So I'm pretty sure that I'm not the only one in this room who at some point have found myself,
我确信我不是这个房间里唯一一个这样做过的人：
you know, looking up towards the stars, and wondered, you know, "Are we it, or are there other living planets out there such as our own?"
你是否曾在某个时刻，望着天上的星星，思索着：“我们是唯一的吗？宇宙中还有像地球一样的有生命存活的星球吗？”
I guess it is possible that I'm then the only person who has obsessed enough about that question to make it my career.
但我可能是唯一一个对这个问题痴迷到把解开它当作毕生事业的人。
But moving on. How do we get to this question?
那么言归正传。我们为什么会思考这个问题呢？
Well, I would argue the first thing to do is to turn our eyes back down from the sky to our own planet, the Earth.
我建议，咱们先把目光从天空中收回，回到我们赖以生存的地球上。
And think about just how lucky did the Earth have to be to be the living planet it is.
然后想一想，地球成为这样一个有生命力的行星，是多么幸运的一件事儿。
Well, it had to be at least somewhat lucky.
多少得靠点运气吧。
Had we been sitting closer to the Sun or a bit further away, any water that we have had would have boiled off or frozen over.
如果我们距离太阳再近点儿，或者再远点儿，那地球上所有的水要么因过热而蒸发，要么因寒冷被冻住。
And I mean, it's not a given that a planet has water on it.
不是所有的行星都有水存在。
So had we been a dry planet, there would not have been a lot of life on it.
如果地球是干的，那么它将无法孕育生命。
And even if we had had all the water that we have today,
即使地球上存在我们今天所拥有的水资源，
if that water had not been accompanied by the right kind of chemicals to get life going, we would have a wet planet, but just as dead.
但如果没有适合生命生存的化学物质，那地球也只会是一个死气沉沉的大水球。
So it's so many things that can go wrong, what are the chances that they go right?
可能导致失败的因素这么多，那么成功的几率有多大呢？
What are the chances that the planet forms with at least the basic ingredients needed to have an origins of life happening?
在一颗行星上，存在着有助于生命起源的基本元素的概率到底有多大呢？
Well, let's explore that together. So if you're going to have a living planet, the first thing you're going to need is a planet.
那么，我们一起来看一看。一颗可孕育生命的行星，至少应该是一颗行星。
But not any planet will do. You're probably going to need a rather specific and earthlike planet.
但并不是随便一颗行星就可以了。至少应该是一颗类地行星。
A planet that is rocky, so you can have both oceans and land,
有着岩石表面，拥有海洋和陆地两种地表形态。
and it's sitting neither too close nor too far away from its star, but at the just-right temperature.
与恒星的距离不太远也不太近，要在温度适宜的距离内。
And it's just right for liquid water, that is.
也就是说，水以液态形式存在。
So how many of these planets do we have in our galaxy?
在银河系中，这样的行星有多少呢？
Well, one of the great discoveries of the past decades is that planets are incredibly common.
过去几十年间，我们取得的重大发现之一就是，行星是再常见不过的了。
Almost every star has a planet around them. Some have many.
几乎所有的恒星都有一颗围绕其转动的行星。有的拥有许多颗。
And among these planets, on the order of a few percent are earthlike enough that we would consider them potentially living planets.
在这些行星中，约百分之几可被视为类地行星，我们认为它们是可能孕育生命的行星。
So having the right kind of planet is actually not that difficult when we consider that there's about 100 billion stars in our galaxy.
因此，合适的行星并不难寻，考虑到整个银河系大约有一千亿颗恒星。
So that gives you about a billion potential living planets.
那么潜在的宜居行星大约有十亿颗。
But it's not enough to just be at the right temperature or have the right overall composition. You also need the right chemicals.
但是适宜的气温或环境组成还不够，还需要合适的化学物质。
And what the second and important ingredient to make a living planet is -- I think it's pretty intuitive -- it's water.
可孕育生命的行星所需的第二重要的物质，我们不难猜想--那就是水。
After all, we did define our planet as being potentially living if it had the right temperature to keep water liquid.
毕竟，温度之所以能定义环境是否可生存，是因为它能决定水是否以液态形式存在。
And I mean, here on Earth, life is water-based. But more generally, water is just really good as a meeting place for chemicals.
在地球上，水是生命结构的基本构成。更广泛地讲，水是一种非常优良的化学反应介质。
It is a very special liquid. So this is our second basic ingredient.
它是一种很特别的液体。所以水是第二个基本要素。
Now the third ingredient, I think, is probably a little bit more surprising.
现在来谈第三个要素，它可能会让你们有点吃惊。
I mean, we are going to need some organics in there, since we are thinking about organic life.
