评论
打印
1.3 billion years ago, in a distant, distant galaxy, two black holes locked into a spiral,
13亿年前，在一个无比遥远的星系，两个黑洞陷入了一个漩涡之中，
falling inexorably towards each other and collided, converting three Suns' worth of stuff into pure energy in a tenth of a second.
以不可阻挡之势冲向彼此，然后相撞，由此将等同于三个太阳的物质在十分之一秒内转化成了纯能量。
For that brief moment in time, the glow was brighter than all the stars in all the galaxies in all of the known Universe. It was a very big bang.
在那短暂的一瞬间，碰撞产生的光芒令已知宇宙中所有星系中的所有恒星都黯然失色。那是一个名副其实的大爆炸。
But they didn't release their energy in light. I mean, you know, they're black holes.
然而它们并没有以光的形式释放能量。因为它们是黑洞。
All that energy was pumped into the fabric of space and time itself, making the Universe explode in gravitational waves.
所有产生的能量都被注入时间和空间本身，使宇宙以引力波的形式延展。
Let me give you a sense of the timescale at work here. 1.3 billion years ago, Earth had just managed to evolve multicellular life.
让我来对所涉及的时间标度做一下说明。13亿年前，地球上刚出现了多细胞生物。
Since then, Earth has made and evolved corals, fish, plants, dinosaurs, people and even -- God save us -- the Internet.
在那之后，地球上的生物不断进化，珊瑚、鱼类、植物、恐龙、人类相继出现，当然，还有互联网。
And about 25 years ago, a particularly audacious set of people -- Rai Weiss at MIT, Kip Thorne and Ronald Drever at Caltech
大约25年前，一群极具冒险精神的人，麻省理工学院的瑞伊·维斯，以及加州理工学院的奇普·索恩和罗纳德·德雷弗，
decided that it would be really neat to build a giant laser detector with which to search for the gravitational waves from things like colliding black holes.
产生了一个他们认为非常了不起的想法：他们想要制造一台庞大的激光探测器，来搜寻由黑洞撞击等产生的引力波。
Now, most people thought they were nuts.
大多数人都觉得他们疯了。
But enough people realized that they were brilliant nuts that the US National Science Foundation decided to fund their crazy idea.
但也有很多人认为他们是了不起的疯子，所以美国国家科学基金会决定为他们这一疯狂的想法提供资金支持。
So after decades of development, construction and imagination and a breathtaking amount of hard work, they built their detector, called LIGO:
由此，经历了这几十年的发展，通过不断的建设和构想，以及惊人数量的辛勤工作，他们最终建成了这台名为LIGO的探测器：
The Laser Interferometer Gravitational-Wave Observatory.
全称叫做“激光干涉引力波观测台”。
For the last several years, LIGO's been undergoing a huge expansion in its accuracy, a tremendous improvement in its detection ability.
在过去的几年中，LIGO的准确性得到了巨大的提升，其探测能力也有了惊人的进步。
It's now called Advanced LIGO as a result.
所以现在它可以被称为“高端LIGO”。
In early September of 2015, LIGO turned on for a final test run while they sorted out a few lingering details.
2015年9月初，LIGO进行了最后一次试运行，辨识出了少量滞留的细节。
And on September 14 of 2015, just days after the detector had gone live,
随后，在2015年9月14日，即探测器正式运行数天后，
the gravitational waves from those colliding black holes passed through the Earth.
由黑洞撞击所产生的引力波经过了地球。
And they passed through you and me. And they passed through the detector.
它经过了我们每一个人。它也经过了那台探测器。
There's two moments in my life more emotionally intense than that. One is the birth of my daughter.
在我生命中只有两个时刻给予过我比这更为强烈的情感冲击。
The other is when I had to say goodbye to my father when he was terminally ill.
一个是我女儿出生的时候。另一个是我父亲病逝前我与他告别的时候。
You know, it was the payoff of my career, basically. Everything I'd been working on -- it's no longer science fiction!
可以说我从事这项事业就是为了这一刻，我为其付出努力的事情都不再是科幻小说了！
So that's my very good friend and collaborator, Scott Hughes, a theoretical physicist at MIT,
这是我的好友兼合作伙伴，斯科特·休斯，麻省理工学院理论物理学家，
who has been studying gravitational waves from black holes and the signals that they could impart on observatories like LIGO, for the past 23 years.
他研究产生于黑洞的引力波以及其传递给像LIGO这样的观测台的信号已经有23年之久。
So let me take a moment to tell you what I mean by a gravitational wave.
现在让我来简单介绍一下什么是引力波。
A gravitational wave is a ripple in the shape of space and time.
引力波是以时间和空间的形式产生的波动。
As the wave passes by, it stretches space and everything in it in one direction, and compresses it in the other.
当引力波通过时，它将空间及其中的所有事物向同一方向拉伸，同时将其在另一方向上压缩。
This has led to countless instructors of general relativity doing a really silly dance to demonstrate in their classes on general relativity.
