Finding life we can't imagine | Christoph Adami

翻译人员: Chunxiang Qian 校对人员: Felix Chen

So, I have a strange career.

我的职业比较奇特

I know it because people come up to me, like colleagues, and say,

这么说是因为有人跑过来，比如我的同事

"Chris, you have a strange career."

他说：“克里斯，你的职业很奇特啊”

(Laughter)

（笑声）

And I can see their point,

我知道

because I started my career as a theoretical nuclear physicist.

这是因为我是从

理论核物理学家起家

And I was thinking about quarks and gluons and heavy ion collisions,

成天想的都是夸克、胶子

还有重离子碰撞

and I was only 14 years old --

那时只有14岁

No, no, I wasn't 14 years old.

不，不，我不是14岁

But after that,

不过自那以后

我有了我自己的实验室

I actually had my own lab

是在计算神经科学系

in the Computational Neuroscience department,

不过我没搞什么神经科学

and I wasn't doing any neuroscience.

Later, I would work on evolutionary genetics,

后来我开始研究进化基因学

and I would work on systems biology.

然后是组织生物学

But I'm going to tell you about something else today.

不过以上都不是今天要讲的

I'm going to tell you about how I learned something about life.

我要讲的是

我是如何研究生命的

And I was actually a rocket scientist.

我是个火箭科学家

I wasn't really a rocket scientist,

我不是真的火箭科学家

but I was working at the Jet Propulsion Laboratory

不过我为喷气推进实验室（JPL）

喷气推进实验室（JPL）工作

它位于温暖的加利福尼亚

in sunny California, where it's warm;

whereas now I am in the mid-West, and it's cold.

而我现在在中西部

天真冷

But it was an exciting experience.

不过是有趣的经历

One day, a NASA manager comes into my office,

一天一名NASA主管来到我的办公室

sits down and says,

坐下对我说

"Can you please tell us, how do we look for life outside Earth?"

“你能不能告诉我们

怎么寻找外星生命？”

我当时很惊讶

And that came as a surprise to me,

因为我是被雇来

because I was actually hired to work on quantum computation.

做量子计算的研究的

不过，我给了一个好答案

Yet, I had a very good answer.

I said, "I have no idea."

我说“我不知道”

(Laughter)

And he told me, "Biosignatures, we need to look for a biosignature."

他说“生命指标

我们要找生命指标”

我说，“那是什么？”

And I said, "What is that?"

And he said, "It's any measurable phenomenon

他说“就是任何可被测量的现象

能帮助我们发现

that allows us to indicate the presence of life."

生命的存在”

And I said, "Really?

我说“当真？”

Because isn't that easy?

因为那不是太简单了？

I mean, we have life.

我是说，我们有生命

Can't you apply a definition,

但你能为生命给出一个

for example, a Supreme Court-like definition of life?"

类似于最高法院的终极定义吗？

我想了想说

And then I thought about it a little bit, and I said,

“真就那么简单吗？”

"Well, is it really that easy?

因为你看到这个

Because, yes, if you see something like this,

then all right, fine, I'm going to call it life --

毫无疑问，我会称之为生命－

no doubt about it.

没问题

But here's something."

但是这个

And he goes, "Right, that's life too. I know that."

人们会说“没错，那也是生命，我知道”

Except, if you think that life is also defined by things that die,

但是，如果你觉得会死去的东西

是生命

you're not in luck with this thing,

那么这个怎么解释呢

because that's actually a very strange organism.

因为这是个非常奇怪的有机体

It grows up into the adult stage like that

进入成年期它呈这样

然后像本杰明·巴顿一样

and then goes through a Benjamin Button phase,

and actually goes backwards and backwards until it's like a little embryo again,

越长越小

直到又变成一个胎儿

然后再长大，再长回去，再长大——像悠悠球一样——

and then actually grows back up, and back down and back up --

永生不死

sort of yo-yo -- and it never dies.

So it's actually life,

这也是生命

但不象我们一般认为的

but it's actually not as we thought life would be.

生命形态

And then you see something like that.

你还能看到这样的东西

And he was like, "My God, what kind of a life form is that?"

人们会说“天哪，这是什么生命形态啊？”

有人知道吗？

Anyone know?

这不是生命，这是晶体

It's actually not life, it's a crystal.

所以当你观察的东西

So once you start looking and looking at smaller and smaller things --

越来越小－

so this particular person wrote a whole article and said,

这个人

他写了一篇文章说“这些是细菌”

"Hey, these are bacteria."

