TEDxUIUC
Christoph Adami: Finding life we can't imagine
克利斯朵夫･阿达米：寻找难以想象的生命
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如果外星人根本不是我们所知的生命形态，那么我们如何搜寻外星人？在TEDxUIUC上，克利斯朵夫･阿达米告诉我们他是如何通过人工生命形式的研究 —— 即自我复制的电脑程序－来找到一个标识，一个“生命标记”的。这完全抛开了我们对所谓生命的先入为主的理解。
Christoph Adami - Artificial life researcher
Christoph Adami works on the nature of life and evolution, trying to define life in a way that is as free as possible from our preconceptions. Full bio
Christoph Adami works on the nature of life and evolution, trying to define life in a way that is as free as possible from our preconceptions. Full bio
Double-click the English transcript below to play the video.
00:15
So I have a strange career.
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我的职业比较奇特
00:17
I know it because people come up to me, like colleagues,
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这么说是因为有人跑过来，比如我的同事
00:20
and say, "Chris, you have a strange career."
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他说：“克里斯，你的职业很奇特啊”
00:22
(Laughter)
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（笑声）
00:24
And I can see their point,
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我知道
00:26
because I started my career
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这是因为我是从
00:28
as a theoretical nuclear physicist.
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理论核物理学家起家
00:30
And I was thinking about quarks and gluons
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成天想的都是夸克、胶子
00:32
and heavy ion collisions,
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还有重离子碰撞
00:34
and I was only 14 years old.
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那时只有14岁
00:36
No, no, I wasn't 14 years old.
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不，不，我不是14岁
00:40
But after that,
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不过自那以后
00:42
I actually had my own lab
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我有了我自己的实验室
00:44
in the computational neuroscience department,
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是在计算神经科学系
00:46
and I wasn't doing any neuroscience.
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不过我没搞什么神经科学
00:48
Later, I would work on evolutionary genetics,
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后来我开始研究进化基因学
00:51
and I would work on systems biology.
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然后是组织生物学
00:53
But I'm going to tell you about something else today.
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不过以上都不是今天要讲的
00:56
I'm going to tell you
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我要讲的是
00:58
about how I learned something about life.
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我是如何研究生命的
01:00
And I was actually a rocket scientist.
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我是个火箭科学家
01:04
I wasn't really a rocket scientist,
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我不是真的火箭科学家
01:06
but I was working
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不过我为喷气推进实验室（JPL）
01:08
at the Jet Propulsion Laboratory
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喷气推进实验室（JPL）工作
01:10
in sunny California where it's warm;
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它位于温暖的加利福尼亚
01:13
whereas now I'm in the mid-West,
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而我现在在中西部
01:15
and it's cold.
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天真冷
01:17
But it was an exciting experience.
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不过是有趣的经历
01:20
One day a NASA manager comes into my office,
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一天一名NASA主管来到我的办公室
01:23
sits down and says,
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坐下对我说
01:26
"Can you please tell us,
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“你能不能告诉我们
01:28
how do we look for life outside Earth?"
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怎么寻找外星生命？”
01:30
And that came as a surprise to me,
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我当时很惊讶
01:32
because I was actually hired
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因为我是被雇来
01:34
to work on quantum computation.
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做量子计算的研究的
01:36
Yet, I had a very good answer.
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不过，我给了一个好答案
01:38
I said, "I have no idea."
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我说“我不知道”
01:41
And he told me, "Biosignatures,
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他说“生命指标
01:44
we need to look for a biosignature."
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我们要找生命指标”
01:46
And I said, "What is that?"
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我说，“那是什么？”
01:48
And he said, "It's any measurable phenomenon
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他说“就是任何可被测量的现象
01:50
that allows us to indicate
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能帮助我们发现
01:52
the presence of life."
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生命的存在”
01:54
And I said, "Really?
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我说“当真？”
01:56
Because isn't that easy?
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因为那不是太简单了？
01:58
I mean, we have life.
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我是说，我们有生命
02:00
Can't you apply a definition,
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但你能为生命给出一个
02:02
like for example, a Supreme Court-like definition of life?"
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类似于最高法院的终极定义吗？
02:06
And then I thought about it a little bit, and I said,
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我想了想说
02:08
"Well, is it really that easy?
