我们的梦想 keyfc天文部：如何找到一个外星人妹妹呢？

思兼SRW - 2012/8/9 23:43:00

Another reason I love astronomy: it has a good shot

at answering this question.
另外一个我喜欢天文的原因：回答这些问题很爽。
Even a few decades ago hard-headed realists pooh-

poohed the idea of aliens. But times change, and so

does science. We’ve accumulated enough data that

makes the question less far-fetched than it once

was, and I’m starting to think that the question

isn’t “Will we find life?” but rather “Which

method will find it first?”
即使几十年前，头脑冷静的现实主义者还在对有没有外星

人的想法报以呸呸的嘲笑。但是时间在变化，科学也在变

化。我们已经积攒了足够的数据让这些个问题显得不是那

么扑溯迷离。比起“我们找得到外星妹子吗？”相比，我

选择从“用怎样的方法才能找到外星妹子”
There are three methods that, to me, are the front

-runners for finding life on other worlds. And I

have an idea as to which one may find it first.
这里有三种方法，对我来说，是寻找生命世界的的领跑者

。对于哪种方法能先发现外星妹子，我也有一定的想法
Life on Mars?

The first method follows the principle that when

you’re looking for something, it’s best to start

close to home.
火星上的生命？
第一个想法就是当你想找什么东西的时候，你最好从离你

近的地方开始。
We know of one planet that has life: Earth. So it

makes sense to look for other places with Earth-

like conditions: that is, liquid water, oxygen in

the air, nutrients for growth, and so on.

