Henry Lin: What we can learn from galaxies far, far away

翻译人员: Xuwen Zhu 校对人员: Bighead Ge

Here are some images of clusters of galaxies.

这是一些星团的照片

They're exactly what they sound like.

正如听上去一样

They are these huge collections of galaxies,

它们是一堆星系

bound together by their mutual gravity.

由于互相的引力而吸引在一起

So most of the points that you see on the screen

你在屏幕上看到的大部分点

are not individual stars,

不是单独的恒星

but collections of stars, or galaxies.

而是一系列恒星，或者称为星系

Now, by showing you some of these images,

现在通过展示这些图片

I hope that you will quickly see that

希望你已经看到

galaxy clusters are these beautiful objects,

星团是很美丽的东西

but more than that,

都不止于此

I think galaxy clusters are mysterious,

我认为星团是神秘的

they are surprising,

它们让人惊奇

and they're useful.

而且它们很有用

Useful as the universe's most massive laboratories.

作为宇宙里最大的实验室，它们很有用

And as laboratories, to describe galaxy clusters

就像描述实验室一样，要描述星团

is to describe the experiments

就要去描述你能够通过它们

that you can do with them.

做的实验

And I think there are four major types,

我认为那包括四种主要类型

and the first type that I want to describe

我想描述的第一类

is probing the very big.

是去探测“极大”。

So, how big?

那么，是多大？

Well, here is an image of a particular galaxy cluster.

这里是某个星团的一张照片

It is so massive that the light passing through it

它的质量非常大，以至于光在经过的时候

is being bent, it's being distorted

由于其引力的作用

by the extreme gravity of this cluster.

而变弯了

And, in fact, if you look very carefully

事实上，如果你仔细看

you'll be able to see rings around this cluster.

能够看到这个星团周围的光环

Now, to give you a number,

具体到数字

this particular galaxy cluster

这个星团的质量

has a mass of over one million billion suns.

有超过10的15次方个太阳那么大

It's just mind-boggling how massive these systems can get.

这些系统质量之巨大简直让人瞠目结舌

But more than their mass,

但除了巨大的质量之外

they have this additional feature.

他们还有其他特殊之处

They are essentially isolated systems,

它们基本上可以算是孤立的系统

so if we like, we can think of them

如果愿意的话，我们可以将它们

as a scaled-down version of the entire universe.

想象为整个宇宙的缩小版本

And many of the questions that we might have

我们关于宇宙在宏观上

about the universe at large scales,

有很多问题

such as, how does gravity work?

比如，引力是怎么起作用的？

might be answered by studying these systems.

这些问题可能可以通过研究这些系统来解决

So that was very big.

所以这就是“非常大”

The second things is very hot.

第二个特点是“非常热”

Okay, if I take an image of a galaxy cluster,

如果我拿出一幅星团的照片

and I subtract away all of the starlight,

去掉其中所有的星光

what I'm left with is this big, blue blob.

留下的是这个巨大的蓝色的一团

This is in false color.

这个颜色不是真的

It's actually X-ray light that we're seeing.

事实上这是X光

And the question is, if it's not galaxies,

问题是，如果不是这些星系

what is emitting this light?

那么是什么在发出这X光呢

The answer is hot gas,

答案是高温气体

million-degree gas --

一百万度的气体

in fact, it's plasma.

事实上是等离子

And the reason why it's so hot

温度如此之高的原因

goes back to the previous slide.

要回到前一张幻灯片

The extreme gravity of these systems

这些系统的超强引力

is accelerating particles of gas to great speeds,

将气体粒子加速到非常高的速度

and great speeds means great temperatures.

而高速则意味着高温

So this is the main idea,

这是主要的想法

but science is a rough draft.

但是里面的科学还不太明晰

There are many basic properties about this plasma

关于等离子气体，还有很多基本性质的问题

that still confuse us,

仍让我们困扰

still puzzle us,

仍然是谜团

and still push our understanding

但它正在推进我们对超高温物理

of the physics of the very hot.

的理解

Third thing: probing the very small.

第三个问题是：研究“极小”

Now, to explain this, I need to tell you

为了解释这个，我要说一件

a very disturbing fact.

很让人困扰的事实

Most of the universe's matter

宇宙的大部分物质

is not made up of atoms.

不是由原子构成

You were lied to.

你们以前被骗了

Most of it is made up of something very, very mysterious,

宇宙大部分是一种非常神秘的物质

which we call dark matter.

我们称为暗物质

Dark matter is something that doesn't like to interact very much,

暗物质不太与周围发生作用

except through gravity,

除了通过引力

and of course we would like to learn more about it.

理所当然的我们希望对其了解更多

If you're a particle physicist,

如果你是粒子物理学家

you want to know what happens when we smash things together.

你会想知道当我们撞击物体的时候发生什么

And dark matter is no exception.

暗物质也不例外

Well, how do we do this?

那么，我们怎么做呢

To answer that question,

为了回答这个问题

I'm going to have to ask another one,

我要问另一个问题

which is, what happens when galaxy clusters collide?