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“真就那么简单吗？”
02:10
Because, yes, if you see something like this,
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因为你看到这个
02:13
then all right, fine, I'm going to call it life --
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毫无疑问，我会称之为生命－
02:15
no doubt about it.
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没问题
02:17
But here's something."
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但是这个
02:19
And he goes, "Right, that's life too. I know that."
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人们会说“没错，那也是生命，我知道”
02:22
Except, if you think life is also defined
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但是，如果你觉得会死去的东西
02:24
by things that die,
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是生命
02:26
you're not in luck with this thing,
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那么这个怎么解释呢
02:28
because that's actually a very strange organism.
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因为这是个非常奇怪的有机体
02:30
It grows up into the adult stage like that
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进入成年期它呈这样
02:32
and then goes through a Benjamin Button phase,
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然后像本杰明·巴顿一样
02:35
and actually goes backwards and backwards
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越长越小
02:37
until it's like a little embryo again,
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直到又变成一个胎儿
02:39
and then actually grows back up, and back down and back up -- sort of yo-yo --
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然后再长大，再长回去，再长大——像悠悠球一样——
02:42
and it never dies.
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永生不死
02:44
So it's actually life,
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这也是生命
02:46
but it's actually not
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但不象我们一般认为的
02:48
as we thought life would be.
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生命形态
02:51
And then you see something like that.
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你还能看到这样的东西
02:53
And he was like, "My God, what kind of a life form is that?"
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人们会说“天哪，这是什么生命形态啊？”
02:55
Anyone know?
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有人知道吗？
02:57
It's actually not life, it's a crystal.
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这不是生命，这是晶体
03:00
So once you start looking and looking
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所以当你观察的东西
03:02
at smaller and smaller things --
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越来越小－
03:04
so this particular person
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这个人
03:06
wrote a whole article and said, "Hey, these are bacteria."
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他写了一篇文章说“这些是细菌”
03:09
Except, if you look a little bit closer,
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如果你凑近了看
03:11
you see, in fact, that this thing is way too small to be anything like that.
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可以看到这个东西太小了不可能长成那样
03:14
So he was convinced,
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他是被说服了
03:16
but, in fact, most people aren't.
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不过大部分人却没有
03:18
And then, of course,
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当然
03:20
NASA also had a big announcement,
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NASA做了一个重大宣布
03:22
and President Clinton gave a press conference,
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克林顿总统开了新闻发布会
03:24
about this amazing discovery
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宣布在火星陨石上
03:26
of life in a Martian meteorite.
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发现了生命
03:29
Except that nowadays, it's heavily disputed.
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不过近来这个观点备受质疑
03:33
If you take the lesson of all these pictures,
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如果你研究这些图片
03:36
then you realize, well actually maybe it's not that easy.
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你会意识到，也许这并不那么容易
03:38
Maybe I do need
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也许我需要
03:40
a definition of life
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一个生命的定义
03:42
in order to make that kind of distinction.
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来做区别
03:44
So can life be defined?
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那生命能被定义吗？
03:46
Well how would you go about it?
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你怎么说？
03:48
Well of course,
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当然
03:50
you'd go to Encyclopedia Britannica and open at L.
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你会翻开大英百科全书的L部
03:52
No, of course you don't do that; you put it somewhere in Google.
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不，你不会这么做，你会在Google搜索
03:55
And then you might get something.
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或许会得到些什么
03:58
And what you might get --
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可能会得到——
04:00
and anything that actually refers to things that we are used to,
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一切称我们习以为常的东西生命的
04:02
you throw away.
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扔到一边去
04:04
And then you might come up with something like this.
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然后你可能会得到这个
04:06
And it says something complicated
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带着许多许多概念的
04:08
with lots and lots of concepts.
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复杂表述
04:10
Who on Earth would write something
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到底谁写出
04:12
as convoluted and complex
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这么晦涩复杂
04:14
and inane?
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疯狂的东西？
04:17
Oh, it's actually a really, really, important set of concepts.
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但这确实是一堆很重要的概念
04:21
So I'm highlighting just a few words
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我标出了几个词
04:24
and saying definitions like that
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这样的定义
04:26
rely on things that are not based
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不是基于氨基酸
04:28
on amino acids or leaves
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或者叶子
04:31
or anything that we are used to,
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或者我们知道的任何东西
04:33
but in fact on processes only.