Except, if you look a little bit closer,

如果你凑近了看

you see, in fact, that this thing is way too small to be anything like that.

可以看到这个东西太小了不可能长成那样

他是被说服了

So he was convinced, but, in fact, most people aren't.

不过大部分人却没有

当然

And then, of course, NASA also had a big announcement,

NASA做了一个重大宣布

and President Clinton gave a press conference,

克林顿总统开了新闻发布会

宣布在火星陨石上

about this amazing discovery of life in a Martian meteorite.

发现了生命

不过近来这个观点备受质疑

Except that nowadays, it's heavily disputed.

如果你研究这些图片

If you take the lesson of all these pictures,

then you realize, well, actually, maybe it's not that easy.

你会意识到，也许这并不那么容易

也许我需要

Maybe I do need a definition of life

一个生命的定义

in order to make that kind of distinction.

来做区别

那生命能被定义吗？

So can life be defined?

你怎么说？

Well how would you go about it?

当然

Well of course, you'd go to Encyclopedia Britannica and open at L.

你会翻开大英百科全书的L部

不，你不会这么做，你会在Google搜索

No, of course you don't do that; you put it somewhere in Google.

或许会得到些什么

And then you might get something.

(Laughter)

And what you might get --

可能会得到——

and anything that actually refers to things that we are used to,

一切称我们习以为常的东西生命的

扔到一边去

you throw away.

然后你可能会得到这个

And then you might come up with something like this.

带着许多许多概念的

And it says something complicated with lots and lots of concepts.

复杂表述

到底谁写出

Who on Earth would write something as convoluted and complex and inane?

这么晦涩复杂

疯狂的东西？

但这确实是一堆很重要的概念

Oh, it's actually a really, really, important set of concepts.

我标出了几个词

So I'm highlighting just a few words

and saying definitions like that rely on things

这样的定义

不是基于氨基酸

that are not based on amino acids or leaves or anything that we are used to,

或者叶子

或者我们知道的任何东西

而是只基于过程

but in fact on processes only.

如果你仔细看下

And if you take a look at that,

这是我写的一本关于人工生命的书

this was actually in a book that I wrote that deals with artificial life.

它解释了

And that explains why that NASA manager was actually in my office to begin with.

那位NASA主管来到我办公室的原因

Because the idea was that, with concepts like that,

因为这样的想法，这样的概念

maybe we can actually manufacture a form of life.

我们可能创造出

一个生命形式

And so if you go and ask yourself, "What on Earth is artificial life?",

如果你反问自己

“到底什么是人工生命”

let me give you a whirlwind tour of how all this stuff came about.

让我带你快速了解一下

这是怎么弄出来的

And it started out quite a while ago,

很久以前

when someone wrote one of the first successful computer viruses.

有人写出了

最早的计算机病毒

对年纪还比较轻的人来说

And for those of you who aren't old enough,

you have no idea how this infection was working --

你可能不知道它是怎么感染的－

namely, through these floppy disks.

就是这个软盘

But the interesting thing about these computer virus infections

但感染电脑病毒有趣的是

如果你看看

was that, if you look at the rate at which the infection worked,

感染的速率

they show this spiky behavior that you're used to from a flu virus.

它们表现出这种上下波动

是在流感病毒上常见的

And it is in fact due to this arms race

事实上正是由于

between hackers and operating system designers

黑客和操作系统设计者间的军备竞赛

that things go back and forth.

表现出这样结果

And the result is kind of a tree of life of these viruses,

这个结果是这些病毒的

生命树形图

a phylogeny that looks very much like the type of life

一个看上去十分像我们熟悉的

生命的发展史，至少对病毒的层面来说

that we're used to, at least on the viral level.

So is that life?

那这是生命吗？至少我不这么认为

Not as far as I'm concerned.

为什么？因为它们不能自己演化

Why? Because these things don't evolve by themselves.

事实上，是黑客写出了它们

In fact, they have hackers writing them.

但是这个想法立刻被推进一步

But the idea was taken very quickly a little bit further,

when a scientist working at the Santa Fe Institute decided,

一个在新墨西哥州圣菲市的科学家决定

"Why don't we try to package these little viruses

“干嘛不把这些病毒

in artificial worlds inside of the computer

放到电脑的虚拟世界里

让它们自己演化呢？”

and let them evolve?"

And this was Steen Rasmussen.

