TED2015
Sara Seager: The search for planets beyond our solar system
莎拉·西格尔: 寻找太阳系外的行星
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我们在天空中看到的每一颗恒星都有至少一颗行星在围绕着它运行，天文学家莎拉·西格尔如是说。我们对这些外行星了解多少，又要如何发现更多这样的星球呢？西格尔介绍了她最喜欢的一组外行星，并展示了一项可以帮助我们搜集关于它们的信息——甚至可以帮助我们寻找有生命迹象的外行星的新技术。
Sara Seager - Exoplanet expert
Sara Seager’s research led to the first discovery of an atmosphere on a planet outside our solar system. Now she’s on the hunt for a twin Earth. Full bio
Sara Seager’s research led to the first discovery of an atmosphere on a planet outside our solar system. Now she’s on the hunt for a twin Earth. Full bio
Double-click the English transcript below to play the video.
00:12
I'm here to tell you
about the real search for alien life.
about the real search for alien life.
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我想告诉你们一些针对外星生命
所展开的真实的探索行动。
所展开的真实的探索行动。
不过不是那些通过UFO
抵达这里的绿色小人儿，
抵达这里的绿色小人儿，
00:16
Not little green humanoids
arriving in shiny UFOs,
arriving in shiny UFOs,
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00:19
although that would be nice.
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当然这样很不错。
不过是关于寻找外太空
围绕恒星运行的行星。
围绕恒星运行的行星。
00:21
But it's the search for planets
orbiting stars far away.
orbiting stars far away.
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我们天空中的每一颗恒星都是太阳。
00:25
Every star in our sky is a sun.
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00:27
And if our sun has planets --
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如果说太阳有围绕它的行星——
00:29
Mercury, Venus, Earth, Mars, etc.,
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水星，金星，地球，火星，等等，
当然其他的恒星周围也应该有行星，
00:31
surely those other stars
should have planets also,
should have planets also,
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而且它们的确有。
00:34
and they do.
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在过去的20多年中，
00:35
And in the last two decades,
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天文学家已经找到了数千个系外行星。
00:36
astronomers have found
thousands of exoplanets.
thousands of exoplanets.
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00:40
Our night sky is literally
teeming with exoplanets.
teeming with exoplanets.
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我们的夜空的确遍布着系外行星。
从统计学的角度来说，我们知道
00:43
We know, statistically speaking,
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每一个恒星都拥有至少一颗行星。
00:44
that every star has at least one planet.
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00:47
And in the search for planets,
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在搜索行星的过程中，
在未来搜索像地球这样的行星，
00:49
and in the future,
planets that might be like Earth,
planets that might be like Earth,
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可以帮助我们回答
00:52
we're able to help address
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一些最不可思议又充满神秘的问题，
00:54
some of the most amazing
and mysterious questions
and mysterious questions
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这些问题已经困扰了全人类几个世纪。
00:57
that have faced humankind for centuries.
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我们为什么会存在？
00:59
Why are we here?
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01:01
Why does our universe exist?
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为什么我们的宇宙会存在？
01:03
How did Earth form and evolve?
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地球是如何形成和演化的？
01:05
How and why did life originate
and populate our planet?
and populate our planet?
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生命如何以及为什么会诞生
并在这个星球上繁衍？
并在这个星球上繁衍？
01:09
The second question
that we often think about is:
that we often think about is:
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我们经常思考的第二个问题是：
我们是唯一存在的生命吗？
01:12
Are we alone?
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01:14
Is there life out there?
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外太空中还有其他生命吗？
01:17
Who is out there?
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其他生命是什么样子呢？
01:19
You know, this question has been around
for thousands of years,
for thousands of years,
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这个问题已经存在了几千年，
至少在古希腊哲学家的时代
就已经存在了。
就已经存在了。
01:22
since at least the time
of the Greek philosophers.
of the Greek philosophers.
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但是我今天想要告诉你们，
我们已经
我们已经
01:25
But I'm here to tell you
just how close we're getting
just how close we're getting
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非常接近这个问题的答案了。
01:27
to finding out the answer
to this question.
to this question.
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这是人类历史上第一次
对这个答案触手可及。
对这个答案触手可及。
01:30
It's the first time in human history
that this really is within reach for us.
that this really is within reach for us.
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01:35
Now when I think about the possibilities
for life out there,
for life out there,
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当我想到外太空存在生命的可能性，
我就想到了我们的太阳
只是若干恒星中的一颗。
只是若干恒星中的一颗。
01:38
I think of the fact that our sun
is but one of many stars.
is but one of many stars.
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01:42
This is a photograph of a real galaxy,
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这是一个真实的星系的照片，
我们认为我们的银河系
差不多就是这一个样子。
差不多就是这一个样子。
01:44
we think our Milky Way
looks like this galaxy.
looks like this galaxy.
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其中聚集了很多
彼此紧密联系的恒星。
彼此紧密联系的恒星。
01:47
It's a collection of bound stars.
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但我们的（太阳）只是
千亿颗恒星中的一颗，
千亿颗恒星中的一颗，
01:48
But our [sun] is one
of hundreds of billions of stars
of hundreds of billions of stars
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我们的银河系也是
千亿个星系中的一个。
千亿个星系中的一个。
01:53
and our galaxy is one of upwards
of hundreds of billions of galaxies.
of hundreds of billions of galaxies.