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而是只基于过程
04:35
And if you take a look at that,
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如果你仔细看下
04:37
this was actually in a book that I wrote that deals with artificial life.
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这是我写的一本关于人工生命的书
04:40
And that explains why
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它解释了
04:42
that NASA manager was actually in my office to begin with.
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那位NASA主管来到我办公室的原因
04:45
Because the idea was that, with concepts like that,
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因为这样的想法，这样的概念
04:48
maybe we can actually manufacture
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我们可能创造出
04:50
a form of life.
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一个生命形式
04:52
And so if you go and ask yourself,
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如果你反问自己
04:55
"What on Earth is artificial life?",
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“到底什么是人工生命”
04:57
let me give you a whirlwind tour
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让我带你快速了解一下
04:59
of how all this stuff came about.
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这是怎么弄出来的
05:01
And it started out quite a while ago
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很久以前
05:04
when someone wrote
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有人写出了
05:06
one of the first successful computer viruses.
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最早的计算机病毒
05:08
And for those of you who aren't old enough,
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对年纪还比较轻的人来说
05:11
you have no idea how this infection was working --
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你可能不知道它是怎么感染的－
05:14
namely, through these floppy disks.
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就是这个软盘
05:16
But the interesting thing about these computer virus infections
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但感染电脑病毒有趣的是
05:19
was that, if you look at the rate
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如果你看看
05:21
at which the infection worked,
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感染的速率
05:23
they show this spiky behavior
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它们表现出这种上下波动
05:25
that you're used to from a flu virus.
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是在流感病毒上常见的
05:28
And it is in fact due to this arms race
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事实上正是由于
05:30
between hackers and operating system designers
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黑客和操作系统设计者间的军备竞赛
05:33
that things go back and forth.
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表现出这样结果
05:35
And the result is kind of a tree of life
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这个结果是这些病毒的
05:37
of these viruses,
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生命树形图
05:39
a phylogeny that looks very much
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一个看上去十分像我们熟悉的
05:42
like the type of life that we're used to, at least on the viral level.
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生命的发展史，至少对病毒的层面来说
05:45
So is that life? Not as far as I'm concerned.
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那这是生命吗？至少我不这么认为
05:48
Why? Because these things don't evolve by themselves.
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为什么？因为它们不能自己演化
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In fact, they have hackers writing them.
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事实上，是黑客写出了它们
05:53
But the idea was taken very quickly a little bit further
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但是这个想法立刻被推进一步
05:57
when a scientist working at the Scientific Institute decided,
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一个在科学研究所的科学家决定
06:00
"Why don't we try to package these little viruses
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“干嘛不把这些病毒
06:03
in artificial worlds inside of the computer
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放到电脑的虚拟世界里
06:05
and let them evolve?"
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让它们自己演化呢？”
06:07
And this was Steen Rasmussen.
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这个科学家就是Steen Rasmussen
06:09
And he designed this system, but it really didn't work,
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他设计了这个系统，但是不奏效
06:11
because his viruses were constantly destroying each other.
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因为他的病毒不断互相摧毁
06:14
But there was another scientist who had been watching this, an ecologist.
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但是当时还有一个科学家在关注此事，一个生态学家
06:17
And he went home and says, "I know how to fix this."
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他回了家说，“我知道怎么解决”
06:20
And he wrote the Tierra system,
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他写了Tierra系统
06:22
and, in my book, is in fact one of the first
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在我的书里，是最早出现的
06:25
truly artificial living systems --
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真正的虚拟生命系统之一——
06:27
except for the fact that these programs didn't really grow in complexity.
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只是这些程序不会拥有复杂体
06:30
So having seen this work, worked a little bit on this,
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看了这些研究，自己也多少涉猎一些
06:33
this is where I came in.
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我开始了我的研究
06:35
And I decided to create a system
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我决定创造一个系统
06:37
that has all the properties that are necessary
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其属性必须支持
06:39
to see the evolution of complexity,
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复杂体的进化
06:42
more and more complex problems constantly evolving.
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越来越多的复杂问题不断进化
06:45
And of course, since I really don't know how to write code, I had help in this.
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当然，因为我不知道怎么写代码，所以需要帮助
06:48
I had two undergraduate students
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这是加州理工学院的
06:50
at California Institute of Technology that worked with me.