这个科学家就是Steen Rasmussen

And he designed this system, but it really didn't work,

他设计了这个系统，但是不奏效

because his viruses were constantly destroying each other.

因为他的病毒不断互相摧毁

But there was another scientist who had been watching this, an ecologist.

但是当时还有一个科学家在关注此事，一个生态学家

他回了家说，“我知道怎么解决”

And he went home and says, "I know how to fix this."

And he wrote the Tierra system,

他写了Tierra系统

and, in my book,

在我的书里，是最早出现的

is in fact one of the first truly artificial living systems --

真正的虚拟生命系统之一——

except for the fact that these programs didn't really grow in complexity.

只是这些程序不会拥有复杂体

So having seen this work, worked a little bit on this,

看了这些研究，自己也多少涉猎一些

this is where I came in.

我开始了我的研究

And I decided to create a system that has all the properties

我决定创造一个系统

其属性必须支持

that are necessary to see, in fact, the evolution of complexity,

复杂体的进化

越来越多的复杂问题不断进化

more and more complex problems constantly evolving.

当然，因为我不知道怎么写代码，所以需要帮助

And of course, since I really don't know how to write code, I had help in this.

这是加州理工学院的

I had two undergraduate students

两个和我公事过的本科生

at California Institute of Technology that worked with me.

左边是Charles Offria，右边是Titus Brown

That's Charles Ofria on the left, Titus Brown on the right.

他们现在都是密歇根州立大学里

They are now, actually, respectable professors

at Michigan State University,

受人尊敬的教授

but I can assure you, back in the day, we were not a respectable team.

不过那时候

我们还不没有受尊敬的份儿

我很高兴那些我们三个人老粘在一起的照片

And I'm really happy that no photo survives

都没有保留下来

of the three of us anywhere close together.

这个系统什么样子

But what is this system like?

我没法深入讲解

Well I can't really go into the details,

but what you see here is some of the entrails.

但你这儿你可以看到一些细部

我着重要讲的

But what I wanted to focus on is this type of population structure.

是群体构造特征

这儿有大概一万个程序

There's about 10,000 programs sitting here.

And all different strains are colored in different colors.

每一个变种都用不同的颜色标记

And as you see here, there are groups that are growing on top of each other,

你可以看到群体会互相覆盖

因为它们在扩散

because they are spreading.

Any time there is a program that's better at surviving in this world,

任何时刻一个程序

因为获得某个突变

due to whatever mutation it has acquired,

从而在这个世界里更好的生存

it is going to spread over the others and drive the others to extinction.

那它讲不断扩散把其他程度逼入绝境

下面播放的这个短片你就可以看到这种变化

So I'm going to show you a movie

where you're going to see that kind of dynamic.

这个实验是从

And these kinds of experiments are started with programs that we wrote ourselves.

我们自己写的程序开始的

我们写了程序，复制了它们

We write our own stuff, replicate it, and are very proud of ourselves.

我们为此很骄傲

And we put them in, and what you see immediately

然后放到系统里，你马上可以看见的

is that there are waves and waves of innovation.

不断变化的波形

By the way, this is highly accelerated,

顺便提一下，这个是加速播放

so it's like a 1000 generations a second.

大概是一秒是一千代

But immediately, the system goes like, "What kind of dumb piece of code was this?

但是很快系统有了反应

“这是什么愚蠢的代码？

This can be improved upon in so many ways, so quickly."

这可以以很多种方式

很快地改善”

So you see waves of new types taking over the other types.

你可以看到新的类型

取代其他的

And this type of activity goes on for quite a while,

这种类型的活动持续一段时间

until the main easy things have been acquired by these programs.

直到这些程序都获得了主要的简单的东西

And then, you see sort of like a stasis coming on

然后有一段停滞期

where the system essentially waits

系统在等待

for a new type of innovation, like this one,

一种新的变化，像这个

which is going to spread over all the other innovations that were before

它将扩散

覆盖之前所有的变化

and is erasing the genes that it had before,

并消除之前的所有基因

until a new type of higher level of complexity has been achieved.

直到获得一种新的高层次的复杂体

And this process goes on and on and on.

这个过程会一致持续

So what we see here

所以我们看到的就是

is a system that lives in very much the way we're used to how life goes.

一个如同我们所知的

生命形式一样生存的系统

But what the NASA people had asked me really was,

但是是NASA的官员问我

“那这些人

"Do these guys have a biosignature?

有生命指标吗？

Can we measure this type of life?