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01:58
Knowing that small planets
are very common,
are very common,
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小行星更是不计其数，
可以做一下粗略的计算。
02:01
you can just do the math.
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02:03
And there are just so many stars
and so many planets out there,
and so many planets out there,
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宇宙中的星球真的是太多太多了，
一定还会有其他生命存在。
02:07
that surely, there must be life
somewhere out there.
somewhere out there.
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02:11
Well, the biologists get furious
with me for saying that,
with me for saying that,
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不过生物学家们极其不赞同这种说法，
因为我们毕竟还没有任何相关的证据。
02:14
because we have absolutely no evidence
for life beyond Earth yet.
for life beyond Earth yet.
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02:18
Well, if we were able to look
at our galaxy from the outside
at our galaxy from the outside
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假设能够从外太空
观测我们所在的星系，
观测我们所在的星系，
02:23
and zoom in to where our sun is,
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并聚焦到太阳，
我们就会看到一幅恒星的分布图。
02:26
we see a real map of the stars.
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02:28
And the highlighted stars
are those with known exoplanets.
are those with known exoplanets.
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那些被突出标注的恒星
都有已知的系外行星。
都有已知的系外行星。
02:31
This is really just
the tip of the iceberg.
the tip of the iceberg.
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这张图展现的仅仅是冰山一角而已。
02:34
Here, this animation is zooming in
onto our solar system.
onto our solar system.
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这个动画突出展示了我们的太阳系。
02:38
And you'll see here the planets
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你们可以看到一些行星和宇宙飞船，
02:40
as well as some spacecraft
that are also orbiting our sun.
that are also orbiting our sun.
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它们都在围绕着我们的太阳运行。
02:44
Now if we can imagine going
to the West Coast of North America,
to the West Coast of North America,
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假设我们在北美洲的西海岸
仰望夜空，
02:48
and looking out at the night sky,
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这就是我们在一个春季的夜晚
能够看到的景象。
能够看到的景象。
02:50
here's what we'd see on a spring night.
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你们可以看到星座的交替，
02:52
And you can see
the constellations overlaid
the constellations overlaid
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还有很多带有行星的恒星。
02:54
and again, so many stars with planets.
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天空里有一个区域密布着数千颗行星。
02:57
There's a special patch of the sky
where we have thousands of planets.
where we have thousands of planets.
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开普勒太空望远镜在这里聚焦了很多年。
03:01
This is where the Kepler Space Telescope
focused for many years.
focused for many years.
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03:05
Let's zoom in and look
at one of the favorite exoplanets.
at one of the favorite exoplanets.
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我们再继续放大，
看一下其中一个比较有名的系外行星。
看一下其中一个比较有名的系外行星。
03:10
This star is called Kepler-186f.
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这颗行星叫开普勒-186f。
03:14
It's a system of about five planets.
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这个系统中有大约5个行星。
这里要提一下，这其中大多数的
系外行星我们都不太了解。
系外行星我们都不太了解。
03:16
And by the way, most of these exoplanets,
we don't know too much about.
we don't know too much about.
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我们只知道它们的大小，
轨道之类的信息。
轨道之类的信息。
03:20
We know their size, and their orbit
and things like that.
and things like that.
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不过开普勒-186f非常特殊。
03:23
But there's a very special planet
here called Kepler-186f.
here called Kepler-186f.
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它处在一个距离恒星
并不太远的区域内，
并不太远的区域内，
03:27
This planet is in a zone
that is not too far from the star,
that is not too far from the star,
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这就意味着那里的温度
可能非常适宜物种生存。
可能非常适宜物种生存。
03:31
so that the temperature
may be just right for life.
may be just right for life.
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这里我们强化了艺术效果，
03:35
Here, the artist's conception
is just zooming in
is just zooming in
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想要给大家展示一下
这个行星可能的形貌。
这个行星可能的形貌。
03:38
and showing you what that planet
might be like.
might be like.
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03:43
So, many people have this
romantic notion of astronomers
romantic notion of astronomers
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或许很多人都会带着
一种浪漫的想象，
一种浪漫的想象，
觉得天文学家们都是在孤寂的山顶，
03:48
going to the telescope
on a lonely mountaintop
on a lonely mountaintop
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通过巨大的望远镜来
观察绚丽多彩的夜空的。
观察绚丽多彩的夜空的。
03:52
and looking at the spectacular night sky
through a big telescope.
through a big telescope.
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不过事实上，我们只是在计算机上操作，
跟其他人没什么两样，
跟其他人没什么两样，
03:55
But actually, we just work
on our computers like everyone else,
on our computers like everyone else,
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我们通过邮件或者数据库下载数据。
03:59
and we get our data by email
or downloading from a database.
or downloading from a database.
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所以，与其说我是来告诉大家
04:03
So instead of coming here to tell you
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数据本身和数据分析
有多么枯燥，
有多么枯燥，
04:05
about the somewhat tedious nature
of the data and data analysis
of the data and data analysis
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我们的计算机模型有多么复杂，
04:08
and the complex computer models we make,
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不如说我想以一种不同的
方式给大家展示
方式给大家展示
04:10
I have a different way
to try to explain to you
to try to explain to you
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我们对系外行星的一些看法和思考。
04:13
some of the things
that we're thinking about exoplanets.
that we're thinking about exoplanets.