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两个和我公事过的本科生
06:53
That's Charles Offria on the left, Titus Brown on the right.
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左边是Charles Offria，右边是Titus Brown
06:56
They are now actually respectable professors
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他们现在都是密歇根州立大学里
06:59
at Michigan State University,
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受人尊敬的教授
07:01
but I can assure you, back in the day,
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不过那时候
07:03
we were not a respectable team.
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我们还不没有受尊敬的份儿
07:05
And I'm really happy that no photo survives
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我很高兴那些我们三个人老粘在一起的照片
07:07
of the three of us anywhere close together.
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都没有保留下来
07:10
But what is this system like?
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这个系统什么样子
07:12
Well I can't really go into the details,
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我没法深入讲解
07:15
but what you see here is some of the entrails.
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但你这儿你可以看到一些细部
07:17
But what I wanted to focus on
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我着重要讲的
07:19
is this type of population structure.
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是群体构造特征
07:21
There's about 10,000 programs sitting here.
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这儿有大概一万个程序
07:24
And all different strains are colored in different colors.
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每一个变种都用不同的颜色标记
07:27
And as you see here, there are groups that are growing on top of each other,
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你可以看到群体会互相覆盖
07:30
because they are spreading.
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因为它们在扩散
07:32
Any time there is a program
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任何时刻一个程序
07:34
that's better at surviving in this world,
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因为获得某个突变
07:36
due to whatever mutation it has acquired,
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从而在这个世界里更好的生存
07:38
it is going to spread over the others and drive the others to extinction.
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那它讲不断扩散把其他程度逼入绝境
07:41
So I'm going to show you a movie where you're going to see that kind of dynamic.
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下面播放的这个短片你就可以看到这种变化
07:44
And these kinds of experiments are started
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这个实验是从
07:47
with programs that we wrote ourselves.
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我们自己写的程序开始的
07:49
We write our own stuff, replicate it,
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我们写了程序，复制了它们
07:51
and are very proud of ourselves.
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我们为此很骄傲
07:53
And we put them in, and what you see immediately
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然后放到系统里，你马上可以看见的
07:56
is that there are waves and waves of innovation.
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不断变化的波形
07:59
By the way, this is highly accelerated,
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顺便提一下，这个是加速播放
08:01
so it's like a thousand generations a second.
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大概是一秒是一千代
08:03
But immediately the system goes like,
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但是很快系统有了反应
08:05
"What kind of dumb piece of code was this?
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“这是什么愚蠢的代码？
08:07
This can be improved upon in so many ways
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这可以以很多种方式
08:09
so quickly."
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很快地改善”
08:11
So you see waves of new types
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你可以看到新的类型
08:13
taking over the other types.
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取代其他的
08:15
And this type of activity goes on for quite awhile,
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这种类型的活动持续一段时间
08:18
until the main easy things have been acquired by these programs.
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直到这些程序都获得了主要的简单的东西
08:22
And then you see sort of like a stasis coming on
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然后有一段停滞期
08:26
where the system essentially waits
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系统在等待
08:28
for a new type of innovation, like this one,
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一种新的变化，像这个
08:31
which is going to spread
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它将扩散
08:33
over all the other innovations that were before
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覆盖之前所有的变化
08:35
and is erasing the genes that it had before,
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并消除之前的所有基因
08:38
until a new type of higher level of complexity has been achieved.
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直到获得一种新的高层次的复杂体
08:42
And this process goes on and on and on.
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这个过程会一致持续
08:45
So what we see here
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所以我们看到的就是
08:47
is a system that lives
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一个如同我们所知的
08:49
in very much the way we're used to life [going.]
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生命形式一样生存的系统
08:51
But what the NASA people had asked me really
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但是是NASA的官员问我
08:55
was, "Do these guys
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“那这些人
08:57
have a biosignature?
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有生命指标吗？
08:59
Can we measure this type of life?
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我们能测量到这样的生命吗？
09:01
Because if we can,
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因为如果我们能的话
09:03
maybe we have a chance of actually discovering life somewhere else
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也许有机会发现其他形式的生命
09:06
without being biased
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而不需要
09:08
by things like amino acids."
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依赖氨基酸”
09:10
So I said, "Well, perhaps we should construct
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我说，“也许我们应该构造
09:13
a biosignature
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一个基于
09:15
based on life as a universal process.