我们能测量到这样的生命吗？

Because if we can,

因为如果我们能的话

maybe we have a chance of actually discovering life somewhere else

也许有机会发现其他形式的生命

without being biased by things like amino acids."

而不需要

依赖氨基酸”

So I said, "Well, perhaps we should construct a biosignature

我说，“也许我们应该构造

一个基于

based on life as a universal process.

作为通用过程的生命的生命指标

In fact, it should perhaps make use of the concepts that I developed

事实上，这得利用

我开发的概念

以了解

just in order to sort of capture what a simple living system might be."

简单的生命体是什么样的

我得出的——

And the thing I came up with --

I have to first give you an introduction about the idea,

首先我得介绍一下这个想法

and maybe that would be a meaning detector,

也许是个存在探测器

而不是生命探测器

rather than a life detector.

And the way we would do that --

操纵的方式是——

I would like to find out how I can distinguish text

我怎么区分一段文字

that was written by a million monkeys, as opposed to text that is in our books.

是一百万个猴子写的

还是我们的书

And I would like to do it in such a way

我会这么做

that I don't actually have to be able to read the language,

我并不去阅读它

因为我知道我无法做到

because I'm sure I won't be able to.

只要我知道存在某种字母表

As long as I know that there's some sort of alphabet.

这是一个猴子写的

So here would be a frequency plot

一段文字的

of how often you find each of the 26 letters of the alphabet

26个字母频度的

in a text written by random monkeys.

示意图

And obviously, each of these letters comes off about roughly equally frequent.

显然这些字母

出现的频率基本相等

但是如果你看看一段英文段落的字母分布的话

But if you now look at the same distribution in English texts,

it looks like that.

是这样的

And I'm telling you, this is very robust across English texts.

而且英语文字的这种现象非常明显

如果是法语的，会有些不一样

And if I look at French texts, it looks a little bit different,

或者是意大利语，德语

or Italian or German.

它们都有自己的频度分布

They all have their own type of frequency distribution,

但也都非常明显

but it's robust.

不论内容是关于政治还是科学

It doesn't matter whether it writes about politics or about science.

不管是一首诗

It doesn't matter whether it's a poem or whether it's a mathematical text.

还是数学内容

都有明显的标识

It's a robust signature,

并且很稳定

and it's very stable.

As long as our books are written in English --

只要我们的书是英语写的－

因为人们不断地写和再印－

because people are rewriting them and recopying them --

it's going to be there.

这个标识就存在

So that inspired me to think about, well, what if I try to use this idea

这促使我想到

如果我用这个法子

不是去探测随意的

in order, not to detect random texts from texts with meaning,

是否有意义的文字

but rather detect the fact that there is meaning

而是探测可标志生命的

in the biomolecules that make up life.

生物分子的存在

首先我问道：

But first I have to ask:

what are these building blocks,

组成的基本单位是什么，就像我展示给你的字母表，要素一样？

like the alphabet, elements that I showed you?

我们有很多不同选择

Well it turns out, we have many different alternatives

作为这种构造基础

for such a set of building blocks.

可以是氨基酸

We could use amino acids,

we could use nucleic acids, carboxylic acids, fatty acids.

核酸，羧酸或者不饱和脂肪酸

In fact, chemistry's extremely rich, and our body uses a lot of them.

事实上，化学物质十分丰富，我们的身体有很多

为了试验这个想法

So that we actually, to test this idea,

first took a look at amino acids and some other carboxylic acids.

我们首先研究了氨基酸和其他一些羧酸

这是结果

And here's the result.

Here is, in fact, what you get

这个结果

if you, for example, look at the distribution of amino acids

如果你观察一个彗星或者星际空间的

on a comet or in interstellar space or, in fact, in a laboratory,

或者一个实验室的

氨基酸分布

where you made very sure that in your primordial soup,

实验室的话得保证原始汤里

没有任何生命

there is no living stuff in there.

你能找到的大部分是甘氨酸和丙氨酸

What you find is mostly glycine and then alanine

还有其他一些

and there's some trace elements of the other ones.

That is also very robust --

这结果也非常明显——

what you find in systems like Earth

你可以在地球系统中

where there are amino acids, but there is no life.

找到氨基酸

但是没有生命

But suppose you take some dirt and dig through it

但是如果

采集一些土壤

and then put it into these spectrometers,

放到光谱仪里

because there's bacteria all over the place;

因为细菌的存在

or you take water anywhere on Earth,

或者采集地球上任何一处的水

因为水里富含生命

because it's teaming with life,

and you make the same analysis;

然后你做同样的分析

the spectrum looks completely different.