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这里有一张旅行海报：
04:15
Here's a travel poster:
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"开普勒-186f：
04:16
"Kepler-186f:
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一边的草总是比另一边更红。“
04:19
Where the grass is always redder
on the other side."
on the other side."
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这是因为开普勒-186f围绕着
一颗红色的恒星运行，
一颗红色的恒星运行，
04:22
That's because Kepler-186f
orbits a red star,
orbits a red star,
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我们只是猜测那上面的植物，
04:25
and we're just speculating
that perhaps the plants there,
that perhaps the plants there,
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假设有可以进行光合作用的植物，
04:28
if there is vegetation
that does photosynthesis,
that does photosynthesis,
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那些植物就会含有不同的色素，
让它们看起来是红色。
让它们看起来是红色。
04:31
it has different pigments and looks red.
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04:34
"Enjoy the gravity on HD 40307g,
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”享受HD 40307g上面的重力吧，
这里是超级地球。“
04:38
a Super-Earth."
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这颗行星比地球的质量要大，
04:40
This planet is more massive than Earth
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拥有更大的表面重力。
04:42
and has a higher surface gravity.
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04:44
"Relax on Kepler-16b,
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”来开普勒-16b上放松一下吧，
你的影子永远不会孤单。“
04:47
where your shadow always has company."
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（笑声）
04:49
(Laughter)
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据我们所知，有数十个行星都
是围绕着两颗恒星运行，
是围绕着两颗恒星运行，
04:51
We know of a dozen planets
that orbit two stars,
that orbit two stars,
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估计还会有更多。
04:55
and there's likely many more out there.
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如果我们可以探访其中一颗行星，
04:57
If we could visit one of those planets,
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你确实可以看到两次日落，
04:59
you literally would see two sunsets
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并同时形成两个影子。
05:01
and have two shadows.
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05:03
So actually, science fiction
got some things right.
got some things right.
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事实上，科幻小说中的
一些描述是正确的。
一些描述是正确的。
比如《星球大战》中的塔图因。
05:05
Tatooine from Star Wars.
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05:08
And I have a couple of other
favorite exoplanets
favorite exoplanets
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还有一些其他的系外星球，
我也想给大家介绍一下。
05:10
to tell you about.
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这个叫做开普勒-10b，
05:11
This one is Kepler-10b,
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它的温度极高。
05:13
it's a hot, hot planet.
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05:15
It orbits over 50 times closer to its star
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它的运行轨道距离其围绕的恒星
只有地球和太阳距离的五十分之一。
05:18
than our Earth does to our sun.
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正是因为它的温度太高，
05:20
And actually, it's so hot,
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我们无法探访任何这样的行星，
即便我们试图接近它，
即便我们试图接近它，
05:22
we can't visit any
of these planets, but if we could,
of these planets, but if we could,
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在到达那里之前也早就熔化了。
05:25
we would melt long before we got there.
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我们认为它的地表温度足够熔化岩石，
05:27
We think the surface
is hot enough to melt rock
is hot enough to melt rock
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能够形成液态的岩浆湖。
05:29
and has liquid lava lakes.
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05:31
Gliese 1214b.
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格利泽1214b。
我们已经知道了
这颗行星的质量和体积，
这颗行星的质量和体积，
05:33
This planet, we know the mass and the size
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它的密度比较低。
05:35
and it has a fairly low density.
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温度也不算太高。
05:36
It's somewhat warm.
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但我们对它的了解也仅限于此，
05:38
We actually don't know
really anything about this planet,
really anything about this planet,
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不过它上面可能有水存在，
05:40
but one possibility
is that it's a water world,
is that it's a water world,
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有点像木星的一颗放大版的
遍布冰雪的卫星，
遍布冰雪的卫星，
05:43
like a scaled-up version
of one of Jupiter's icy moons
of one of Jupiter's icy moons
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其水含量可能占据了质量的50%。
05:46
that might be 50 percent water by mass.
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在这种情况下，它就有可能覆盖了
一层很厚的蒸汽大气层，
一层很厚的蒸汽大气层，
05:49
And in this case, it would have
a thick steam atmosphere
a thick steam atmosphere
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就在海洋的上空，
05:52
overlaying an ocean,
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不过海里不是液态水，
05:54
not of liquid water,
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而是一种奇特状态的水，
一种超流体——
一种超流体——
05:55
but of an exotic form
of water, a superfluid --
of water, a superfluid --
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不算是气体，也不算是液体。
05:58
not quite a gas, not quite a liquid.
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其下遍布的也不是岩石，
06:00
And under that wouldn't be rock,
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而是一种高压状态的冰，
06:02
but a form of high-pressure ice,
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类似于冰IX（冰九，拥有某种晶体结构的冰。
——译注）。
——译注）。
06:04
like ice IX.
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06:06
So out of all these planets out there,
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除了这些多样性已经让我们感到
惊讶的行星以外，
06:08
and the variety
is just simply astonishing,
is just simply astonishing,
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我们最想找到的是我们称作
”古迪洛克行星“的星球。
”古迪洛克行星“的星球。
06:12
we mostly want to find the planets
that are Goldilocks planets, we call them.
that are Goldilocks planets, we call them.
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体积不大不小，
06:17
Not too big, not too small,
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温度不高不低——
06:19
not too hot, not too cold --
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刚刚好适宜物种生存。
06:20
but just right for life.