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作为通用过程的生命的生命指标
09:18
In fact, it should perhaps make use
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事实上，这得利用
09:20
of the concepts that I developed
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我开发的概念
09:22
just in order to sort of capture
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以了解
09:24
what a simple living system might be."
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简单的生命体是什么样的
09:26
And the thing I came up with --
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我得出的——
09:28
I have to first give you an introduction about the idea,
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首先我得介绍一下这个想法
09:32
and maybe that would be a meaning detector,
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也许是个存在探测器
09:35
rather than a life detector.
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而不是生命探测器
09:38
And the way we would do that --
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操纵的方式是——
09:40
I would like to find out how I can distinguish
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我怎么区分一段文字
09:42
text that was written by a million monkeys,
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是一百万个猴子写的
09:44
as opposed to text that [is] in our books.
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还是我们的书
09:47
And I would like to do it in such a way
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我会这么做
09:49
that I don't actually have to be able to read the language,
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我并不去阅读它
09:51
because I'm sure I won't be able to.
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因为我知道我无法做到
09:53
As long as I know that there's some sort of alphabet.
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只要我知道存在某种字母表
09:55
So here would be a frequency plot
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这是一个猴子写的
09:58
of how often you find
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一段文字的
10:00
each of the 26 letters of the alphabet
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26个字母频度的
10:02
in a text written by random monkeys.
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示意图
10:05
And obviously each of these letters
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显然这些字母
10:07
comes off about roughly equally frequent.
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出现的频率基本相等
10:09
But if you now look at the same distribution in English texts,
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但是如果你看看一段英文段落的字母分布的话
10:13
it looks like that.
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是这样的
10:15
And I'm telling you, this is very robust across English texts.
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而且英语文字的这种现象非常明显
10:18
And if I look at French texts, it looks a little bit different,
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如果是法语的，会有些不一样
10:20
or Italian or German.
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或者是意大利语，德语
10:22
They all have their own type of frequency distribution,
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它们都有自己的频度分布
10:25
but it's robust.
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但也都非常明显
10:27
It doesn't matter whether it writes about politics or about science.
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不论内容是关于政治还是科学
10:30
It doesn't matter whether it's a poem
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不管是一首诗
10:33
or whether it's a mathematical text.
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还是数学内容
10:36
It's a robust signature,
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都有明显的标识
10:38
and it's very stable.
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并且很稳定
10:40
As long as our books are written in English --
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只要我们的书是英语写的－
10:42
because people are rewriting them and recopying them --
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因为人们不断地写和再印－
10:45
it's going to be there.
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这个标识就存在
10:47
So that inspired me to think about,
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这促使我想到
10:49
well, what if I try to use this idea
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如果我用这个法子
10:52
in order, not to detect random texts
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不是去探测随意的
10:54
from texts with meaning,
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是否有意义的文字
10:56
but rather detect the fact that there is meaning
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而是探测可标志生命的
11:00
in the biomolecules that make up life.
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生物分子的存在
11:02
But first I have to ask:
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首先我问道：
11:04
what are these building blocks, like the alphabet, elements that I showed you?
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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？
11:07
Well it turns out, we have many different alternatives
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我们有很多不同选择
11:10
for such a set of building blocks.
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作为这种构造基础
11:12
We could use amino acids,
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可以是氨基酸
11:14
we could use nucleic acids, carboxylic acids, fatty acids.
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核酸，羧酸或者不饱和脂肪酸
11:17
In fact, chemistry's extremely rich, and our body uses a lot of them.
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事实上，化学物质十分丰富，我们的身体有很多
11:20
So that we actually, to test this idea,
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为了试验这个想法
11:23
first took a look at amino acids and some other carboxylic acids.
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我们首先研究了氨基酸和其他一些羧酸
11:26
And here's the result.
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这是结果
11:28
Here is, in fact, what you get
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这个结果
11:31
if you, for example, look at the distribution of amino acids
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如果你观察一个彗星或者星际空间的
11:34
on a comet or in interstellar space
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或者一个实验室的
11:37
or, in fact, in a laboratory,
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氨基酸分布
11:39
where you made very sure that in your primordial soup
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实验室的话得保证原始汤里
11:41
that there is not living stuff in there.
