Gabriela González: How LIGO discovered gravitational waves (with English subtitles) | TED

翻译人员: Nancy Shen 校对人员: Echo Sun

A little over 100 years ago, in 1915,

在 1915 年，也就是 100 多年前，

Einstein published his theory of general relativity,

爱因斯坦发表了他的相对论理论，

which is sort of a strange name,

这个理论的名字虽然听起来很奇怪，

but it's a theory that explains gravity.

但是它解释了万有引力。

It states that mass -- all matter, the planets -- attracts mass,

该理论指出，所有物质（包括星球） 都会互相吸引,

not because of an instantaneous force, as Newton claimed,

这并不是由于牛顿所提出的瞬时力，

but because all matter -- all of us, all the planets --

而是因为所有的事物—— 包括我们人类以及所有的星球——

wrinkles the flexible fabric of space-time.

使富有弹性的时空结构出现了褶皱。

Space-time is this thing in which we live and that connects us all.

我们活在时空中， 时空联系了我们所有的人，

It's like when we lie down on a mattress and distort its contour.

这种感觉就像我们躺在床垫上， 使其发生了形变。

The masses move -- again, not according to Newton's laws,

再次重申，万物运动 不是依照牛顿的法则，

but because they see this space-time curvature

而是因为它们之间有时空曲率，

and follow the little curves,

它们按照这些平滑的曲线运动。

just like when our bedmate nestles up to us

就好像床垫轻微陷了下去，

because of the mattress curvature.

使枕边人向我们靠近了一样。

(Laughter)

（笑声）

A year later, in 1916,

一年以后的 1916 年，

Einstein derived from his theory

爱因斯坦从他的理论中得出：

that gravitational waves existed,

引力波是存在的，

and that these waves were produced when masses move,

当万物移动的时候就会产生引力波。

like, for example, when two stars revolve around one another

比如，当两颗恒星围着彼此旋转

and create folds in space-time which carry energy from the system,

并在时空中产生褶皱， 这些褶皱携带着来自系统的能量，

and the stars move toward each other.

这两颗恒星就会互相靠近。

However, he also estimated

不过，他也预计

that these effects were so minute,

这种作用力太微小，

that it would never be possible to measure them.

不大可能对其进行测量。

I'm going to tell you the story of how,

但我想告诉各位的是，

with the work of hundreds of scientists working in many countries

经过多个国家上百名科学家

over the course of many decades,

数十载的埋头钻研，

just recently, in 2015,

终于，在 2015 年，

we discovered those gravitational waves for the first time.

我们首次观测到了引力波。

It's a rather long story.

这是个漫长的故事，

It started 1.3 billion years ago.

一切从 13 亿年前开始。

A long, long time ago,

很久很久以前，

in a galaxy far, far away --

在一个非常非常遥远的星系——

(Laughter)

(笑声)

two black holes were revolving around one another --

两个黑洞相互围绕着对方转动，

"dancing the tango," I like to say.

用我自己的话说，就像在“跳探戈舞”一样。

It started slowly,

刚开始速度很慢，

but as they emitted gravitational waves,

但随着它们不断释放引力波，

they grew closer together, accelerating in speed,

开始加速接近对方，

until, when they were revolving at almost the speed of light,

直至彼此都以光速转动，

they fused into a single black hole

最终融合成一个黑洞，

that had 60 times the mass of the Sun,

它的质量是太阳的 60 倍，

but compressed into the space of 360 kilometers.

但却被压缩进了 只有 360 公里大小的空间，

That's the size of the state of Louisiana,

相当于我所居住的

where I live.

路易斯安那州的面积。

This incredible effect produced gravitational waves

这个奇妙的作用产生的引力波

that carried the news of this cosmic hug to the rest of the universe.

把黑洞融合的消息 传递到了宇宙的其他角落。

It took us a long time to figure out the effects of these gravitational waves,

我们花了很长时间才发现了引力波，

because the way we measure them is by looking for effects in distances.

因为我们必须找出距离的变化 才能测量引力波。

We want to measure longitudes, distances.