光谱结果完全不一样

当然仍然还有甘氨酸和丙氨酸

Of course, there is still glycine and alanine,

but in fact, there are these heavy elements, these heavy amino acids,

但是更重要的因素是大量的氨基酸

that are being produced because they are valuable to the organism.

它们对有机体非常重要

因而大量产生

而其他一些

And some other ones that are not used in the set of 20,

没有在20个集合被使用

因为不在任何一个聚集里

they will not appear at all in any type of concentration.

出现

So this also turns out to be extremely robust.

这个结果特征也非常明显

It doesn't matter what kind of sediment you're using to grind up,

不管你是研磨是哪种泥沙

不管是细菌，植物或者动物

whether it's bacteria or any other plants or animals.

到处都有生命存在

Anywhere there's life,

you're going to have this distribution,

就会得出这样的分布

as opposed to that distribution.

而不是那样的

And it is detectable not just in amino acids.

不光是氨基酸可被探测

Now you could ask:

现在你会问：

Well, what about these Avidians?

那么Avidian呢？（一台叫Avida计算机里的数字生物物种）

Avidian是计算机世界的居民

The Avidians being the denizens of this computer world

where they are perfectly happy replicating and growing in complexity.

它们在那里快乐得繁殖成长

So this is the distribution that you get if, in fact, there is no life.

这是它们的分布

不是生命

They have about 28 of these instructions.

它们有28个这样的结构

And if you have a system where they're being replaced one by the other,

如果有一个供他们相互取代的系统

就像是猴子用打字机写作

it's like the monkeys writing on a typewriter.

每一个结构

Each of these instructions appears with roughly the equal frequency.

出现的频率基本一样

But if you now take a set of replicating guys

但是如果是像刚刚视频里

那些复制的家伙

like in the video that you saw,

则是这样

it looks like this.

这里有些结构

So there are some instructions

that are extremely valuable to these organisms,

是机体里非常脆弱的部分

他们的频度很高

and their frequency is going to be high.

And there's actually some instructions that you only use once, if ever.

而有些

你只能用一次，如果要用的话

So they are either poisonous

它们不是有毒

or really should be used at less of a level than random.

就是应该以低于随机的水平使用

In this case, the frequency is lower.

这种情况下，频度较低

那我们看到，这是个明显的生命指标吗？

And so now we can see, is that really a robust signature?

I can tell you indeed it is,

是的

because this type of spectrum, just like what you've seen in books,

因为这种分布，就如刚刚的书

and just like what you've seen in amino acids,

和氨基酸一样

it doesn't really matter how you change the environment,

不管你怎么改变环境，特征十分明显

it's very robust, it's going to reflect the environment.

会反映环境

现在给你们看一个我们做的实验

So I'm going to show you now a little experiment that we did.

得解释一下

And I have to explain to you,

图表的上部

the top of this graph

shows you that frequency distribution that I talked about.

是我提到的频度分布

Here, that's the lifeless environment

这是无生命的环境

每一个结构的

where each instruction occurs at an equal frequency.

频度相等

下面的

And below there, I show, in fact, the mutation rate in the environment.

是环境里的突变率

And I'm starting this at a mutation rate that is so high

我将开始的突变率设得很高

that even if you would drop a replicating program

高到就算你放入

一个复制程序

that would otherwise happily grow up to fill the entire world,

能快乐的成长

并布满整个空间

如果你放进去，立刻突变至死亡

if you drop it in, it gets mutated to death immediately.

So there is no life possible at that type of mutation rate.

所以那样的突变率

任何生命无法存活

But then I'm going to slowly turn down the heat, so to speak,

但是我降低了温度

and then there's this viability threshold

到这个可行阈值

where now it would be possible for a replicator to actually live.

这样有一个复制体

能够存活

And indeed, we're going to be dropping these guys into that soup all the time.

我们把这些家伙放进

（原始）汤里

是什么样子呢

So let's see what that looks like.

开始的时候什么都没有

So first, nothing, nothing, nothing.

太热了太热了

Too hot, too hot.

Now the viability threshold is reached,

达到可行阈值之后

and the frequency distribution has dramatically changed

频度分布

开始剧烈变化然后稳定下来

and, in fact, stabilizes.

然后我就

And now what I did there

is, I was being nasty, I just turned up the heat again and again.

很邪恶地调高了温度

当然到达了可行阈值

And of course, it reaches the viability threshold.