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06:22
But to do that,
we'd have to be able to look
we'd have to be able to look
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不过要做到这一点，
我们需要能够检测到
我们需要能够检测到
这个行星的大气层，
06:24
at the planet's atmosphere,
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因为大气层就像一块保温毯——
06:26
because the atmosphere
acts like a blanket trapping heat --
acts like a blanket trapping heat --
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具有温室效应。
06:28
the greenhouse effect.
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我们需要监测到其他行星上的
06:30
We have to be able to assess
the greenhouse gases
the greenhouse gases
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温室气体。
06:33
on other planets.
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06:35
Well, science fiction
got some things wrong.
got some things wrong.
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从这一点来说，
科幻小说就显得不那么真实了。
科幻小说就显得不那么真实了。
《进取号》
（剧情设定在《星际旅行》的宇宙中）
（剧情设定在《星际旅行》的宇宙中）
06:37
The Star Trek Enterprise
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需要以极高速度旅行很长的距离
06:39
had to travel vast distances
at incredible speeds
at incredible speeds
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到达其它行星并环绕飞行，
06:42
to orbit other planets
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这样史波克大副才能
分析大气层的成分，
分析大气层的成分，
06:44
so that First Officer Spock
could analyze the atmosphere
could analyze the atmosphere
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从而判断该行星是否适宜居住，
06:48
to see if the planet was habitable
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或者那上面是否有生命存活。
06:50
or if there were lifeforms there.
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06:52
Well, we don't need
to travel at warp speeds
to travel at warp speeds
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不过我们并不需要以极限高速行驶
来获取其他行星上的大气数据，
06:55
to see other planet atmospheres,
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当然我并不想打击那些跃跃欲试
想要实现这项工作的
想要实现这项工作的
06:57
although I don't want to dissuade
any budding engineers
any budding engineers
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工程师们的积极性。
07:00
from figuring out how to do that.
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我们其实可以直接在地球的轨道范围内
07:02
We actually can and do study
planet atmospheres
planet atmospheres
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研究那些大气层。
07:04
from here, from Earth orbit.
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这是一张由亚特兰蒂斯航天飞机拍摄的
07:06
This is a picture, a photograph
of the Hubble Space Telescope
of the Hubble Space Telescope
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哈勃太空望远镜的照片，
07:09
taken by the shuttle Atlantis
as it was departing
as it was departing
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这架航天飞机出发时，最后一次
前往哈勃的载人太空飞行已经完成。
前往哈勃的载人太空飞行已经完成。
07:12
after the last
human space flight to Hubble.
human space flight to Hubble.
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他们在飞机上安装了一个新的照相机，
07:14
They installed a new camera, actually,
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可以采集系外行星的大气数据。
07:16
that we use for exoplanet atmospheres.
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目前，我们已经能够研究
数十个系外行星的大气层，
数十个系外行星的大气层，
07:18
And so far, we've been able to study
dozens of exoplanet atmospheres,
dozens of exoplanet atmospheres,
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其中有6个我们可以得到
非常详细的数据。
非常详细的数据。
07:23
about six of them in great detail.
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不过那些都不是像地球这样的小行星。
07:25
But those are not
small planets like Earth.
small planets like Earth.
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它们非常庞大，温度很高，
很容易观测到。
很容易观测到。
07:27
They're big, hot planets
that are easy to see.
that are easy to see.
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我们还没准备好，
07:30
We're not ready,
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还不具备研究小型系外星球的技术。
07:31
we don't have the right technology yet
to study small exoplanets.
to study small exoplanets.
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07:36
But nevertheless,
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不过尽管如此，
我还是想跟大家解释一下我们是
如何研究系外行星大气的。
如何研究系外行星大气的。
07:37
I wanted to try to explain to you
how we study exoplanet atmospheres.
how we study exoplanet atmospheres.
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07:41
I want you to imagine,
for a moment, a rainbow.
for a moment, a rainbow.
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大家可以想象一下彩虹。
07:44
And if we could look
at this rainbow closely,
at this rainbow closely,
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如果我们可以近距离观察彩虹，
就能发现一些暗色的线缺失了。
07:47
we would see that some
dark lines are missing.
dark lines are missing.
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07:51
And here's our sun,
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这是我们的太阳，
白色的光被分解了，
07:52
the white light of our sun split up,
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不是被雨滴，而是被光谱仪分解了。
07:54
not by raindrops, but by a spectrograph.
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我们可以看到所有这些
暗色的竖线。
暗色的竖线。
07:56
And you can see
all these dark, vertical lines.
all these dark, vertical lines.
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有的很窄，有的很宽，
07:59
Some are very narrow, some are wide,
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有的边缘很模糊。
08:00
some are shaded at the edges.
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这实际上就是过去的一个多世纪以来，
08:02
And this is actually how astronomers
have studied objects in the heavens,
have studied objects in the heavens,
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宇航员们研究太空物质的方式。
08:06
literally, for over a century.
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在这张图中，每种原子和分子
08:07
So here, each different atom and molecule
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都有一组特殊的谱线，
08:10
has a special set of lines,
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你们可以把它当做一种指纹信息。
08:11
a fingerprint, if you will.
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我们就是利用这些信息
研究系外行星的大气成分的。
研究系外行星的大气成分的。
08:13
And that's how we study
exoplanet atmospheres.
exoplanet atmospheres.