我们现在需要一些有机物，因为我们想要有机生命体。
But the organic molecule that seems to be at the center of the chemical networks that can produce biomolecules is hydrogen cyanide.
这种能组成化学物质，并进一步组成生物分子的核心有机分子就是氰化氢。
So for those of you who know what this molecule is like, you know it's something that it's a good idea to stay away from.
如果你了解这种物质，你就知道，我们应该尽量离它远点儿。
But it turns out that what's really, really bad for advanced life forms, such as yourselves,
但事实证明，对高等生物体，比如人类非常有害的物质，
is really, really good to get the chemistry started, the right kind of chemistry that can lead to origins of life.
可能对化学反应的发生十分有利，而适当的化学反应将带来生命的起源。
So now we have our three ingredients that we need, you know, the temperate planet, water and hydrogen cyanide.
那么现在，三种要素都有了，适宜的行星、液态水，以及氰化氢。
So how often do these three come together?
那么，三者同时出现的概率有多大呢？
How many temperate planets are there out there that have water and hydrogen cyanide?
在所有适宜的行星中，同时存在着液态水和氰化氢的又有多少呢？
Well, in an ideal world, we would now turn one of our telescopes towards one of these temperate planets and check for ourselves.
理想状态下，我们打开望远镜，对着这些行星，看一下就好了。
Just, "Do these planets have water and cyanides on them?" Unfortunately, we don't yet have large enough telescopes to do this.
无非就是确认“行星上有没有液态水和氰化物？”不幸的是，我们还没有具备理想观测能力的望远镜。
We can detect molecules in the atmospheres of some planets.
我们能对一部分行星的大气层分子进行探测。
But these are large planets sitting often pretty close to their star,
但仅限于大型的且与其所环绕的恒星距离很近的行星，
nothing like these, you know, just-right planets that we're talking about here, which are much smaller and further away.
并不是我们所说的那些刚好符合条件的行星，它们更小也更远。
So we have to come up with another way.
因此我们必须另想一个办法。
And the other way that we have conceived of and then followed is to instead of looking for these molecules in the planets when they exist,
我们想到并实施的另一个办法是，与其从现存的行星里寻找这些物质分子，
is to look for them in the material that's forming new planets.
不如着眼于正在合成新行星的物质。
So planets form in discs of dust and gas around young stars.
行星由年轻恒星周围的气体尘埃盘构成。
And these discs get their material from the interstellar medium.
这些盘状物由星际介质组成。
Turns out that the empty space you see between stars when you are looking up towards them, asking existential questions,
事实上，当你凝望天空，思索存在主义问题时所目睹的恒星之间的空隙，
is not as empty as it seems, but actually full of gas and dust, which can, you know, come together in clouds,
并非像看起来的那么空空荡荡，那里面充满了气体和尘埃，汇合在一起形成了星云，
then collapses to form these discs, stars and planets.
星云坍缩后形成了气体尘埃盘、恒星和行星。
And one of the things we always see when we do look at these clouds is water.
当观察星云时，你总能发现一种物质，那就是水。
You know, I think we have a tendency to think about water as something that's, you know, special to us.
我想，人们总是倾向于将水视为一种特别的存在。
Water is one of the most abundant molecules in the universe, including in these clouds, these star- and planet-forming clouds.
水是宇宙中含量最高的物质之一，在这些星云中也不例外。这些形成恒星与行星的星云。
And not only that -- water is also a pretty robust molecule: it's actually not that easy to destroy.
不仅如此--水还是一种非常稳定的分子：它不易被破坏。
So a lot of this water that is in interstellar medium will survive the rather dangerous, collapsed journey from clouds to disc, to planet.
因此，星际介质中包含的水分子，在危险的星云坍缩过程中被保存了下来，进入气体尘埃盘，最后成为行星的一部分。
So water is alright. That second ingredient is not going to be a problem.
所以，水是存在的。搜寻这第二种元素并不难。
Most planets are going to form with some access to water.
大多数行星的形成多多少少会有水的参与。
So what about hydrogen cyanide? Well, we also see cyanides and other similar organic molecules in these interstellar clouds.
那么，有没有氰化氢呢？首先，我们在这些星际介质中也观测到了氰化物和其他相似的有机分子。
But here, we're less certain about the molecules surviving, going from the cloud to the disc.
但是，从星云过渡到气体尘埃盘时，多少分子能存活下来，我们不太有信心。
They're just a bit more delicate, a bit more fragile.
它们相对比较精巧，比较脆弱。
So if we're going to know that this hydrogen cyanide is sitting in the vicinity of new planets forming,
所以，如果我们想确定氰化氢存在于正在形成的行星附近，
we'd really need to see it in the disc itself, in these planet-forming discs.