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没有任何生命
11:43
What you find is mostly glycine and then alanine
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你能找到的大部分是甘氨酸和丙氨酸
11:46
and there's some trace elements of the other ones.
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还有其他一些
11:49
That is also very robust --
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这结果也非常明显——
11:52
what you find in systems like Earth
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你可以在地球系统中
11:55
where there are amino acids,
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找到氨基酸
11:57
but there is no life.
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但是没有生命
11:59
But suppose you take some dirt
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但是如果
12:01
and dig through it
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采集一些土壤
12:03
and then put it into these spectrometers,
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放到光谱仪里
12:06
because there's bacteria all over the place;
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因为细菌的存在
12:08
or you take water anywhere on Earth,
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或者采集地球上任何一处的水
12:10
because it's teaming with life,
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因为水里富含生命
12:12
and you make the same analysis;
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然后你做同样的分析
12:14
the spectrum looks completely different.
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光谱结果完全不一样
12:16
Of course, there is still glycine and alanine,
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当然仍然还有甘氨酸和丙氨酸
12:20
but in fact, there are these heavy elements, these heavy amino acids,
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但是更重要的因素是大量的氨基酸
12:23
that are being produced
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它们对有机体非常重要
12:25
because these are valuable to the organism.
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因而大量产生
12:27
And some other ones
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而其他一些
12:29
that are not used in the set of 20,
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没有在20个集合被使用
12:31
they will not appear at all
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因为不在任何一个聚集里
12:33
in any type of concentration.
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出现
12:35
So this also turns out to be extremely robust.
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这个结果特征也非常明显
12:37
It doesn't matter what kind of sediment you're using to grind up,
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不管你是研磨是哪种泥沙
12:40
whether it's bacteria or any other plants or animals.
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不管是细菌，植物或者动物
12:43
Anywhere there's life,
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到处都有生命存在
12:45
you're going to have this distribution,
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就会得出这样的分布
12:47
as opposed to that distribution.
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而不是那样的
12:49
And it is detectable not just in amino acids.
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不光是氨基酸可被探测
12:52
Now you could ask:
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现在你会问：
12:54
well, what about these Avidians?
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那么Avidian呢？（一台叫Avida计算机里的数字生物物种）
12:56
The Avidians being the denizens of this computer world
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Avidian是计算机世界的居民
13:00
where they are perfectly happy replicating and growing in complexity.
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它们在那里快乐得繁殖成长
13:03
So this is the distribution that you get
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这是它们的分布
13:06
if, in fact, there is no life.
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不是生命
13:08
They have about 28 of these instructions.
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它们有28个这样的结构
13:11
And if you have a system where they're being replaced one by the other,
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如果有一个供他们相互取代的系统
13:14
it's like the monkeys writing on a typewriter.
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就像是猴子用打字机写作
13:16
Each of these instructions appears
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每一个结构
13:19
with roughly the equal frequency.
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出现的频率基本一样
13:22
But if you now take a set of replicating guys
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但是如果是像刚刚视频里
13:26
like in the video that you saw,
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那些复制的家伙
13:28
it looks like this.
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则是这样
13:30
So there are some instructions
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这里有些结构
13:32
that are extremely valuable to these organisms,
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是机体里非常脆弱的部分
13:34
and their frequency is going to be high.
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他们的频度很高
13:37
And there's actually some instructions
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而有些
13:39
that you only use once, if ever.
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你只能用一次，如果要用的话
13:41
So they are either poisonous
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它们不是有毒
13:43
or really should be used at less of a level than random.
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就是应该以低于随机的水平使用
13:47
In this case, the frequency is lower.
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这种情况下，频度较低
13:50
And so now we can see, is that really a robust signature?
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那我们看到，这是个明显的生命指标吗？
13:53
I can tell you indeed it is,
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是的
13:55
because this type of spectrum, just like what you've seen in books,
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因为这种分布，就如刚刚的书
13:58
and just like what you've seen in amino acids,
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和氨基酸一样
14:00
it doesn't really matter how you change the environment, it's very robust;
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不管你怎么改变环境，特征十分明显
14:03
it's going to reflect the environment.
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会反映环境
14:05
So I'm going to show you now a little experiment that we did.