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我永远也忘不了在20年前
08:15
And I'll just never forget
when I started working
when I started working
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刚刚开始研究系外行星大气的时候，
08:18
on exoplanet atmospheres 20 years ago,
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多少人告诉我，
08:20
how many people told me,
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”这根本行不通。
08:21
"This will never happen.
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我们永远也不可能做到。
干嘛白费功夫呢？“
干嘛白费功夫呢？“
08:22
We'll never be able to study them.
Why are you bothering?"
Why are you bothering?"
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这也是为什么我很高兴的告诉你们
目前所有的关于大气的研究，
目前所有的关于大气的研究，
08:25
And that's why I'm pleased to tell you
about all the atmospheres studied now,
about all the atmospheres studied now,
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已经完全自成体系了。
08:29
and this is really a field of its own.
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1849
那么对于那些在将来我们可以观测到的
08:31
So when it comes to
other planets, other Earths,
other planets, other Earths,
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2522
其他行星，那些类地行星，
08:33
in the future when we can observe them,
189
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我们需要寻找哪些气体呢？
08:35
what kind of gases
would we be looking for?
would we be looking for?
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2059
08:38
Well, you know, our own Earth
has oxygen in the atmosphere
has oxygen in the atmosphere
191
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大家都知道，我们地球上的大气
含有20%体积的氧气。
08:41
to 20 percent by volume.
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08:43
That's a lot of oxygen.
193
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这个含量是很高的。
08:45
But without plants
and photosynthetic life,
and photosynthetic life,
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不过没有植物和其它光合生物，
大气中就不会有氧气，
08:48
there would be no oxygen,
195
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1410
事实上连一丁点儿都不会有。
08:49
virtually no oxygen in our atmosphere.
196
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1841
08:52
So oxygen is here because of life.
197
520116
1923
所以氧气的出现是因为生命的存在。
所以我们的目标就是要
找到其他行星的大气中
找到其他行星的大气中
08:54
And our goal then is to look for gases
in other planet atmospheres,
in other planet atmospheres,
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原本并不应该存在的气体，
08:58
gases that don't belong,
199
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2037
或许可以归功于生命的存在。
09:00
that we might be able
to attribute to life.
to attribute to life.
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2383
那么哪些分子是我们需要寻找的呢？
09:02
But which molecules should we search for?
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我已经告诉过你们系外行星的
种类有多么繁杂了。
种类有多么繁杂了。
09:04
I actually told you
how diverse exoplanets are.
how diverse exoplanets are.
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在我们寻找类地行星的过程中，
09:07
We expect that to continue in the future
203
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1997
一定还会有更多种类的外行星出现。
09:09
when we find other Earths.
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537475
1301
这就是我目前正在从事的主要工作之一，
09:10
And that's one of the main things
I'm working on now,
I'm working on now,
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对此我有一番自己的理论。
09:13
I have a theory about this.
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1293
这倒是提醒我了，几乎每天
09:14
It reminds me that nearly every day,
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2288
我都会收到一封或者很多封电子邮件，
09:17
I receive an email or emails
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545025
2652
发件人都对重力或者宇宙物理学
09:19
from someone with a crazy theory
about physics of gravity
about physics of gravity
209
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3627
提出了自己疯狂的理论。
09:23
or cosmology or some such.
210
551352
1832
不过，在此还是想提醒大家，
请不要再给我发这种邮件了。
请不要再给我发这种邮件了。
09:25
So, please don't email me
one of your crazy theories.
one of your crazy theories.
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3333
（笑声）
09:28
(Laughter)
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1214
我有一套自己的疯狂理论。
09:29
Well, I had my own crazy theory.
213
557803
2178
那么麻省理工的教授要跟谁探讨呢？
09:32
But, who does the MIT professor go to?
214
560005
1984
09:34
Well, I emailed a Nobel Laureate
in Physiology or Medicine
in Physiology or Medicine
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562703
4211
我曾经给一名诺贝尔生理学或医学的
获奖者发过邮件，
获奖者发过邮件，
他说，”听上去还不错，
过来我们讨论一下吧。“
过来我们讨论一下吧。“
09:38
and he said, "Sure, come and talk to me."
216
566938
1973
于是我就带上了两个
生物化学领域的朋友，
生物化学领域的朋友，
09:40
So I brought my two biochemistry friends
217
568935
1999
跟他介绍了一下我们的疯狂理论。
09:42
and we went to talk to him
about our crazy theory.
about our crazy theory.
218
570958
2352
那个理论就是，
生命制造了所有的小分子，
生命制造了所有的小分子，
09:45
And that theory was that life
produces all small molecules,
produces all small molecules,
219
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3441
不计其数的小分子。
09:48
so many molecules.
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576799
1674
几乎是作为一个非化学领域专家，
我能想到的所有分子。
我能想到的所有分子。
09:50
Like, everything I could think of,
but not being a chemist.
but not being a chemist.
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2895
比方说：
09:53
Think about it:
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1183
二氧化碳，一氧化碳，
09:54
carbon dioxide, carbon monoxide,
223
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2030
氢分子，氮分子，
09:56
molecular hydrogen, molecular nitrogen,
224
584677
1859
甲烷，氯甲烷——
09:58
methane, methyl chloride --
225
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1366
太多太多了。
09:59
so many gases.
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1161
它们之所以存在也有很多其他的原因，
10:01
They also exist for other reasons,
227
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1935
不过单单是生命，甚至就可以产生臭氧。
10:03
but just life even produces ozone.
