1.How do you observe something you can’t see?
如何观察那些你看不见的东西？
2.This is the basic question of somebody who’s interested in finding and studying black holes.
对于有兴趣寻找和研究黑洞的人来说， 这是个根本问题。
3.Because black holes are objects whose pull of gravity is so intense that nothing can escape it, not even light, so you can’t see it directly.
因为黑洞的引力极为强大， 任何物体 包括光线，都不能逃脱。 所以你不能直接看到它。
4.So, my story today about black holes is about one particular black hole.
我今天要讲的黑洞 是关于一种特别的黑洞。
5.I’m interested in finding whether or not there is a really massive, what we like to call “supermassive” black hole at the center of our galaxy.
我的兴趣在于是否 存在一个特别巨大，我们称之为“超大质量黑洞” 的黑洞存在银河系中心。
6.And the reason this is interesting is that it gives us an opportunity to prove whether or not these exotic objects really exist.
感兴趣的原因是 这将给我们一个机会去证明 是否这些奇特的物体是否真的存在。
7.And second, it gives us the opportunity to understand how these supermassive black holes interact with their environment, and to understand how they affect the formation and evolution
其次，这给我们一个机会 去了解这些特大质量黑洞是如何 与他们的环境进行互动， 以及它们是如何影响到
8.of the galaxies which they reside in.
所处宇宙的形成和演化
9.So, to begin with, we need to understand what a black hole is so we can understand the proof of a black hole.
言归正传， 首先，我们必须理解黑洞是什么， 这样我们才能理解黑洞存在的证据。
10.So, what is a black hole?
那么，黑洞是什么？
11.Well, in many ways a black hole is an incredibly simple object, because there are only three characteristics that you can describe:
从很多方面来说，黑洞是个简单到不可思议的物体， 它只有三个特征可以测量：
12.the mass, the spin, and the charge.
质量 角动量和电荷。
13.And I’m going to only talk about the mass.
而我将只讨论质量。
14.So, in that sense, it’s a very simple object.
从这个意义上来说，它是非常简单的物体。
15.But in another sense, it’s an incredibly complicated object that we need relatively exotic physics to describe, and in some sense represents the breakdown of our physical understanding
但是，换个角度，它又是极其复杂的， 以至于我们需要相对来说比较奇特的物理学来描述， 在某种程度上还标识着我们对于宇宙的的物理认知的崩溃。
16.of the universe.
（）
17.But today, the way I want you to understand a black hole, for the proof of a black hole, is to think of it as an object whose mass is confined to zero volume.
如今，为了让你了解黑洞 了解黑洞存在的证据， 是把它看作一个 质量为零的物体
18.So, despite the fact that I’m going to talk to you about an object that’s supermassive, and I’m going to get to what that really means in a moment,
尽管我将和你们谈谈关于 超质量的物体 而对于这个物体，我将在后面进行阐述
19.it has no finite size.
它没有大小。
20.So, this is a little tricky.
这有点棘手。
21.But fortunately there is a finite size that you can see, and that’s known as the Schwarzschild radius.
但幸运的是你可以看到有限的大小， 这被称为史瓦西半径
22.And that’s named after the guy who recognized why it was such an important radius.
它命名于史瓦西 他发现了为什么这个半径是如此重要
23.This is a virtual radius, not reality; the black hole has no size.
这是一个虚拟的半径，而不是真实的；黑洞没有大小
24.So why is it so important?
那么，为什么这很重要呢？
25.It’s important because it tells us that any object can become a black hole.
它重要是因为它告诉我们 任何物体都可以成为黑洞
26.That means you, your neighbor, your cellphone, the auditorium can become a black hole if you can figure out how to compress it down
这意味着你的邻居，你的手机， 还有礼堂都能成为黑洞 如果你能弄明白
27.to the size of the Schwarzschild radius.
如何把它压缩至史瓦西半径大小。
28.At that point, what’s going to happen?
在这一点上，会发生什么？
29.At that point gravity wins.
在这一点上，引力获胜。
30.Gravity wins over all other known forces.
引力胜过其他所有已知力量
31.And the object is forced to continue to collapse to an infinitely small object.
物体被迫继续坍塌 成为一个奇点。
32.And then it’s a black hole.
这就是黑洞。
33.So, if I were to compress the Earth down to the size of a sugar cube, it would become a black hole, because the size of a sugar cube is its Schwarzschild radius.
如果把地球压缩至一块方糖大小， 地球就会成为一个黑洞 因为方糖的大小是它的史瓦西半径。
34.Now, the key here is to figure out what that Schwarzschild radius is.