我们想要测量经度和距离。

When these gravitational waves passed by Earth,

当引力波在 2015 年

which was in 2015,

经过地球，

they produced changes in all distances --

它们改变了所有的距离——

the distances between all of you, the distances between you and me,

包括你们所有人， 以及你们和我之间的距离，

our heights --

还有我们的高度——

every one of us stretched and shrank a tiny bit.

我们每个人的尺寸 都缩放了一点点。

The prediction is that the effect is proportional to the distance.

科学家预测其变化与距离成正比。

But it's very small:

但这种变化很小：

even for distances much greater than my slight height,

即使是比我那微不足道的身高 变化大许多的距离，

the effect is infinitesimal.

其变化也是极微小的。

For example, the distance between the Earth and the Sun

假如地球和太阳之间的距离

changed by one atomic diameter.

仅发生了一个原子直径那么小的改变，

How can that be measured?

我们能够测量到这个变化吗？

How could we measure it?

应该怎样进行测量呢？

Fifty years ago,

50 年前，

some visionary physicists at Caltech and MIT --

加州理工学院和麻省理工学院的 一些有远见的物理学家——

Kip Thorne, Ron Drever, Rai Weiss --

基普·索恩（Kip Thorne）、罗纳德·德瑞福 （Ron Drever）和莱纳·魏斯（Rai Weiss）——

thought they could precisely measure distances

认为可以利用激光来测量

using lasers that measured distances between mirrors

相距几公里远的镜子间的距离，

kilometers apart.

从而精确地测量出引力波，

It took many years, a lot of work and many scientists

这个项目花费了许多年， 无数的科学家做了大量的工作，

to develop the technology and develop the ideas.

不断研发技术和细化想法。

And 20 years later,

然后二十年过去了，

almost 30 years ago,

大约在三十年前，

they started to build two gravitational wave detectors, two interferometers,

他们开始在美国建立两个 巨大的引力波探测器

in the United States.

和两个干涉仪。

Each one is four kilometers long;

每一台仪器都有 4000 米长，

one is in Livingston, Louisiana,

一台位于路易斯安那州利文斯顿

in the middle of a beautiful forest,

一片美丽的森林中，

and the other is in Hanford, Washington,

另一台位于华盛顿州汉福德的

in the middle of the desert.

一片沙漠之中。

The interferometers have lasers

干涉仪有激光发射器，

that travel from the center through four kilometers in-vacuum,

激光从仪器中心发射出去， 穿过 4000 米的真空，

are reflected in mirrors and then they return.

再被镜子反射回来。

We measure the difference in the distances

我们测量两臂之间

between this arm and this arm.

距离的差值。

These detectors are very, very, very sensitive;

这些探测器都非常非常灵敏，

they're the most precise instruments in the world.

是世界上最精确的仪器。

Why did we make two?

那么我们为什么要制造两台呢？

It's because the signals that we want to measure come from space,

这是因为我们要测量的信号来自太空，

but the mirrors are moving all the time,

但是镜子却总是在移动，

so in order to distinguish the gravitational wave effects --

所以为了区分引力波效应——

which are astrophysical effects and should show up on the two detectors --

这是天体物理效应， 应该会出现在两个探测器上——

we can distinguish them from the local effects,

我们可以把引力波 和局部效应区分开来，

which appear separately, either on one or the other.

并体现在其中一个探测仪上。

In September of 2015,

2015 年 9 月，

we were finishing installing the second-generation technology

我们在探测仪上

in the detectors,

完成了第二代技术的安装，

and we still weren't at the optimal sensitivity that we wanted --

但是我们仍未取得最佳的灵敏度——

we're still not, even now, two years later --

——即使是两年后的今天也没有——

but we wanted to gather data.

但是我们迫不及待地想要收集数据。

We didn't think we'd see anything,

我们不认为自己能够有什么发现，

but we were getting ready to start collecting a few months' worth of data.

但是我们已经准备好 收集相当于几个月的数据。

And then nature surprised us.

然后，大自然震惊了我们。

On September 14, 2015,

在 2015 年的 9 月 14 日，

we saw, in both detectors,

我们在两个探测器中

a gravitational wave.