228
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1852
于是我们去跟他讨论了这套观点，
10:04
So we go to talk to him about this,
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1758
结果很快就被他否决了。
10:06
and immediately, he shot down the theory.
230
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2142
10:09
He found an example that didn't exist.
231
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2267
他找到了一个并不存在的气体的例子。
10:11
So, we went back to the drawing board
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1781
于是我们只好回去继续推导，
10:13
and we think we have found something
very interesting in another field.
very interesting in another field.
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我们认为我们已经找到了一些
在其他领域中很有意思的东西。
在其他领域中很有意思的东西。
回到系外行星这个话题，
10:17
But back to exoplanets,
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重点是生命制造了这么多种气体，
10:18
the point is that life produces
so many different types of gases,
so many different types of gases,
235
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3279
差不多几千种。
10:21
literally thousands of gases.
236
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2212
我们现在的任务就是试图找出
10:24
And so what we're doing now
is just trying to figure out
is just trying to figure out
237
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哪些种类的系外行星上的哪些气体
10:26
on which types of exoplanets,
238
614879
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可能是由生命制造出来的。
10:28
which gases could be attributed to life.
239
616492
3220
10:34
And so when it comes time
when we find gases
when we find gases
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2048
所以当我们在系外行星的大气中
找到了那些气体，
10:36
in exoplanet atmospheres
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1351
我们很难确定这些气体是怎么来的，
10:37
that we won't know
if they're being produced
if they're being produced
242
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2096
是由外星人制造的，
还是来自树木，
还是来自树木，
10:39
by intelligent aliens or by trees,
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3030
或者沼泽地，
10:42
or a swamp,
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或者仅仅是来源于简单的
单细胞生物。
单细胞生物。
10:44
or even just by simple,
single-celled microbial life.
single-celled microbial life.
245
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2861
10:47
So working on the models
246
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1550
所以建立一些模型，
应用一些生物化学的知识，
10:49
and thinking about biochemistry,
247
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1651
我们就会得到我们想要的答案。
10:50
it's all well and good.
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1197
那么在实际过程中面临的
最大挑战就是：要怎么做？
最大挑战就是：要怎么做？
10:52
But a really big challenge
ahead of us is: how?
ahead of us is: how?
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2885
要怎么找到这些行星？
10:54
How are we going to find these planets?
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2162
其实可以通过很多方式来寻找，
10:57
There are actually many ways
to find planets,
to find planets,
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2204
10:59
several different ways.
252
647310
1519
各种不同的方式。
不过我重点在研究的是
要如何实现这样一个途径，
要如何实现这样一个途径，
11:00
But the one that I'm most focused on
is how can we open a gateway
is how can we open a gateway
253
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3859
在未来
11:04
so that in the future,
254
652736
1237
可以让我们找到数百个类地行星。
11:05
we can find hundreds of Earths.
255
653997
1849
我们事实上已经开始行动了。
11:07
We have a real shot
at finding signs of life.
at finding signs of life.
256
655870
2333
我刚刚完成了一个
由我负责的两年项目，
由我负责的两年项目，
11:10
And actually, I just finished
leading a two-year project
leading a two-year project
257
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3126
在这个特殊的项目中，
11:13
in this very special phase
258
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2088
我们提出了”遮星板“的概念。
11:15
of a concept we call the starshade.
259
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2654
遮星板是一个形状非常特殊的屏障，
11:18
And the starshade
is a very specially shaped screen
is a very specially shaped screen
260
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2953
我们想要将它送入太空，
11:21
and the goal is to fly that starshade
261
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1867
遮挡恒星的光线，
11:23
so it blocks out the light of a star
262
671035
3094
这样就可以通过望远镜
直接观测那些行星了。
直接观测那些行星了。
11:26
so that the telescope
can see the planets directly.
can see the planets directly.
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这张图上你们可以看到
我和两名项目成员，
我和两名项目成员，
11:29
Here, you can see myself
and two team members
and two team members
264
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2393
正在展示遮星板的一块很小的局部。
11:31
holding up one small part
of the starshade.
of the starshade.
265
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2189
它的形状就像一个巨大的花朵，
11:33
It's shaped like a giant flower,
266
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1580
这是一片花瓣的雏形。
11:35
and this is one of the prototype petals.
267
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2483
11:38
The concept is that a starshade
and telescope could launch together,
and telescope could launch together,
268
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4461
这个过程就是把遮星板和
望远镜一同送入太空，
望远镜一同送入太空，
遮星板的花瓣会从运载器上打开。
11:43
with the petals unfurling
from the stowed position.
from the stowed position.
269
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2594
11:46
The central truss would expand,
270
694896
2056
中心的桁架会展开，
花瓣也会迅速延展到位。
11:48
with the petals snapping into place.
271
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3092
这个过程需要做到非常精准，
11:52
Now, this has to be made very precisely,
272
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2230
也就是说花瓣的精度要达到微米级，
11:54
literally, the petals to microns
273
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1588
定位的精准度要达到毫米级。
11:55
and they have to deploy to millimeters.
274
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2715
这一整个部件需要移动至
11:58
And this whole structure would have to fly
275
706697
2055
距离望远镜数万公里的距离。
12:00
tens of thousands of kilometers
away from the telescope.
away from the telescope.