现在，关键是要弄清楚什么是史瓦西半径。
35.And it turns out that it’s actually pretty simple to figure out.
事实证明，这很容易算出来
36.It depends only on the mass of the object.
它只依赖于物体的质量。
37.Bigger objects have bigger Schwarzschild radii.
更大的物体有更大的是史瓦西半径。
38.Smaller objects have smaller Schwarzschild radii.
更小的物体有更小的史瓦西半径。
39.So, if I were to take the sun and compress it down to the scale of the University of Oxford, it would become a black hole.
因此，如果我把太阳 压缩至英国牛津大学的大小， 太阳会成为一个黑洞。
40.So, now we know what a Schwarzschild radius is.
现在，我们知道了什么是史瓦希半径。
41.And it’s actually quite a useful concept, because it tells us not only when a black hole will form, But it also gives us the key elements for the proof of a black hole.
它实际上是一个相当有用的概念， 因为它不仅告诉我们 黑洞何时形成， 同时还带给我们黑洞存在证据的关键要素。
42.I only need two things.
我只需要两件东西。
43.I need to understand the mass of the object I’m claiming is a black hole, and what its Schwarzschild radius is.
我需要了解物体的质量 我自称是一个黑洞， 以及其史瓦西半径。
44.And since the mass determines the Schwarzschild radius, there is actually only one thing I really need to know.
由于质量决定史瓦西半径， 实际上只有一件事我需要知道。
45.So, my job in convincing you that there is a black hole, is to show that there is some object that’s confined to within its Schwarzschild radius.
因此，我的工作是说服你 那有一个黑洞， 表明有一些物体 仅限于其史瓦西半径·
46.And your job today is to be skeptical.
而你要做的是对此表示怀疑。
47.Okay, so, I’m going to talk about no ordinary black hole; I’m going to talk about supermassive black holes.
好了，我要谈的不是常规黑洞； 我要谈论的是超大质量黑洞。
48.So, I wanted to say a few words about what an ordinary black hole is, as if there could be such a thing as an ordinary black hole.
因此，我要说常规黑洞是什么 好像有这样一个可以作为常规黑洞的东西。
49.An ordinary black hole is thought to be the end state of a really massive star’s life.
一个常规黑洞可以被看作是 大质量恒星生命的晚期。
50.So, if a star starts its life off with much more mass than the mass of the Sun, it’s going to end its life by exploding and leaving behind these beautiful supernova remnants that we see here.
因此，当一个恒星消亡 而这个恒星的质量远大于太阳 它将以爆炸结束生命 我们将会看到留下的超新星遗骸
51.And inside that supernova remnant is going to be a little black hole that has a mass roughly three times the mass of the Sun.
在超新星遗骸的内部 形成一个小型黑洞 质量大概是太阳的3倍。
52.On an astronomical scale that’s a very small black hole.
从天文学的角度来看 这是一个非常小的黑洞
53.Now, what I want to talk about are the supermassive black holes.
现在，我想谈谈超大质量黑洞。
54.And the supermassive black holes are thought to reside at the center of galaxies.
超大质量黑洞被认为位于星系中心。
55.And this beautiful picture taken with the Hubble Space Telescope shows you that galaxies come in all shapes and sizes.
这幅美丽的图片是哈勃太空望远镜拍摄的 展示了星系的所有形状和大小。
56.There are big ones. There are little ones.
有大的，有小的。
57.Almost every object in that picture there is a galaxy.
几乎图片上的每一个物体都是一个星系。
58.And there is a very nice spiral up in the upper left.
有一个非常漂亮的螺旋臂在左上角。
59.And there are a hundred billion stars in that galaxy, just to give you a sense of scale.
有100亿颗恒星在那个星系中， 仅仅给你一种规模感。
60.And all the light that we see from a typical galaxy, which is the kind of galaxies that we’re seeing here, comes from the light from the stars.
我们从一个典型的星系中看到的所有光线， 是我们在这儿看到的星系中的一种， 来自恒星的光线。
61.So, we see the galaxy because of the star light.
我们看见星系是因为恒星的光。
62.Now, there are a few relatively exotic galaxies.
有一些比较奇特的星系
63.I like to call these the prima donna of the galaxy world, because they are kind of show offs.
我喜欢称这些星系为女主角， 因为它们特别愿意展示自己
64.And we call them active galactic nuclei.
我们称之为活跃星系核心。
65.And we call them that because their nucleus, or their center, are very active.
我们之所以这样称呼是因为它们的核心， 或者它们的中心，非常活跃。
66.So, at the center there, that’s actually where most of the starlight comes out from.