那就是，当星团碰撞的时候会发生什么？

Here is an image.

这是一张照片

Since galaxy clusters are representative

因为星团可以看做

slices of the universe, scaled-down versions.

是宇宙的缩小版

They are mostly made up of dark matter,

它们也是大部分由暗物质构成

and that's what you see in this bluish purple.

这就是你看到的偏蓝的紫色

The red represents the hot gas,

红色代表高温气体

and, of course, you can see many galaxies.

当然，你可以看到很多星系

What's happened is a particle accelerator

发生的事情就是一个非常巨大版本的

at a huge, huge scale.

粒子加速器

And this is very important,

这很重要

because what it means is that very, very small

因为这意味着，在实验室里

effects that might be difficult to detect in the lab,

某些因为太小而很难检测到的效果

might be compounded and compounded

可能因为不断的叠加

into something that we could possibly observe in nature.

而让我们在自然界观测到

So, it's very funny.

这很好玩

The reason why galaxy clusters

为什么星团可以

can teach us about dark matter,

教我们暗物质的知识

the reason why galaxy clusters

为什么它们

can teach us about the physics of the very small,

可以教我们关于“极小”的物理

is precisely because they are so very big.

其原因就是因为它们太大了

Fourth thing: the physics of the very strange.

第四个问题：关于“非常奇怪”的物理学

Certainly what I've said so far is crazy.

我刚才所说的已经很疯狂了

Okay, if there's anything stranger

但是，如果有比那些更疯狂的

I think it has to be dark energy.

我认为就是暗能量了

If I throw a ball into the air,

如果我把一个球扔向空中

I expect it to go up.

我预计它将上升

What I don't expect is that it go up

而我不会预计它

at an ever-increasing rate.

以越来越快的速度上升

Similarly, cosmologists understand why

同样的，宇宙学家理解

the universe is expanding.

为什么宇宙在膨胀

They don't understand why it's expanding

他们不理解的是，为什么宇宙

at an ever-increasing rate.

膨胀的速度越来越快

They give the cause of this

他们为加速膨胀的原因

accelerated expansion a name,

取了个名字

and they call it dark energy.

叫做暗能量

And, again, we want to learn more about it.

同样，我们希望对它了解更多

So, one particular question that we have is,

其中一个问题是

how does dark energy affect the universe

暗能量是如何

at the largest scales?

在极大的尺度上影响宇宙的？

Depending on how strong it is,

取决于能量的强弱

maybe structure forms faster or slower.

或许结构的形成会有快有慢

Well, the problem with the large-scale structure

但是对于宇宙的大尺度结构

of the universe is that it's horribly complicated.

问题是它复杂得可怕

Here is a computer simulation.

这是计算机模拟

And we need a way to simplify it.

我们需要简化它的方法

Well, I like to think about this using an analogy.

我会用一个类比来理解

If I want to understand the sinking of the Titanic,

如果我想了解泰坦尼克号的沉没

the most important thing to do

最重要的事情

is not to model the little positions

不是去模拟每一片断裂的小碎片

of every single little piece of the boat that broke off.

的每一个位置

The most important thing to do is

最重要的是

to track the two biggest parts.

抓住断裂的两半船体的位置

Similarly, I can learn a lot about the universe

同样，我可以通过追踪宇宙的

at the largest scales

最大的部件

by tracking its biggest pieces

来学到宇宙大尺度的很多信息

and those biggest pieces are clusters of galaxies.

而这最大的部件就是星团

So, as I come to a close,

现在我即将结尾

you might feel slightly cheated.

你可能觉得有点受骗上当

I mean, I began by talking about

我的意思是，刚开始我说

how galaxy clusters are useful,

星团非常有用

and I've given some reasons,

我也给了一些理由

but what is their use really?

但是他们真正的用处在哪里？

Well, to answer this,

为了回答这个

I want to give you a quote by Henry Ford

我将引用亨利·福特的一句话

when he was asked about cars.

当他被问到汽车时

He had this to say:

他说

"If I had asked people what they wanted,

“如果我之前问人们他们想要什么

they would have said faster horses."

他们只会说更快的马。”

Today, we as a society are faced

我们社会在现今

with many, many difficult problems.

面临很多很困难的问题

And the solutions to these problems are not obvious.

这些问题的解决之道并不明显

They are not faster horses.

解决之道不会是更快的马

They will require an enormous amount of

要解决问题，要求有非常多的

scientific ingenuity.

科学才能

So, yes, we need to focus,

是的，我们需要集中注意力

yes, we need to concentrate,

我们需要专心

but we also need to remember that

但我们也要记得

innovation, ingenuity, inspiration --

创造力、新颖的主意、灵感

these things come

这些是在我们开阔眼界时

when we broaden our field of vision

产生的

when we step back

当我们退后一步

when we zoom out.

当我们把画面拉远

And I can't think of a better way to do this than

我想不出更好的办法做这件事

by studying the universe around us. Thanks.

除了研究我们头顶的宇宙。谢谢。

(Applause)

（掌声）