讯号。即便一无所获还是阻挡不住寻找地外生物的脚步,或者按专家的说法SETI(Search For Extraterrestrial Intelligence, 地外生物探寻 )的脚步。忙了这么多年,却只是在宇宙中大海捞针,仅仅仔细观测了银河系中多至数十亿的行星中的750颗。

 

That will soon change. The Allen Telescope Array, a cluster of radio telescopes being built in California with SETI in mind, will dramatically speed up the rate at which such systems can be explored. On top of that, as astronomers get better at discovering planets, and find more habitable ones, the number of plausible targets for SETI will increase.

情形不久将会改变。为寻找地外生物在加州建立的一簇簇射电望远镜,艾伦望远镜阵列,将会大大加速星系间的探测速度。更为重要的是,由于天文学家发现行星手段见长,发现了更多可居住星球,探索地外生物的可用目标将会增多。

 

Until recently, SETI has been uncontroversial. What could be more wholesome than answering the question of whether humans are alone in the universe? A SETI subcommittee within the International Academy of Astronautics (IAA), a scientific lobby group, even fashioned a protocol on how to respond if a signal from aliens is received. This concludes by saying that no reply should be sent until appropriate international consultations have taken place. Mazlan Othman, the head of the UN’s Office for Outer Space Affairs (yes, there really is one) has suggested that her agency is “ready-made” for such co-ordination—leading one newspaper to dub her the “alien ambassador”.

直到最近,SETI变得不再富有争议。比人类在宇宙中是否孤独物种这一问题更为全面的回答会是什么?SETI的分会兼科学界游说组织,国际航空学协会(International Academy of Astronautics, IAA)甚至制定出如何回应外星人讯号的协议。协议总结为没有合适的国际间的协商,不得回应。联合国外太空事务办公室(这个是真的)的主任马自兰·奥斯曼暗示她的机构是为类似协调“提前设置”的——一家报纸由此戏称她为“外星人大使”。

 

Where things have become difficult is over whether or not researchers should be allowed to send signals into space pre-emptively, in order to attract the attention of any alien listeners who might be out there. This is called active SETI, or METI, where the “M” stands for messaging. Attempts to draft a second SETI protocol to deal with this foundered several years ago, and the chairman and two members of the IAA’s committee resigned.

争议集中的地方是研究人员是否被允许预先向外星人发送信息,以便吸引任何可能存在的外星人。这被称为主动外星生命探寻(active SETI),或 METI,“M”指信息(Messaging)。几年前草拟第二版协议的企图失败,国际航空学协会的主席和几个成员辞职。

 

The acrimony was aired on October 4th at a meeting organised by the Royal Society at Chicheley Hall, in Britain. Those opposed to METI argue that broadcasting signals into space announcing the location of Earth is tantamount to ringing a dinner gong for any carnivorous, colonising or anti-social aliens who might be listening. Although Earth would be a rather long way to go for lunch, the argument is that the decision to take such a risk is not one for a handful of scientists.

各中讥讽在英国10月4号由皇室组织,奇切力厅召开的大会上变得家喻户晓。反对METI的人们称向太空发电波报告地球的位置无异于向食肉、殖民、反社会的外星人敲用餐锣。尽管外星人到地球吃午饭实在很远,问题是冒这个险不是几个科学家说了就算。

 

Alexander Zaitsev, chief scientist at the Kotelnikov Institute of Radio Engineering and Electronics, disagrees. Dr Zaitsev has access to one of the world’s most powerful radio transmitters, the Evpatoria, and he has already sent a number of “hello” signals to nearby star systems. He argues that radar astronomy, which is used to probe things like asteroids and the surface of Venus, already gives off signals that could be picked up by aliens. He is also on record, though, as saying that humans have a moral obligation to announce their presence.

Kotelnikov无线电和电子学院亚的首席科学家,历山大扎·伊采夫,表示异议。伊采夫博士能使用世界上最强力的无线电传输器——叶夫帕托里亚(Evpatoria),而且他已经向邻近的星系发送了“你好(Hello)”的信息。他称雷达天文学在用于探测例如小行星和金星表面时,就已经传递了外星人可能接受到的信号了。但是他因为说人类有道德义务宣布自己的存在,而被备了案。

 

Even without the intervention of people like Dr Zaitsev, that may already have happened—if anyone is listening. Some people think signals emitted by television and radio stations would be detectable from nearby stars, thus rendering the debate irrelevant. Indeed, some at the meeting argued that if aliens were to use an astronomical phenomenon called gravitational lensing (in which the gravitational field of the sun bends and amplifies radio waves and light from Earth), human signals could be amplified to the point where even the light from cities would be visible.

甚至没有像伊采夫这样的人的干扰,事情也可能早就已经发生了——如果智慧生物真的在听。有些人认为由电视和广播电台发送的信号在附近星球是能探测到的,因此是争辩显得毫无作用。的确,大会上有人说如果外星人使用一种叫做重力透镜(太阳的重力场弯曲放大来自地球的无线电信号和光线)的天文现象,人类的信号可以被放大到一定程度使得城市的光线都可见。

 

Michael Michaud, who resigned as chairman of the IAA’s SETI group in 2007, said that METI is not science but rather “an attempt to provoke a reaction”. He wants wider consultation. Seth Shostak, the group’s current chairman, disagrees. He says consultation does not guarantee a “correct” answer; it seeks merely to “spread the blame if Earth gets wiped out”—though who would be left to point the finger is unclear. He also says that because there is a small but real risk to sending messages, any international consultation would be likely to conclude that the broadcasters should “shut up”.

迈克尔·米乔德作为国际航空学协会的“主动探寻地外生物”项目主席,于2007年辞退,他说“主动探寻地外生物”项目不是科学而是“挑衅的举动”。 他希望有更广泛的商议。赛斯肖·斯塔克是现任主席,他表示不同意。他说商讨不能保证得到“正确的”答案;它仅仅是“如果地球被铲平了的一个出气筒”——但是谁会生存下来指指点点还不清楚。他还说由于发送信息的危险很小却极有可能,任何国际商议的结果都会是传送站被“关掉”。

 

David Brin, an author of science fiction who also resigned from the SETI group, accused it of attempting to stage-manage the discussion. He said that those proposing METI should involve more of humanity in the debate and must accept that a moratorium may be necessary. But he is also realistic. In the not too distant future, he thinks, so many people will have the power to send signals into space that it will not be possible to control intergalactic messaging. If that turns out to be true, then hope it is ET listening, not the Daleks.

大卫·布林,一部科幻小说的作者,同样从“主动探寻地外生物”辞职,指则其密谋策划辩论。他说这些挨提建议的“主动探寻地外生物” 应该组织更人性化的讨论,并且必需接受讨论中止的必须性。但他还是很现实的。在不久的未来,他认为,有能力向太空发送信号的人们将会非常多,根本没法控制银河间信息传送。假如那成为可能,我们希望是ET收到信息,而不是达雷克斯(达克雷斯 Daleks是根据英国科幻小说改编电视剧《谁人博士Doctor Who》里的宇宙变异种族——译者注)。

 

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