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现在给你们看一个我们做的实验
14:07
And I have to explain to you,
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得解释一下
14:09
the top of this graph
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图表的上部
14:11
shows you that frequency distribution that I talked about.
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是我提到的频度分布
14:14
Here, in fact, that's the lifeless environment
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这是无生命的环境
14:17
where each instruction occurs
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每一个结构的
14:19
at an equal frequency.
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频度相等
14:21
And below there, I show, in fact,
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下面的
14:24
the mutation rate in the environment.
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是环境里的突变率
14:27
And I'm starting this at a mutation rate that is so high
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我将开始的突变率设得很高
14:30
that, even if you would drop
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高到就算你放入
14:32
a replicating program
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一个复制程序
14:34
that would otherwise happily grow up
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能快乐的成长
14:36
to fill the entire world,
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并布满整个空间
14:38
if you drop it in, it gets mutated to death immediately.
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如果你放进去，立刻突变至死亡
14:42
So there is no life possible
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所以那样的突变率
14:44
at that type of mutation rate.
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任何生命无法存活
14:47
But then I'm going to slowly turn down the heat, so to speak,
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但是我降低了温度
14:51
and then there's this viability threshold
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到这个可行阈值
14:53
where now it would be possible
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这样有一个复制体
14:55
for a replicator to actually live.
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能够存活
14:57
And indeed, we're going to be dropping these guys
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我们把这些家伙放进
15:00
into that soup all the time.
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（原始）汤里
15:02
So let's see what that looks like.
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是什么样子呢
15:04
So first, nothing, nothing, nothing.
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开始的时候什么都没有
15:07
Too hot, too hot.
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太热了太热了
15:09
Now the viability threshold is reached,
369
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达到可行阈值之后
15:12
and the frequency distribution
370
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频度分布
15:14
has dramatically changed and, in fact, stabilizes.
371
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开始剧烈变化然后稳定下来
15:17
And now what I did there
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然后我就
15:19
is, I was being nasty, I just turned up the heat again and again.
373
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很邪恶地调高了温度
15:22
And of course, it reaches the viability threshold.
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当然到达了可行阈值
15:25
And I'm just showing this to you again because it's so nice.
375
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我再给你们看一遍因为这个太棒了
15:28
You hit the viability threshold.
376
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降到可行阈值
15:30
The distribution changes to "alive!"
377
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分布就变成“有生命的”
15:32
And then, once you hit the threshold
378
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升高到可行阈值
15:35
where the mutation rate is so high
379
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突变率太高了
15:37
that you cannot self-reproduce,
380
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就无法自我繁殖
15:39
you cannot copy the information
381
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不能将信息
15:42
forward to your offspring
382
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没有错误地
15:44
without making so many mistakes
383
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复制给后代
15:46
that your ability to replicate vanishes.
384
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3000
复制的能力就消失了
15:49
And then that signature is lost.
385
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然后生命指标消失了
15:52
What do we learn from that?
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就此我们学到什么？
15:54
Well, I think we learn a number of things from that.
387
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我觉得我们学到几点
15:58
One of them is,
388
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第一是
16:00
if we are able to think about life
389
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如果我们可以
16:03
in abstract terms --
390
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从抽象意义上认知生命－
16:05
and we're not talking about things like plants,
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我们不是在讨论植物
16:07
and we're not talking about amino acids,
392
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也不是氨基酸
16:09
and we're not talking about bacteria,
393
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或者细菌
16:11
but we think in terms of processes --
394
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而是一种过程——
16:13
then we could start to think about life,
395
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那么我们可以认为生命
16:16
not as something that is so special to Earth,
396
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不是地球特有的
16:18
but that, in fact, could exist anywhere.
397
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可能存在任何一个地方
16:21
Because it really only has to do
398
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因为它只是
16:23
with these concepts of information,
399
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与信息的概念有关
16:25
of storing information
400
970000
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与储存信息有关
16:27
within physical substrates --
401
972000
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通过物质性基板——
16:29
anything: bits, nucleic acids,
402
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任何东西：数位，核酸
16:31
anything that's an alphabet --
403
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任何类似字母表的东西——
16:33
and make sure that there's some process
404
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并确保存在某种程序
16:35
so that this information can be stored
405
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从而信息可以被长久保存
16:37
for much longer than you would expect
406
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比你预期的信息损坏的
16:39
the time scales for the deterioration of information.