这使得许多广义相对论教授在课堂上说明广义相对论时都跳起了滑稽的舞蹈，
"It stretches and expands, it stretches and expands."
“拉伸再扩展，拉伸再扩展。”
So the trouble with gravitational waves is that they're very weak; they're preposterously weak.
研究引力波的难点在于它们太微弱了；微弱得不合常理。
For example, the waves that hit us on September 14 -- and yes, every single one of you stretched and compressed under the action of that wave
就拿9月14日穿过我们的引力波为例，确实，在其作用下，我们每一个人都被拉伸和压缩了
when the waves hit, they stretched the average person by one part in 10 to the 21.
但这个过程中平均每个人仅被拉伸了10的21次方分之一。
That's a decimal place, 20 zeroes, and a one. That's why everyone thought the LIGO people were nuts.
也就是小数点后20个零，再加1个一。这就是为什么人们认为LIGO的研究者们都是疯子。
Even with a laser detector five kilometers long -- and that's already crazy
即使使用5千米长的激光探测器--这本身就很疯狂，
they would have to measure the length of those detectors to less than one thousandth of the radius of the nucleus of an atom. And that's preposterous.
他们还是需要以比原子核半径的千分之一还小的单位来测量那些探测器的长度。这真是超乎常人所能想象。
So towards the end of his classic text on gravity, LIGO co-founder Kip Thorne described the hunt for gravitational waves as follows:
在其关于万有引力的经典著作的末尾，LIGO的联合发明人奇普·索恩对引力波的探索进行了如下描述，
He said, "The technical difficulties to be surmounted in constructing such detectors are enormous.
他说：“要建成这样的探测器，需要克服巨大的技术难题。
But physicists are ingenious, and with the support of a broad lay public, all obstacles will surely be overcome."
但是，物理学家都是天才，再加上公众的广泛支持，所有的难关都会被攻克。”
Thorne published that in 1973, 42 years before he succeeded.
这本著作出版于1973年，42年后，他才获得了成功。
Now, coming back to LIGO, Scott likes to say that LIGO acts like an ear more than it does like an eye. I want to explain what that means.
让我们回到LIGO的话题上来，斯科特总是说，LIGO的运作方式更像是耳朵而非眼睛。让我来解释一下这句话的意思。
Visible light has a wavelength, a size, that's much smaller than the things around you, the features on people's faces, the size of your cell phone.
可见光的波长比我们身边的事物都要短，比如人的五官，或是你们的手机。
And that's really useful, because it lets you make an image or a map of the things around you,
这样的波长非常有用处，因为它令人们获得周围事物的直观影像。
by looking at the light coming from different spots in the scene about you.
借助来自身边场景的不同位置的光线。
Sound is different. Audible sound has a wavelength that can be up to 50 feet long.
声音就不同了。人们能听到的声音的波长可以达到50英尺。
And that makes it really difficult -- in fact, in practical purposes, impossible -- to make an image of something you really care about.
这使得声音很难--事实上，从实用意义来讲，根本不可能，去形成你所在意的事物的直观影像。
Your child's face. Instead, we use sound to listen for features like pitch and tone and rhythm and volume to infer a story behind the sounds.
比如你的孩子长什么样子。相反，我们通过声音来辨识音高、声调、节奏、音量等特征，以此来推断声音背后的故事。
That's Alice talking. That's Bob interrupting. Silly Bob.
爱丽丝正在讲话。鲍勃插话进来了。鲍勃真是不分场合。
So, the same is true of gravitational waves. We can't use them to make simple images of things out in the Universe.
引力波也有同样的作用。我们虽然不能通过引力波获得宇宙中事物的直观影像，
But by listening to changes in the amplitude and frequency of those waves, we can hear the story that those waves are telling.
但通过倾听引力波振幅和频率的变化，我们能够听出它们所传达的故事。
And at least for LIGO, the frequencies that it can hear are in the audio band.
至少LIGO接收到的波频在人们能听到的范围内。
So if we convert the wave patterns into pressure waves and air, into sound, we can literally hear the Universe speaking to us.
所以，如果我们把波形转化为压力波和空气波，即声音，我们就能确实地听到宇宙传达给我们的信息。
For example, listening to gravity, just in this way, can tell us a lot about the collision of two black holes,
比如，以这种形式倾听引力波，我们就能获得很多有关两个黑洞撞击的信息，
something my colleague Scott has spent an awful lot of time thinking about.
这也是我的同事斯科特花了大量时间探索的事情。
If the two black holes are non-spinning, you get a very simple chirp: whoop!
如果两个黑洞没有旋转，你听到的是“嗡”一声鸣响。
If the two bodies are spinning very rapidly, I have that same chirp, but with a modulation on top of it, so it kind of goes: whir, whir, whir!
如果这两个黑洞高速旋转，响声是相同的，但调制却发生了变化，听起来就像这样：嗡--嗡--嗡！
It's sort of the vocabulary of spin imprinted on this waveform.