都发现了一条引力波。

In both detectors, we saw a signal

在两个探测器中， 我们都检测到了一条信号，

with cycles that increased in amplitude and frequency

振幅和频率

and then go back down.

呈周期性增减。

And they were the same in both detectors.

两台探测器探测到的信号都是一样的。

They were gravitational waves.

它们就是引力波！

And not only that -- in decoding this type of wave,

而且不仅如此——在分析这种波形的同时，

we were able to deduce that they came from black holes

我们能够判断，它们来自于

fusing together to make one,

十亿年前几个黑洞

more than a billion years ago.

融合产生的黑洞。

And that was --

那真的是——

(Applause)

（掌声）

that was fantastic.

那真是非常奇妙。

At first, we couldn't believe it.

最初，我们都无法相信这个事实。

We didn't imagine this would happen until much later;

过了很久我们才回过神来。

it was a surprise for all of us.

对我们来说，这是一个惊喜。

It took us months to convince ourselves that it was true,

我们花费了数月的时间说服自己， 我们真的探测到了引力波，

because we didn't want to leave any room for error.

因为我们不想有任何地方出错。

But it was true, and to clear up any doubt

这的确是真的，而且为了确保

that the detectors really could measure these things,

探测器真的能够测量这些信号，

in December of that same year,

在同年的十二月，

we measured another gravitational wave,

我们又测量到了另一个引力波，

smaller than the first one.

比首次探测到的要小。

The first gravitational wave produced a difference in the distance

首次探测的引力波 在 4000 米的距离内产生了

of four-thousandths of a proton

相当于千分之四个

over four kilometers.

质子大小的差距。

Yes, the second detection was smaller,

是的，虽然第二次 探测信号比第一次要微弱，

but still very convincing by our standards.

但是以我们的标准， 这一结果仍然十分具有说服力。

Despite the fact that these are space-time waves and not sound waves,

尽管这实际上是 时空波而不是声波，

we like to put them into loudspeakers and listen to them.

我们依旧喜欢把它们 转换成声音信号，去聆听它们。

We call this "the music of the universe."

我们管它叫作“宇宙的旋律”。

I'd like you to listen to the first two notes of that music.

我想让大家听一听 这段旋律的前两个音符。

(Chirping sound)

（鸣声）

(Chirping sound)

（鸣声）

The second, shorter sound was the last fraction of a second

第二个较为短促的声音是

在两个黑洞融合的 最后一秒内产生的，

of the two black holes which,

in that fraction of a second, emitted vast amounts of energy --

在那一瞬间， 它们释放出了巨大的能量——

so much energy, it was like three Suns converting into energy,

其规模相当于三个太阳 全部转化成的能量，

following that famous formula,

遵循那道著名的方程：

E = mc2.

E = mc^2。

Remember that one?

还记得这个吗？

We love this music so much we actually dance to it.

我们太喜欢这段旋律了， 还伴着它跳了段舞。

I'm going to have you listen again.

我们再听一遍。

(Chirping sound)

（鸣声）

(Chirping sound)

（鸣声）

It's the music of the universe!

这就是宇宙的旋律！

(Applause)

（掌声）

People frequently ask me now:

人们现在经常问我：

"What can gravitational waves be used for?

“引力波究竟有什么用？

And now that you've discovered them, what else is there left to do?"

既然你们现在已经探测到了引力波， 下一步要做什么？”

What can gravitational waves be used for?

引力波可以被用来做什么呢？

When they asked Borges, "What is the purpose of poetry?"

当他们问博尔赫斯（Jorge Luis Borges， 阿根廷作家、诗人），“诗存在的意义是什么？”

he, in turn, answered,

他回答道：

"What's the purpose of dawn?

“绘画的意义是什么？

What's the purpose of caresses?

爱抚的意义是什么？

What's the purpose of the smell of coffee?"

咖啡香味的意义又是什么？”

He answered,

他还说：

"The purpose of poetry is pleasure; it's for emotion, it's for living."

“诗的意义是为了美好、 是为了感情、为了生活而存在的。”

And understanding the universe,

这一点与了解宇宙——

this human curiosity for knowing how everything works,

出于人类渴望了解 万物如何运作的好奇心，

is similar.