276
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3359
它的直径大概有几十米。
12:04
It's about tens of meters in diameter.
277
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2142
12:06
And the goal is to block out
the starlight to incredible precision
the starlight to incredible precision
278
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4953
它能够以难以置信的精度
实现对恒星光线的遮挡，
实现对恒星光线的遮挡，
这样我们就能直接观测行星了。
12:11
so that we'd be able to see
the planets directly.
the planets directly.
279
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2738
12:15
And it has to be a very special shape,
280
723333
2229
它的形状必须十分特殊，
这是由物理学中的衍射现象决定的。
12:17
because of the physics of defraction.
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这是我们从事的一项实际的项目，
12:19
Now this is a real project
that we worked on,
that we worked on,
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说真的，你们想象不出这有多难。
12:21
literally, you would not believe how hard.
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为了证明这并不只是一种假想，
12:24
Just so you believe
it's not just in movie format,
it's not just in movie format,
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给你们展示一个真实的照片，
12:26
here's a real photograph
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这是实验室中的第二代
遮星板调试试验台。
遮星板调试试验台。
12:28
of a second-generation
starshade deployment test bed in the lab.
starshade deployment test bed in the lab.
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在这个项目中，我只是想让你们知道
12:33
And in this case,
I just wanted you to know
I just wanted you to know
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中心桁架装有
12:35
that that central truss
has heritage left over
has heritage left over
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太空大范围无线电部署的一部分。
12:38
from large radio deployables in space.
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12:41
So after all of that hard work
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那么，在这一系列我们试图寻找
那些外行星中的神秘气体，
12:43
where we try to think of all the crazy
gases that might be out there,
gases that might be out there,
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以及建造了极其复杂的太空望远镜
12:46
and we build the very
complicated space telescopes
complicated space telescopes
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之类的艰难任务之后，
12:49
that might be out there,
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我们会有什么收获呢？
12:51
what are we going to find?
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12:52
Well, in the best case,
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最好的情况是，
我们会获得另一个类地行星的图像。
12:54
we will find an image
of another exo-Earth.
of another exo-Earth.
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12:58
Here is Earth as a pale blue dot.
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这张图上的地球是一个淡蓝色的小点。
这是一张地球的真实照片，
13:00
And this is actually
a real photograph of Earth
a real photograph of Earth
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由旅行者1号航天飞机
13:03
taken by the Voyager 1 spacecraft,
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从40亿英里外的距离拍摄的。
13:05
four billion miles away.
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13:07
And that red light is just scattered light
in the camera optics.
in the camera optics.
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那条红色的光线只是相机的
光学部件散射出的光。
光学部件散射出的光。
13:11
But what's so awesome to consider
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想象一下，
如果存在着高智慧的外星生物，
如果存在着高智慧的外星生物，
正绕着我们附近恒星的行星运转，
13:13
is that if there are intelligent aliens
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它们搭建出了我们正在建造的
13:16
orbiting on a planet
around a star near to us
around a star near to us
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复杂的太空望远镜，
13:20
and they build complicated
space telescopes
space telescopes
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2045
它们能看到的也仅仅是
一个淡蓝色的小点，
一个淡蓝色的小点，
13:22
of the kind that we're trying to build,
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1927
极其微小的光点，
13:24
all they'll see is this pale blue dot,
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这该有多酷啊！
13:27
a pinprick of light.
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13:29
And so sometimes, when I pause to think
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有时候，当我停下来思考
我所面临的难题和我远大的理想，
13:32
about my professional struggle
and huge ambition,
and huge ambition,
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这跟浩瀚的宇宙相比
13:36
it's hard to think about that
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1993
真的不算什么。
13:38
in contrast to the vastness
of the universe.
of the universe.
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13:42
But nonetheless, I am devoting
the rest of my life
the rest of my life
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不过尽管如此，
我还是打算奉献我的一生
我还是打算奉献我的一生
来寻找另一个地球。
13:46
to finding another Earth.
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13:48
And I can guarantee
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而且我可以保证，
用下一代的太空望远镜，
13:50
that in the next generation
of space telescopes,
of space telescopes,
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2383
也就是第二代，
13:52
in the second generation,
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1540
我们将会有能力找到并
识别出其他的类地行星。
识别出其他的类地行星。
13:54
we will have the capability
to find and identity other Earths.
to find and identity other Earths.
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我们也将能够分解恒星发出的光线，
13:59
And the capability
to split up the starlight
to split up the starlight
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2674
能够找到那些气体，
14:02
so that we can look for gases
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1553
获得那些大气中的温室气体成分信息，
14:04
and assess the greenhouse gases
in the atmosphere,
in the atmosphere,
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3486
估算星球表面的温度，
14:07
estimate the surface temperature,
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1598
并寻找生命的迹象。
14:09
and look for signs of life.
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1758
14:11
But there's more.
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1421
不过我们还有更长远的打算。
在寻找其他类地行星的同时，
14:13
In this case of searching
for other planets like Earth,
for other planets like Earth,
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3364
我们还在制作一幅展示
14:16
we are making a new kind of map
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2595
附近恒星及其行星的新太空地图，
14:19
of the nearby stars
and of the planets orbiting them,
and of the planets orbiting them,
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包括有可能适宜人类居住的（行星）。
14:22
including [planets] that actually might be
inhabitable by humans.
inhabitable by humans.