我们知道一个地方有生命了，地球。于是我们从其他看上

去由液态水，大气中有氧气，氮气等像地球的星球开始寻

找。
The most obvious place to look is Mars. At first

glance it appears dry, cold and dead. But if you

can see past that, things start to look up. The

polar caps, for example, have lots of frozen water,

and we’ve directly seen ice at lower latitudes o n

the Red Planet as well – meteorite impacts have

left behind shiny craters, digging up fresh ice

from below the surface.
最明显的需要寻找的地方就是火星，第一眼看上去干燥寒

冷死气沉沉的星球。但是如果你能够看到这些的背后，火

星的极冠。有很多的固态水，我们在稍低纬度的地区也能

看见冰的存在。陨石冲击留下的闪光的陨石坑正是从表

层以下外出了新鲜的冰。

Several Mars rovers and landers have uncovered

tantalising evidence that liquid water might flow

just beneath the surface, but we still lack any

conclusive evidence. However, if you broaden your

timescale a bit, there is excellent evidence that

in the past – perhaps a billion years or so ago –

our neighbouring planet had oceans of liquid water

and thicker air. In fact, conditions were pretty

good to develop life as we know it even before it

popped up here on Earth.
一些火星探测器发现了液态水曾经存流经表面的迹象，但

是我们仍然缺乏一些决定性的证据。如果你扩大你的时间

尺度一点，在过去就有极佳的证据---可能是数十亿年前。

我们的邻居星球曾经有液态水和稀薄的空气。实际上据我

们所知，比起那时地球来说，对于出现生命这是非常适合的

环境。
It’s entirely possible that life got a toehold (or

pseudopod hold) there long ago, and died out. If

that’s the case, we may yet find fossils in the

Martian rocks. Again, there’s no conclusive

evidence yet, but we’ve literally barely scratched

the surface there. Now that it has successfully

landed on Mars, we have the exciting possibility

that the plutonium-powered, car-sized Curiosity

rover will soon use its on-board laser and other

tools to crack open and examine rocks in the Gale

Crater, which were laid down billions of years ago

in the presence of liqui d water.
很久以前生命存在，然后灭绝是完全有可能的。如果是

这样我们完全有可能在这片曾经是水下火星的岩石中发现化石，好吧，虽

然我们没有确凿的证据。但我们仅仅是是挠了火星的表面

一下而已。但这是这次，一辆车大小的探测器很快将会用

自带的激光器和其他工具打碎这些数十亿年前在液态水下

的岩石。

And Mars isn’t the only possibility in our solar

system. Liquid water exists inside Saturn’s moon

Enceladus, where geysers of liquid water erupt from

deep canyons at its south pole. Energised by the

gravitational tug of the giant ringed planet

itself, the interior of Enceladus may be a vast

ocean of liquid water even while the surface is

frozen over. That doesn’t guarantee we’ll ever

find alien fish swimming that moon’s seas, of

course. But it’s an interesting place to look.
火星并不是太阳系的唯一可能。液态水也在土卫二出现过

，在南极的深深的峡谷里，有出现液态水的喷泉。由于土

星的重力拖拽的能量，尽管表面有可能结冰，土卫二内部

可能充满了液态水的海洋。这不能保证我们能找到外星鱼

在里面游，但这确实是一个可以围观的有趣的地方。
Europa, a moon of Jupiter, almost certainly has an

undersurface ocean as well. If you relax your

constraints even more, Saturn’s moon Titan has

lakes of liquid methane and ethane on its surface,

too. The chemistry for life would be different

there – it’s a rather chilly -180C on the surface

– but it’s not impossible to suppose life might

arise there too.
阿鲁巴……不欧罗巴，也就是木卫二木星的卫星，几乎

已经确定了存在了底下海。如果你再放开你的限制，土卫

六由液态的甲烷和乙烷的湖泊。和生命有关的化学活动將

會有所不同，相当的冷有-180摄氏度。但是这也不足以否

认生命的可能性。

Finding out whether this is the case means getting

up close and personal. We’re doing that for Mars;

however, the likes of Europa and Enceladus may have

to wait a decade or four.
要查明这些就要靠我们自己去了。这恰好是我们在火星上

干的事情。至于土卫四和木卫二，恐怕还要等20年或者40

年。
Phone home

But maybe we don’t have to go anywhere. Instead,

we might be able to sit here and wait for alien

beings (of whatever form) to message us.
在家等电话

等等我们可能那里也不用去，相对的我们可以坐在那里等

外星人妹妹（或者其他形式）给我们个信息。
====

SETI is the Search for Extraterrestrial

Intelligence, and its name tells you its story: it

’s a group of astronomers looking for signs of

intelligent life in space. They use various methods

to look for advanced aliens, but the most promising

one is to listen for any messages sent across the

skies.
SETI（Search for Extraterrestrial Intelligence）就

在干这个事情。一群天文学家寻找着可能从智慧生命过来

的信号。他们使用各种各样的方法寻找进化的外星生命。

但是最有希望的一种就是监听穿梭与天宇之间的的信息。
The basic SETI assumption is that aliens are out

there and want to contact us. If that’s the case,

there’s a good way they can signal us: radio

waves. They’re the perfect medium: they’re cheap,

easy to make, easy to encode with information, they

travel across the whole galaxy unimpeded, and they

move at the speed of light, the fastest thing we

know. So SETI scours the skies looking for radio

signals from ET.

SETI的基本假设是外星人就在那里并且想联系我们。如果

这样，用无线电波给我们发信号算个好办法。媒介非常完

美，他们经济，易于掌握，易于编码传送信息，并且在银

河畅通无阻。他们以我们已知最快的速度---光速前进，所

以SETI45度角仰望天空，等待着妹子从那里传来的信号。
They haven’t found anything yet, but as SETI

astronomer Seth Shostak points out, we’ve just

started looking. There’s a lot of galaxy and a lot

of radio wave frequencies to sift through. But our

technology gets better all the time, allowing for

more sensitive searches. According to Shostak, if

they’re out there and currently sending signals

our way, we should have an answer one way or

another in about 25 years given the way things are

going.
目前他们还没找到任何东西。不过SETI的天文学家Seth

Shostak之处，我们才刚刚启程。还有很多星系的无线电波

等待着我们的筛选。毕竟我们的科技在不断成长。让搜索

的灵敏度变得更高。如果他们确实在哪里，并且目前正在

像我们传送信息，并且等我们收到信息在发送出去，这大

概需要25年。
I think SETI is a good idea. In a practical sense

their engineers are advancing our radio technology

and signal processing, and philosophically I think

it’s interesting to listen for alien signals. But

I do wonder about the basic assumption that aliens

are out there and want to contact us – it’s a big

leap, and based on our own human motivations. So

while this is certainly worth the effort, it’s

hard to know if it’ll pay off, and the 25-year

deadline reflects that.
我觉得SETI是个好主意。实际意义上SETI的工程人员正在

提升我们的无线电和信号处理技术。并且在哲学上，倾听

外星信号也是一个很有意思的行动。虽然我不知道外星人

会不会就在那里，并且想要联系我们。这是一个大漏洞，

这些都是基于这些人类的行动。这些值得的。
But I suspect another method may have the edge.
我怀疑另一个方法有搞头
New world order
新的世界法则