And I'm just showing this to you again because it's so nice.

我再给你们看一遍因为这个太棒了

You hit the viability threshold.

降到可行阈值

The distribution changes to "alive!"

分布就变成“有生命的”

And then, once you hit the threshold

升高到可行阈值

where the mutation rate is so high that you cannot self-reproduce,

突变率太高了

就无法自我繁殖

不能将信息

you cannot copy the information forward to your offspring

没有错误地

without making so many mistakes that your ability to replicate vanishes.

复制给后代

复制的能力就消失了

And then, that signature is lost.

然后生命指标消失了

就此我们学到什么？

What do we learn from that?

Well, I think we learn a number of things from that.

我觉得我们学到几点

One of them is,

第一是

if we are able to think about life in abstract terms --

如果我们可以

从抽象意义上认知生命－

and we're not talking about things like plants,

我们不是在讨论植物

也不是氨基酸

and we're not talking about amino acids,

或者细菌

and we're not talking about bacteria,

but we think in terms of processes --

而是一种过程——

那么我们可以认为生命

then we could start to think about life

not as something that is so special to Earth,

不是地球特有的

but that, in fact, could exist anywhere.

可能存在任何一个地方

Because it really only has to do with these concepts of information,

因为它只是

与信息的概念有关

of storing information within physical substrates --

与储存信息有关

通过物质性基板——

anything: bits, nucleic acids, anything that's an alphabet --

任何东西：数位，核酸

任何类似字母表的东西——

and make sure that there's some process

并确保存在某种程序

so that this information can be stored for much longer than you would expect --

从而信息可以被长久保存

比你预期的信息损坏的

时间尺度还要长很多

the time scales for the deterioration of information.

如果是这样

And if you can do that, then you have life.

那么就是生命

So the first thing that we learn

所以头一件我们学到的

is that it is possible to define life in terms of processes alone,

就是生命可以被定义为

一种过程本身

without referring at all to the type of things that we hold dear,

而不需要借助

其他我们珍视的东西

比如地球上的生命形式

as far as the type of life on Earth is.

And that, in a sense, removes us again,

这个结论再一次

like all of our scientific discoveries, or many of them --

就像其他所有科学发现，或者很多科学发现－

it's this continuous dethroning of man --

告诉人们－

我们的存在并不是什么独特的事

of how we think we're special because we're alive.

Well, we can make life; we can make life in the computer.

我们可以创造生命，可以在电脑里创造生命

Granted, it's limited,

当然这个有限

but we have learned what it takes in order to actually construct it.

但是我们据此可以知道

构建生命的要素

And once we have that,

一旦我们有这些要素

then it is not such a difficult task anymore

那么创造生命不是什么难事

to say, if we understand the fundamental processes

如果我们掌握了最基本的

that do not refer to any particular substrate,

不借助于任何特殊基板的过程的话

then we can go out and try other worlds,

我们就能走出去

探寻其他世界

figure out what kind of chemical alphabets might there be,

了解那里有什么样的化学字母表

了解一般的化学物质

figure enough about the normal chemistry, the geochemistry of the planet,

和那个星球的地理化学

那样我们就知道没有生命的

so that we know what this distribution would look like in the absence of life,

分布是什么样子

and then look for large deviations from this --

从而以此寻找更大的偏差－

this thing sticking out, which says, "This chemical really shouldn't be there."

这个突起意味着

“这个化学物质不应该在这儿”

Now we don't know that there's life then,

现在我们还不知道那里有没有生命

but we could say,

但是我们可以说

"Well at least I'm going to have to take a look very precisely at this chemical

“至少我会精确地研究一下这个化学物质

and see where it comes from."

看看哪里来的”

这也许就是

And that might be our chance of actually discovering life

当我们无法看到生命

when we cannot visibly see it.

但真正发现生命的机会

And so that's really the only take-home message that I have for you.

这是我唯一的可以让你

带回家的信息

Life can be less mysterious than we make it out to be

生命并不一定像

我们以为的那样神秘

when we try to think about how it would be on other planets.

如果我们知道其他星球上也存在的话

And if we remove the mystery of life,

如果我们去掉生命的神秘感

then I think it is a little bit easier for us to think about how we live,

我像对于我们

思考如何生活

and how perhaps we're not as special as we always think we are.

和我们并不特殊来说会更容易

And I'm going to leave you with that.

这就是我要讲的

非常感谢

And thank you very much.

(Applause)

（掌声）