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3771
14:26
And so I envision that our descendants,
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2381
我能够想像我们的后代，
在几百年之后，
14:29
hundreds of years from now,
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1805
能够通过星际旅行到达其他的星球。
14:31
will embark on an interstellar
journey to other worlds.
journey to other worlds.
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3027
14:35
And they will look back at all of us
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2912
他们能够回首我们这一代，
第一个发现类地新世界的一代。
14:37
as the generation who first found
the Earth-like worlds.
the Earth-like worlds.
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3008
14:41
Thank you.
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谢谢大家。
（掌声）
14:42
(Applause)
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June Cohen （JC）:
你先来提问吧 ，
你先来提问吧 ，
14:49
June Cohen: And I give you,
for a question,
for a question,
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有请罗塞塔任务的负责人，
Fred Jansen。
Fred Jansen。
14:51
Rosetta Mission Manager Fred Jansen.
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1728
14:53
Fred Jansen: You mentioned halfway through
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2031
Fred Jansen：
你部分提到了
你部分提到了
可以分析类地行星光谱的技术
14:55
that the technology
to actually look at the spectrum
to actually look at the spectrum
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3787
还尚未实现。
14:59
of an exoplanet like Earth
is not there yet.
is not there yet.
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2629
你认为什么时候可以实现，
15:02
When do you expect this will be there,
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1887
要如何实现呢？
15:04
and what's needed?
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莎拉·西格尔（SS）：事实上
我们打算依靠下一代的哈勃望远镜。
我们打算依靠下一代的哈勃望远镜。
15:05
Actually, what we expect is what we call
our next-generation Hubble telescope.
our next-generation Hubble telescope.
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4615
15:10
And this is called the James Webb
Space Telescope,
Space Telescope,
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2341
我们叫它詹姆斯韦伯太空望远镜，
会在2018年把它送上太空，
15:12
and that will launch in 2018,
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1703
整个计划大概是这样的，
15:14
and that's what we're going to do,
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1822
我们会观测一种特殊的行星，
15:16
we're going to look
at a special kind of planet
at a special kind of planet
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叫做过渡系外行星，
15:18
called transient exoplanets,
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1456
那将是我们研究小行星上可能预示着
15:20
and that will be our first shot
at studying small planets
at studying small planets
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生命迹象的气体的第一次尝试。
15:23
for gases that might indicate
the planet is habitable.
the planet is habitable.
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3298
15:27
JC: I'm going to ask you
one follow-up question, too, Sara,
one follow-up question, too, Sara,
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2809
JC：莎拉，我还有个大众一点的
问题要问一下你。
15:30
as the generalist.
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我真的对你的职业生涯中所面临的
15:31
So I am really struck
by the notion in your career
by the notion in your career
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反对声音感到很震惊，
15:34
of the opposition you faced,
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922657
1399
也就是当你开始思考系外行星，
15:36
that when you began thinking
about exoplanets,
about exoplanets,
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2144
科学领域对它们是否存在持有
15:38
there was extreme skepticism
in the scientific community
in the scientific community
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2666
极端怀疑的态度，
15:40
that they existed,
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1151
你证明了他们是错的。
15:42
and you proved them wrong.
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你是如何承受这些的呢？
15:43
What did it take to take that on?
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SS: 作为科学家，
15:45
SS: Well, the thing is that as scientists,
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2070
我们理应持怀疑态度，
15:47
we're supposed to be skeptical,
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1958
因为我们的工作就是
要确认其他人的观点
要确认其他人的观点
15:49
because our job to make sure
that what the other person is saying
that what the other person is saying
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是否是合理的。
15:52
actually makes sense or not.
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但是作为一名科学家，
15:53
But being a scientist,
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我觉得你们可能已经在这段演讲中看到，
15:56
I think you've seen it from this session,
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我的职责更像是探索者。
15:58
it's like being an explorer.
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1682
这需要极大的好奇心，
16:00
You have this immense curiosity,
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1989
固执，
16:02
this stubbornness,
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还需要坚定不移的意志，
16:03
this sort of resolute will
that you will go forward
that you will go forward
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2382
无论其他人说什么，都不能动摇。
16:06
no matter what other people say.
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JC：说的太好了。
非常感谢你，莎拉。
非常感谢你，莎拉。
16:08
JC: I love that. Thank you, Sara.
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（掌声）
16:09
(Applause)
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Reviewed by fengshuang gao
ABOUT THE SPEAKER
Sara Seager - Exoplanet expertSara Seager’s research led to the first discovery of an atmosphere on a planet outside our solar system. Now she’s on the hunt for a twin Earth.
Why you should listen
Having helped pave the way for the current torrent of discoveries of planets outside of our solar system (or exoplanets), 2013 MacArthur Fellow Sara Seager is now preparing to fulfill her life dream of discovering a planet with nearly identical conditions to our own.
Seager’s present research and discovery mission projects include Earth-orbiting nanosatellite telescopes as well as the Starshade, a sunflower-shaped giant screen to block intrusive starlight, allowing a space telescope to zoom in on the small exoplanets that have thus far eluded our sight.
More profile about the speakerSeager’s present research and discovery mission projects include Earth-orbiting nanosatellite telescopes as well as the Starshade, a sunflower-shaped giant screen to block intrusive starlight, allowing a space telescope to zoom in on the small exoplanets that have thus far eluded our sight.
Sara Seager | Speaker | TED.com