407
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时间尺度还要长很多
16:43
And if you can do that,
408
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如果是这样
16:45
then you have life.
409
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那么就是生命
16:47
So the first thing that we learn
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所以头一件我们学到的
16:49
is that it is possible to define life
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就是生命可以被定义为
16:52
in terms of processes alone,
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一种过程本身
16:55
without referring at all
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而不需要借助
16:57
to the type of things that we hold dear,
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其他我们珍视的东西
16:59
as far as the type of life on Earth is.
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比如地球上的生命形式
17:02
And that in a sense removes us again,
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这个结论再一次
17:05
like all of our scientific discoveries, or many of them --
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就像其他所有科学发现，或者很多科学发现－
17:08
it's this continuous dethroning of man --
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告诉人们－
17:10
of how we think we're special because we're alive.
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我们的存在并不是什么独特的事
17:13
Well we can make life. We can make life in the computer.
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我们可以创造生命，可以在电脑里创造生命
17:16
Granted, it's limited,
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当然这个有限
17:18
but we have learned what it takes
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但是我们据此可以知道
17:21
in order to actually construct it.
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构建生命的要素
17:23
And once we have that,
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一旦我们有这些要素
17:26
then it is not such a difficult task anymore
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那么创造生命不是什么难事
17:29
to say, if we understand the fundamental processes
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如果我们掌握了最基本的
17:33
that do not refer to any particular substrate,
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不借助于任何特殊基板的过程的话
17:36
then we can go out
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我们就能走出去
17:38
and try other worlds,
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探寻其他世界
17:40
figure out what kind of chemical alphabets might there be,
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了解那里有什么样的化学字母表
17:44
figure enough about the normal chemistry,
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了解一般的化学物质
17:46
the geochemistry of the planet,
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和那个星球的地理化学
17:49
so that we know what this distribution would look like
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那样我们就知道没有生命的
17:51
in the absence of life,
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分布是什么样子
17:53
and then look for large deviations from this --
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从而以此寻找更大的偏差－
17:56
this thing sticking out, which says,
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这个突起意味着
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"This chemical really shouldn't be there."
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“这个化学物质不应该在这儿”
18:01
Now we don't know that there's life then,
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现在我们还不知道那里有没有生命
18:03
but we could say,
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但是我们可以说
18:05
"Well at least I'm going to have to take a look very precisely at this chemical
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“至少我会精确地研究一下这个化学物质
18:08
and see where it comes from."
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看看哪里来的”
18:10
And that might be our chance
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这也许就是
18:12
of actually discovering life
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当我们无法看到生命
18:14
when we cannot visibly see it.
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但真正发现生命的机会
18:16
And so that's really the only take-home message
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这是我唯一的可以让你
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that I have for you.
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带回家的信息
18:21
Life can be less mysterious
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生命并不一定像
18:23
than we make it out to be
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我们以为的那样神秘
18:25
when we try to think about how it would be on other planets.
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如果我们知道其他星球上也存在的话
18:29
And if we remove the mystery of life,
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如果我们去掉生命的神秘感
18:32
then I think it is a little bit easier
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我像对于我们
18:35
for us to think about how we live,
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思考如何生活
18:37
and how perhaps we're not as special as we always think we are.
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和我们并不特殊来说会更容易
18:40
And I'm going to leave you with that.
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这就是我要讲的
18:42
And thank you very much.
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非常感谢
18:44
(Applause)
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（掌声）
ABOUT THE SPEAKER
Christoph Adami - Artificial life researcherChristoph Adami works on the nature of life and evolution, trying to define life in a way that is as free as possible from our preconceptions.
Why you should listen
Christoph Adami researches the nature of living systems, using 'artificial life' -- small, self-replicating computer programs. His main research focus is Darwinian evolution, which he studies at different levels of organization (from simple molecules to brains). He has pioneered theapplication of methods from information theory to the study of evolution, and designed the "Avida" system that launched the use of digital life as a tool for investigating basic questions in evolutionary biology.
He is Professor of Applied Life Sciences at the Keck Graduate Institute in Claremont, CA, and a Visiting Professor at the BEACON Center for the Study of Evolution in Action at Michigan State University. He obtained his PhD in theoretical physics from the State University of New York at Stony Brook.
Christoph Adami | Speaker | TED.com