在中心位置， 大部分星光是从那发出的。
67.And yet, what we actually see is light that can’t be explained by the starlight.
然而，事实上我们看到的是 无法用星光来解释的光
68.It’s way more energetic.
它比星光更有活力。
69.In fact, in a few examples it’s like the ones that we’re seeing here.
事实上，下面的例子中跟我们现在看的这些有些相似。
70.There are also jets emanating out from the center.
也是从中心喷射出。
71.Again, a source of energy that’s very difficult to explain if you just think that galaxies are composed of stars.
如果你仅仅认为星系是由恒星组成的 那这股能量的来源就很难解释了。
72.So, what people have thought is that perhaps there are supermassive black holes which matter is falling on to.
人们认为 也许有超大质量黑洞 所以物质被吸引过去。
73.So, you can’t see the black hole itself, but you can convert the gravitational energy of the black hole into the light we see.
你不能看见黑洞本身， 但是你能将黑洞的引力 转换为我们能见的光。
74.So, there is the thought that maybe supermassive black holes exist at the center of galaxies.
因此，有一种想法就是 也许超大质量黑洞存在于星系的中心。
75.But it’s a kind of indirect argument.
但这仅是一种间接论据。
76.Nonetheless, it’s given rise to the notion that maybe it’s not just these prima donnas that have these supermassive black holes, but rather all galaxies might harbor these
尽管如此，这却带来了一种概念 也许不仅是这些主角 有超大质量黑洞 而是所有的星系中心
77.supermassive black holes at their centers.
都有可能藏匿超大质量黑洞
78.And if that’s the case — And this is an example of a normal galaxy; what we see is the star light.
如果是这种情况——这是一个常规星系的例子； 我们看到的是星光。
79.And if there is a supermassive black hole, what we need to assume is that it’s a black hole on a diet.
如果有超大质量黑洞， 我们需要假设的是它是一个正在节食的黑洞。
80.Because that is the way to suppress the energetic phenomena that we see in active galactic nuclei.
因为这是一种我们所见到的压制现象 在活跃星系的核心
81.If we’re going to look for these stealth black holes at the center of galaxies, the best place to look is in our own galaxy, our Milky Way.
如果我们要在星系中心找寻 这些隐藏的黑洞， 最好的地方就是我们所在的星系，银河系。
82.And this is a wide field picture taken of the center of the Milky Way.
这是一张银河系中心的 大范围图片
83.And what we see is a line of stars.
我们看到的是线状的恒星系。
84.And that is because we live in a galaxy which is a flattened, disk-like structure.
因为我们所在的星系 是一个扁平的，盘状结构的星系。
85.And we live in the middle of it, so when we look towards the center, we see this plane which defines the plane of the galaxy, or line that defines the plane of the galaxy.
而且我们居住在中央，因此当我们看向中心， 我们把这个平面看成是星系的平面， 或者把这条线看成是星系的平面
86.Now, the advantage of studying our own galaxy is it’s simply the closest example of the center of a galaxy that we’re ever going to have, because the next closest galaxy
研究我们自己的星系的优势是 在我们接触过的星系中心的实体中 这是距离我们最近的星系
87.is 100 times further away.
我们的邻居星系距离我们则足有100倍的距离
88.So, we can see far more detail in our galaxy than anyplace else.
因此，对我们自身所在星系的研究可以做到比其他任何一个星体 都更加透彻
89.And as you’ll see in a moment, the ability to see detail is key to this experiment.
就像我们马上就要谈到的 观察细节的能力对于我们这次实验至关重要
90.So, how do astronomers prove that there is a lot of mass inside a small volume?
这样一来 宇航员如何才能证明一个相对小的空间内存在很大的质量呢
91.Which is the job that I have to show you today.
这正是我今天想要向大家展示的
92.And the tool that we use is to watch the way stars orbit the black hole.
我们将应用的工具就是 观测行星环绕黑洞的轨道
93.Stars will orbit the black hole in the very same way that planets orbit the sun.
行星环绕的黑洞的轨道 与行星环绕太阳类似
94.It’s the gravitational pull that makes these things orbit.
是重心牵引力 使这些星体按照轨道运行
95.If there were no massive objects these things would go flying off, or at least go at a much slower rate because all that determines how they go around
如果没有大质量的物体存在，这些星体都将四散而出 或者说至少运动的速率对大幅下降 这是因为，对它们如何运动起到决定性作用的是
96.is how much mass is inside its orbit.