For a long time, we only knew of nine planets

(including Pluto, though this was downgraded from

its planet status five years ago), and only one

that could support life. Then, in 1995, astronomers

found the first planet to orbit another sun-like

star. The planet wasn’t like ours at all – more

massive than Jupiter, and orbiting so close to its

parent star its temperature is over 1,000C. But it

was a watershed moment. We finally knew that other

planets exist.
在很长的一段时间里，我们只知道九大行星，包括冥王

星，虽然5年前被开除学籍了。只有一个能够支持生命，呢

么1995年天文学家发现了另一个星球轨道上发现了一个非

常类似太阳的行星，这个行星完全不像是地球，比木星质

量更大，并且轨道更近，以至于表面温度有1000摄氏度。
但是这是一个转折点。我们终于知道了了其他星球的存在

。
Since then, Nasa’s Kepler space telescope, the

European Space Agency’s Corot mission and ground-

based instruments have found nearly 800 other

planets, and that number grows every week. We know

of enough planets orbiting other stars that we can

actually start to extrapolate some numbers: it

looks like approximately half of all stars in the

galaxy have planets, and planets may in fact

outnumber the 200 billion stars in the Milky Way.
从那时起位于欧洲航天中心Corot计划任务，NASA的开普勒

望远镜，以及地基仪器，已经发现了800个这样的星球。并

且这个数字每个星期都在增长。我们已经知道足够多的轨

道类似地球星球，于是我们可以推断一些数字，这个看上

去一般银河系的恒星都有行星。在银河系里，这样的醒醒

的实际数量可能超过2000亿。
We still don’t know how many of these worlds are

like ours, but it seems like it’s a good bet the

number is in the million, if not billions. We’re

finding smaller and smaller planets all the time,

and statistically speaking Earth-sized planets

should be fairly common.
我们还不知道这样的世界有几个是和我们一样的，不过看

上去打赌有100万个是个不错的主意。我们每时每刻都在妨

碍西安一些更小更小的行星。统计学家说，地球大小的行

星很常见。
The big question is how many of these have life? We

don’t know. But consider this: we have evidence

that life on Earth started almost immediately after

its surface was cool and stable enough to allow it.

For three billion years that earthly life consisted

of one-celled organisms, and it’s only relatively

recently that these evolved into the type of multi

-celled creatures that now inhabit every niche of

this blue planet.
问题是这里面有几个有生命呢，啊哈哈佐由里不知道。但

是想想这个，我们有证据标明地球在冷却和固化后生命立

刻就出现了。30亿年，从单细胞生物有机物，到多细胞生物，直到今天充满世界每个角落。
It means that any Earth-like planets we find may be

populated by… yeast. But that counts. It’s life.

And life does something special: it ingests

chemicals and excretes other chemicals.
这意味着我们找到的类地行星可能充满了……酵母，这个可以有，因为这个算是生命，然后生命做一些特别的事情，它摄取化学物质，产生其他的化学物质。
Tell-tale signs
一些标志
One such chemical is oxygen. On Earth, we breathe

it in, but plants breathe it out. There’s a lot of

it in our air; our atmosphere is more than 20%

oxygen. If we found a planetary atmosphere with

lots of oxygen gas, that would almost certainly be

an indicator of life.
===
其中一种化学元素，氧气。在地球上我们吸氧气，植物排氧气。大气含量中有相当的氧气成分。大约20%，也就说我们大概可以说要是空气中氧气含量很高，那么就很可能存在生命。
As it turns out, we’re on the verge of being able

to do just that. Planets are dim and huddle close

to their stars, but there are techniques to

separate the light from the two objects. Oxygen has

a signature, like a fingerprint, that can be

detected in that light. It will take an extremely

sensitive telescope and very clever techniques to

see it, but we have the technology now to build

such machines. One such is the James Webb Space

Telescope, due to launch in 2018. It should be able

to detect oxygen in an alien planet’s air. And

many other instruments are being planned and built

that can carry out similar observations.
我么几乎可以测量了，氧气有特征光谱，和指纹一样
我们可以通过光谱分系发现其他星球中的气体成分，尤其是氧气。
Our technology is getting so good so quickly that

finding alien biological atmospheric signatures is

probably our best bet. To me, the numbers add up

better than for the other strategies: there must be

lots of this type of planet out there, life seems

to arise easily, and biology messes with a planet’

s chemistry in a detectable way. We don’t know if

Mars or those watery moons have life at all, and

even if they do it could take a long time to find

it. And who knows if smart aliens are out there,

and want to talk to us? But it may only be a few

more years until we point a telescope at a fleck of

light, absorbing those photons one by one, sifting

through them, and finding in them – literally –

the breath of life.
我们的科技在快速进步，气体分析是最好的途径。既然可以探测气体环境，对于我来说，这些数字一定比其他方法要好得多，那里肯定有很多这样的行星，生命很容易出现。然后创造出用生物学和星球化学成分的检测手段。我们不知道火星和哪些充满水的卫星是否存在生命，如果有，发现他们也会消耗很多时间。谁会知道那里会不会有智慧的外星人等在哪里想和我们说话呢，但是这可能只需要我再过一些年我们的望远镜指向一束斑驳的光线，一个个接受着哪里的光子，筛选他们，最后找到他们，字面意义上的，生命的气息。
So when will we find life in space? If it's out

there, then my hope is: very soon.
所以我们啥时候才能找到？
如果他们就在那里，我的愿望是：很快。

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