我们就必须从正在形成这颗行星的气体尘埃盘中找到它。
So about a decade ago, I started a program to look for this hydrogen cyanide and other molecules in these planet-forming discs.
大约十年前，我成立了一个项目，从形成某颗行星的气体尘埃盘中寻找氰化氢和其他分子物质。

And this is what we found. So good news, in these six images,
我们找到了这些。好消息是，在这六张图片中，
those bright pixels represent emissions originating from hydrogen cyanide in planet-forming discs hundreds of light-years away
那些较亮的像素点代表在几百光年之外，行星气体尘埃盘中氰化氢的释放，
that have made it to our telescope, onto the detector, allowing us to see it like this.
它们进入了望远镜观测范围内，被探测器捕捉到，于是被我们所看见了。
So the very good news is that these discs do indeed have hydrogen cyanide in them. That last, more elusive ingredient.
那么，好消息是我们能确定这些气体尘埃盘中确实存在着氰化氢，这最后一种难以捉摸的物质。
Now the bad news is that we don't know where in the disc it is.
坏消息是，我们无法探测出气体尘埃盘中氰化氢的具体方位。
If we look at these, I mean, no one can say they are beautiful images, even at the time when we got them.
我们来看看这几幅图，没人觉得它们很美吧，我们收到时也不觉得。
You see the pixel size is pretty big and it's actually bigger than these discs themselves.
看得出来这些像素点挺大的，实际上比它们所在的气体尘埃盘还大。
So each pixel here represents something that's much bigger than our solar system.
这里的每一个像素点都代表着一个远远大于太阳系的空间。
And that means that we don't know where in the disc the hydrogen cyanide is coming from.
也就是说，我们也不知道氰化氢到底位于气体尘埃盘的哪个方位。
And that's a problem, because these temperate planets, they can't access hydrogen cyanide just anywhere,
这就比较麻烦了，因为对于适宜的行星来说，不是任何的氰化氢都有用，
but it must be fairly close to where they assemble for them to have access to it.
它们必须与行星的距离够近，才能被行星利用。
So to bring this home, let's think about an analogous example, that is, of cypress growing in the United States.
为了讲得更明白一点，我们来做个类比，就拿在美国种柏树来举例好了。
So let's say, hypothetically, that you've returned from Europe where you have seen beautiful Italian cypresses,
假设，你去了一趟欧洲，在那儿看到了美丽的意大利柏树，
and you want to understand, you know, does it make sense to import them to the United States.
于是你想知道把柏树引入到美国的可能性。
Could you grow them here? So you talk to the cypress experts,
你能在美国种柏树吗？于是你去咨询了柏树专家，
they tell you that there is indeed a band of not-too-hot, not-too-cold across the United States where you could grow them.
他们告诉你的确有一个横跨美国、气候温和的带状区域，能种植柏树。
And if you have a nice, high-resolution map or image like this,
如果你有一张像这样的完整高清的地图，
it's quite easy to see that this cypress strip overlaps with a lot of green fertile land pixels.
就不难发现这块适合柏树生长的带状区域覆盖了许多代表肥沃绿色植被带的像素点。
Even if I start degrading this map quite a bit, making it lower and lower resolution,
即使我降低地图的清晰度，一点一点降低它的分辨率，
it's still possible to tell that there's going to be some fertile land overlapping with this strip.
我们还是能看出有一些土壤肥沃的地带与带状区域重合。
But what about if the whole United States is incorporated into a single pixel? If the resolution is that low.
那么，如果整个美国被包含在一个像素点内呢？如果分辨率这么低，你怎么办？
What do you do now, how do you now tell whether you can grow cypresses in the United States?
现在你如何判断在美国的哪个区域能种植柏树？
Well the answer is you can't. I mean, there's definitely some fertile land there,
你无法判断。我们能确定那儿有一些适合的土壤，
or you wouldn't have that green tint to the pixel, but there's just no way of telling whether any of that green is in the right place.
否则图中的像素点不会是绿色的，但我们无法得知，绿色地带的具体位置。
And that is exactly the problem we were facing with our single-pixel images of these discs with hydrogen cyanide.
这就是当我们只能拍摄到含氰化氢的气体尘埃盘的单像素图像时所面临的问题。
So what we need is something analogous, at least those low-resolution maps that I just showed you,
所以，我们需要的也是类似的东西，至少也是一张低像素的图像，就像那张美国地图，
to be able to tell whether there's overlap between where the hydrogen cyanide is and where these planets can access it as they are forming.
使我们能够判断氰化氢所处的方位和形成中的行星之间是否存在重合。
So coming to the rescue, a few years ago, is this new, amazing, beautiful telescope ALMA,
那么我们在几年前找到的解决办法，就是这组无与伦比的新型ALMA望远镜，
the Atacama Large Millimeter and submillimeter Array in northern Chile.