它的轨道内部存在多少的物质
97.So, this is great, because remember my job is to show there is a lot of mass inside a small volume.
我们必须要清楚这一点，因为我的工作就是 证明一个小的空间内也存在大量的物质
98.So, if I know how fast it goes around, I know the mass.
因此，如果可以计算出它的运行速度，我便可以推断出质量
99.And if I know the scale of the orbit I know the radius.
更进一 步，如果可以知道轨道的范围，我们就可以计算出其半径
100.So, I want to see the stars that are as close to the center of the galaxy as possible.
这就是我希望可以尽可能选择 接近星系中心星体的原因
101.Because I want to show there is a mass inside as small a region as possible.
只有这样，我才能在尽可能小的空间内证实物质的存在
102.So, this means that I want to see a lot of detail.
也就说明，我需要观测大量的细节数据
103.And that’s the reason that for this experiment we’ve used the world’s largest telescope.
这就是我们为何采用世界上最大的望远镜 来做这个实验的原因
104.This is the Keck observatory. It hosts two telescopes with a mirror 10 meters, which is roughly the diameter of a tennis court.
这是keck天文台，它拥有2台镜头有10米长的望远镜 差不多 是一个网球场直径的长度
105.Now, this is wonderful because the campaign promise of large telescopes is that is that the bigger the telescope, the smaller the detail that we can see.
这一点很赞 因为大型望远镜总是承诺 望远镜越大 我们能观察到越小的细节。
106.But it turns out these telescopes, or any telescope on the ground has had a little bit of a challenge living up to this campaign promise.
然而，我们却发现这些或现有的所有望远镜 都与预期的表现有所差距
107.And that is because of the atmosphere.
这是因为大气环境
108.Atmosphere is great for us; it allows us to survive here on Earth.
地球大气层对我们人类至关重要 它保证了生命的存在
109.But it’s relatively challenging for astronomers who want to look through the atmosphere to astronomical sources.
但是对天文学家来说，它却是相对有挑战性的， 因为他们需要透过大气层来观测外部的世界
110.So, to give you a sense of what this is like, it’s actually like looking at a pebble at the bottom of a stream.
因此，为了让大家更好的理解 我用一个比喻 就像看一块小溪底的鹅卵石一样
111.Looking at the pebble on the bottom of the stream, the stream is continuously moving and turbulent, and that makes it very difficult to see the pebble on the bottom of the stream.
在看河底的鹅卵石时 溪水不断流动 使得观察底部的鹅卵石变的很困难
112.Very much in the same way, it’s very difficult to see astronomical sources, because of the atmosphere that’s continuously moving by.
同样的 正是因为大气层不停的流动 我们很难观测到清晰的外层
113.So, I’ve spent a lot of my career working on ways to correct for the atmosphere, to give us a cleaner view.
因此我花费了职业生涯中很长的时间来研究如何克服这一困难 来给大家带来一个更清晰的视野
114.And that buys us about a factor of 20.
这可以提高我们1／20的成功率
115.And I think all of you can agree that if you can figure out how to improve life by a factor of 20 you’ve probably improved your lifestyle by a lot,
我认为我们大家都认同这一点 如果可以提高生活质量1／20的水平 那么整体的生活水平将获得很大的改善
116.say your salary, you’d notice, or your kids, you’d notice.
拿薪水，或者你的孩子做个例子，你就会发现
117.And this animation here shows you one example of the techniques that we use, called adaptive optics.
这个动画展示了 自适应光学的应用例子
118.You’re seeing an animation that goes between an example of what you would see if you don’t use this technique, In other words, just a picture that shows the stars,
你可以看到一个动画呈现 一幅你只有不应用这个技术才可以看到的画面 换句话说，就是一幅星象图
119.And the box is centered on the center of the galaxy.
这个方块位于整个星系的中心
120.where we think the black hole is.
也就是黑洞的所在
121.So, without this technology you can’t see the stars.
因此，如果没有这项技术，我们无法看到星体
122.With this technology all of a sudden you can see it.
应用这项技术我们可以突然的看到它们
123.This technology works by introducing a mirror into the telescope optics system that’s continuously changing to counteract what the atmosphere is doing to you.
这项技术在望远镜的光学系统中增加了一块反光镜 并通过这种原理进行工作 这将持续的改变你对大气层作用的看法
124.So, it’s kind of like very fancy eyeglasses for your telescope.
因此，这就像给你的望远镜带上一付花式眼镜
125.Now, in the next few slides I’m just going to focus on that little square there.
现在，接下的几幅幻灯片中，我们将主要观察 那个小方块
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