可以说这就是旋转在波形图上留下的只言片语。
So on September 14, 2015, a date that's definitely going to live in my memory, LIGO heard this:
在2015年9月14日，一个我将永远铭记的日子，LIGO听到了这样的声音：
So if you know how to listen, that is the sound of --
懂得如何倾听它的人知道，这个声音来自--
two black holes, each of about 30 solar masses, that were whirling around at a rate comparable to what goes on in your blender.
两个质量均为太阳30倍左右的黑洞，以相当于搅拌机运转的速度旋转时所发出的声音。
It's worth pausing here to think about what that means.
我们有必要停下来好好想想这意味着什么。
Two black holes, the densest thing in the Universe, one with a mass of 29 Suns and one with a mass of 36 Suns,
两个黑洞，宇宙中密度最高的物体，其中一个的质量是太阳的29倍，另一个是太阳的36倍，
whirling around each other 100 times per second before they collide.
它们以每秒钟100次的速度绕着彼此旋转，然后相互碰撞。
Just imagine the power of that. It's fantastic. And we know it because we heard it.
想象一下其中的能量。简直不可思议。我们之所以知道这一切，是因为我们听到了它们。
That's the lasting importance of LIGO. It's an entirely new way to observe the Universe that we've never had before.
而这就是LIGO的长远价值所在。它为我们提供了一种前所未有的观察宇宙的途径。
It's a way that lets us hear the Universe and hear the invisible.
通过这一途径，我们可以倾听宇宙，倾听不可见的事物。
And there's a lot out there that we can't see -- in practice or even in principle.
在实践中甚至是理论上，宇宙中的许多事物都是不可见的。
So supernova, for example: I would love to know why very massive stars explode in supernovae.
举个例子，超新星--我非常想知道为什么恒星质量达到一定程度时就会发生超新星爆发。
They're very useful; we've learned a lot about the Universe from them.
这很有价值，它们帮助我们获得了许多有关宇宙的信息。
The problem is, all the interesting physics happens in the core,
问题是，所有有趣的物理现象都发生在内核，
and the core is hidden behind thousands of kilometers of iron and carbon and silicon.
而内核掩藏在数千公里厚的铁、碳、硅元素之下。
We'll never see through it, it's opaque to light. Gravitational waves go through iron as if it were glass -- totally transparent.
这些元素不透光，我们永远无法看穿它们。而引力波却能穿过铁；就像穿过完全透明的玻璃一样。
The Big Bang: I would love to be able to explore the first few moments of the Universe,
再举个例子，大爆炸。我很想研究宇宙初始的时刻发生的一切，
but we'll never see them, because the Big Bang itself is obscured by its own afterglow.
但是我们已经无法看到了，因为大爆炸本身已经被其发出的余辉所掩盖。
With gravitational waves, we should be able to see all the way back to the beginning.
利用引力波，我们有可能看到其最初的状态。
Perhaps most importantly, I'm positive that there are things out there that we've never seen that we may never be able to see
或许，最重要的是，我肯定宇宙中还有很多事物是我们见所未见的，或是永不可见的，
and that we haven't even imagined -- things that we'll only discover by listening.
甚至是我们无法想象的--我们只能通过倾听去发现这一切。
And in fact, even in that very first event, LIGO found things that we didn't expect.
事实上，在运行之初，LIGO就发现了我们意想不到的事物。
Here's my colleague and one of the key members of the LIGO collaboration, Matt Evans, my colleague at MIT, addressing exactly that:
下面的录音来自我的同事，一位LIGO合作研究的主要成员，麻省理工学院的马特·埃文斯，他提到的正是这一点：
The kinds of stars which produce the black holes that we observed here are the dinosaurs of the Universe.
我们现在观察到的这两个黑洞，它们源自的恒星可以说是宇宙中的恐龙。
They're these massive things that are old, from prehistoric times,
它们是来自于史前时代古老而巨大的存在，
and the black holes are kind of like the dinosaur bones with which we do this archeology.
而黑洞则像是恐龙的骨骼化石，我们通过它们进行考古研究。
So it lets us really get a whole nother angle on what's out there in the Universe and how the stars came to be,
这给了我们一个全新的视角，去思考宇宙中存在的事物，思考星体的形成过程，
and in the end, of course, how we came to be out of this whole mess.
当然，最终要去思考人类在宇宙混沌中的发展之道。
Our challenge now is to be as audacious as possible.
我们当下的挑战就是要更加大胆尝试。
Thanks to LIGO, we know how to build exquisite detectors that can listen to the Universe, to the rustle and the chirp of the cosmos.
LIGO让我们知道如何去建造精密的探测器，以此来倾听宇宙，倾听其中的低簌与鸣响。
Our job is to dream up and build new observatories -- a whole new generation of observatories -- on the ground, in space.
我们的工作是要大胆想象并建造新的观测台--在地球上和太空中建立全新一代的观测台。
I mean, what could be more glorious than listening to the Big Bang itself?
我是说，还有什么事能比倾听宇宙大爆炸更为美妙呢？
Our job now is to dream big. Dream with us. Thank you.
我们的工作就是创造伟大的梦想。跟我们一起梦想吧！谢谢。