位于智利北部的“阿塔卡马大型毫米波/亚毫米波阵列”。
So, ALMA is amazing in many different ways, but the one that I'm going to focus on is that,
ALMA在各个方面都卓越非凡，但我想着重讲的是，
as you can see, I call this one telescope, but you can there are actually many dishes in this image.
正如你们所见，我们称它为一个望远镜，但这张图里有许多个天线盘。
And this is a telescope that consists of 66 individual dishes that all work in unison.
这是一个拥有66座独立天线盘的望远镜，它们协同工作。
And that means that you have a telescope that is the size of the largest distance that you can put these dishes away from one another.
这就意味着，每座天线盘间隔的最大距离相加，就能得到这座望远镜的最大尺寸。
Which in ALMA's case are a few miles. So you have a more than mile-sized telescope.
也就是说，ALMA的尺寸可达好几英里。这是一座几英里大的望远镜。
And when you have such a big telescope, you can zoom in on really small things,
透过如此巨型的望远镜，你可以聚焦到非常细微的物体上，
including making maps of hydrogen cyanide in these planet-forming discs.
比如，绘制正在形成行星的气体尘埃盘里的氰化氢分布图。
So when ALMA came online a few years ago, that was one of the first things that I proposed that we use it for.
几年前当ALMA首次上线时，这就是我提议的项目之一。
And what does a map of hydrogen cyanide look like in a disc? Is the hydrogen cyanide at the right place?
那么，气体尘埃盘里的氰化氢分布图到底长什么样呢？氰化氢所在的方位合理吗？
And the answer is that it is. So this is the map.
答案是肯定的。这就是分布图。
You see the hydrogen cyanide emission being spread out across the disc.
你可以看到被释放的氰化氢分散在整个气体尘埃盘内。
First of all, it's almost everywhere, which is very good news.
几乎无处不在，这是个好消息。
But you have a lot of extra bright emission coming from close to the star towards the center of the disc.
而且你还可以看到一些特别光亮的释放物，从气体尘埃盘中心处的恒星散发出来。
And this is exactly where we want to see it. This is close to where these planets are forming.
这正是我们希望看到的氰化氢的位置。行星们将在这附近形成。
And this is not what we see just towards one disc -- here are three more examples.
不只一个气体尘埃盘呈现出了这样的景象，这儿还有三个例证。
You can see they all show the same thing -- lots of bright hydrogen cyanide emission coming from close to the center of the star.
你可以看到他们都展示了相同的现象--大量光亮的氰化氢从恒星的中心附近被释放出来。
For full disclosure, we don't always see this.
然而，情况不总是这样的。
There are discs where we see the opposite, where there's actually a hole in the emission towards the center.
我们也观察到一些情况相反的气体尘埃盘，它们的中心形成了一个氰化氢中空地带。
So this is the opposite of what we want to see, right?
这恰恰不是我们想要的，对吧？
This is not places where we could research if there is any hydrogen cyanide around where these planets are forming.
这不是我们所需要的氰化氢与正在形成的行星所重合的区域。
But in most cases, we just don't detect hydrogen cyanide, but we detect it in the right place. So what does all this mean?
但是，大多数情况下，我们不光探测氰化氢是否存在，还要看它是否存在于正确的位置。这一切意味着什么呢？
Well, I told you in the beginning that we have lots of these temperate planets, maybe a billion or so of them,
正如我在开场时所说的，宇宙中适宜的行星非常多，大约有十亿个，
that could have life develop on them if they have the right ingredients.
它们只要满足必需的物质条件，就可能出现生命。
And I've also shown that we think a lot of the time, the right ingredients are there
我也展示了在很多时候，必要的物质是存在的，
we have water, we have hydrogen cyanide, there will be other organic molecules as well coming with the cyanides.
我们发现了水和氰化氢，还有其他的有机分子随氰化物一起出现。
This means that planets with the most basic ingredients for life are likely to be incredibly common in our galaxy.
这说明能够孕育生命的行星可能在银河系中极其常见。
And if all it takes for life to develop is to have these basic ingredients available, there should be a lot of living planets out there.
那么，如果只要有这些基础物质，生命就会出现的话，拥有生命的行星应该是数不胜数。
But that is of course a big if. And I would say the challenge of the next decades, for both astronomy and chemistry,
但我说的是“如果”。我认为，在下一个十年，天文学和化学将面临的挑战是，
is to figure out just how often we go from having a potentially living planet to having an actually living one. Thank you.
我们将研究在可能孕育生命的行星里实际产生生命的行星的比率。谢谢大家。