是相似的。

Since time immemorial, humanity -- all of us, everyone, as kids --

自古以来，人类—— 在我们每一个人还是孩子的时候——

when we look up at the sky for the first time and see the stars,

当我们第一次仰望星空， 看到那些星星的时候，

we wonder,

我们会好奇：

"What are stars?"

“星星是什么？”

That curiosity is what makes us human.

正是这种好奇造就了人类。

And that's what we do with science.

这也是我们研究科学的原因。

We like to say that gravitational waves now have a purpose,

我们认为，引力波的意义在于，

because we're opening up a new way to explore the universe.

我们打开了一条新的探索宇宙的通道。

Until now, we were able to see the light of the stars

在那以前，我们只能通过电磁波

via electromagnetic waves.

看到来自恒星的光芒。

Now we can listen to the sound of the universe,

而现在，我们却可以 听到来自宇宙的声音，

even of things that don't emit light, like gravitational waves.

甚至是那些不会发光的东西， 比如引力波。

(Applause)

（掌声）

Thank you.

谢谢大家！

(Applause)

（掌声）

But are they useful?

但是它们到底有什么用呢？

Can't we derive any technology from gravitational waves?

我们能借助引力波 发展一些新的科技吗？

Yes, probably.

是的，或许可以。

But it will probably take a lot of time.

但是这可能会花费更久的时间，

We've developed the technology to detect them,

我们已经开发了探测引力波的技术，

but in terms of the waves themselves,

但是对于引力波本身，

maybe we'll discover 100 years from now that they are useful.

也许我们 100 年后 才会发现它们的真正用途。

But it takes a lot of time to derive technology from science,

但是把科学转变成技术 会花费很久的时间，

and that's not why we do it.

这也并不是我们做这些事的原因。

All technology is derived from science,

所有的科技都是 从科学中发展出来的，

but we practice science for the enjoyment.

但是我们从事科学是为了享受。

What's left to do?

那剩下还有什么要做的？

A lot.

还有很多。

A lot; this is only the beginning.

太多了，这还只是一个开始。

As we make the detectors more and more sensitive --

随着我们把探测器做得越来越精确——

and we have lots of work to do there --

我们仍有很多的工作需要做——

not only are we going to see more black holes

我们不仅会发现更多的黑洞，

and be able to catalog how many there are, where they are

并且能够去分类总结—— 究竟有多少，在哪里，

and how big they are,

尺寸究竟有多大；

we'll also be able to see other objects.

我们还将能观测到其它的物质：

We'll see neutron stars fuse and turn into black holes.

我们会观测到 中子星融合并转化为黑洞

We'll see a black holes being born.

以及黑洞的诞生过程；

We'll be able to see rotating stars in our galaxy

银河系里旋转的恒星

produce sinusoidal waves.

产生的正弦波；

We'll be able to see explosions of supernovas in our galaxy.

银河系中超新星的爆炸。

We'll be seeing a whole spectrum of new sources.

我们还将会看到新事物的完整波谱。

We like to say

我们认为，

that we've added a new sense to the human body:

我们为人类增加了一种新的感官：

now, in addition to seeing,

除了视觉，

we're able to hear.

我们还能够去聆听。

This is a revolution in astronomy,

这是天文学的一次革命，

like when Galileo invented the telescope.

就像伽利略发明了天文望远镜一样。

It's like when they added sound to silent movies.

就像人们把声音 加入了无声电影中一样。

This is just the beginning.

这一切仅仅只是个开始。

We like to think

我们也认为，

that the road to science is very long -- very fun, but very long --

通向科学的道路仍旧十分漫长—— 尽管非常有趣，但也很长——

and that we, this large, international community of scientists,

同时，我们这个庞大的、 由来自众多国家的科学家组成的

working from many countries, together as a team,

国际组织，会齐心协力

are helping to build that road;

帮助建设那条道路：

that we're shedding light -- sometimes encountering detours --

我们正在照亮前路—— 尽管有时会遇到艰难险阻——

and building, perhaps,

并且建设一条可能是

a highway to the universe.

通向宇宙的高速公路。

Thank you.

谢谢大家！

(Applause)

（掌声）