Andrea Ghez: The hunt for a supermassive black hole

譯者: yuanyuan liu 審譯者: Zhu Jie

How do you observe something you can't see?

要如何去觀察看不見的東西？

This is the basic question of somebody who's interested

對於有興趣尋找和研究黑洞的人來說，

in finding and studying black holes.

這是個很基本的問題。

Because black holes are objects

因為黑洞這種物體的引力非常強大，

whose pull of gravity is so intense

that nothing can escape it, not even light,

什麼都逃不過黑洞，連光線都不能，

so you can't see it directly.

所以我們無法直接看到它。

So, my story today about black holes

我今天要談的是一種特定的黑洞。

is about one particular black hole.

I'm interested in finding whether or not

我想要知道

在我們的銀河中心，是否有所謂的

there is a really massive, what we like to call

"supermassive" black hole at the center of our galaxy.

「超大質量黑洞」存在。

And the reason this is interesting is that

這點很有趣的原因

是我們有機會可以證明

it gives us an opportunity to prove

whether or not these exotic objects really exist.

這些奇特的物體是否真的存在。

And second, it gives us the opportunity

第二，我們也有機會

to understand how these supermassive black holes

能了解這些超大質量黑洞

interact with their environment,

如何和我們的環境互動，

and to understand how they affect the formation and evolution

並了解它們如何影響

它們所屬銀河的形成和演化。

of the galaxies which they reside in.

So, to begin with,

所以，首先，

we need to understand what a black hole is

我們得要了解黑洞是什麼，

so we can understand the proof of a black hole.

接著才能了解黑洞存在的證據。

So, what is a black hole?

所以，黑洞是什麼？

Well, in many ways a black hole is an incredibly simple object,

在許多層面上， 黑洞是個非常簡單的物體，

because there are only three characteristics that you can describe:

因為能夠用來描述 黑洞的特徵只有三項：

the mass,

質量、自旋，以及電荷。

the spin, and the charge.

And I'm going to only talk about the mass.

而我只打算談質量。

So, in that sense, it's a very simple object.

在這方面黑洞是很簡單的物體。

但在另一方面， 它又是非常複雜的物體，

But in another sense, it's an incredibly complicated object

that we need relatively exotic physics to describe,

我們需要用很奇特的物理才能描述它，

and in some sense represents the breakdown of our physical understanding

且在某種意義上， 它打破了我們對宇宙的物理認知。

of the universe.

But today, the way I want you to understand a black hole,

要了解黑洞以證明它的存在，

for the proof of a black hole,

is to think of it as an object

我要你們把它想像成一個物體，

whose mass is confined to zero volume.

它的質量被局限在零體積當中。

So, despite the fact that I'm going to talk to you about

所以，儘管我要跟大家談的 是超大質量的物體

an object that's supermassive,

——我馬上就會解釋這一點——

and I'm going to get to what that really means in a moment,

it has no finite size.

它沒有大小限制。

So, this is a little tricky.

所以，這有點難搞。

But fortunately there is a finite size that you can see,

但幸運的是，

有種大小限制是我們看得見的，

and that's known as the Schwarzschild radius.

那就是我們所知的史瓦西半徑。

And that's named after the guy who recognized

史瓦西是發現 這個半徑有多重要的人。

why it was such an important radius.

This is a virtual radius, not reality; the black hole has no size.

這個半徑是虛擬的，不是真實的；

黑洞沒有大小。

So why is it so important?

那它為什麼如此重要？

It's important because it tells us

是因為它告訴我們

that any object can become a black hole.

任何物體都能夠變成黑洞；

That means you, your neighbor, your cellphone,

包括你、你的鄰居、你的手機、

the auditorium can become a black hole

觀眾席都可能變成黑洞，

if you can figure out how to compress it down

只要你能想辦法把它壓縮到

to the size of the Schwarzschild radius.

史瓦西半徑的大小即可。

At that point, what's going to happen?

屆時會怎樣？

At that point gravity wins.

屆時引力就贏了。

Gravity wins over all other known forces.

引力會勝過所有其他已知的力。

And the object is forced to continue to collapse

因此，物體被迫持續塌陷， 成為無限小的物體。

to an infinitely small object.

And then it's a black hole.

接著，就成了黑洞。

So, if I were to compress the Earth down to the size of a sugar cube,

所以，如果我把地球 壓縮到方糖的大小，

it would become a black hole,

它就會變成黑洞，

because the size of a sugar cube is its Schwarzschild radius.

因為方糖的大小 就是地球的史瓦西半徑。

這裡的關鍵在於 找出史瓦西半徑是多少。

Now, the key here is to figure out what that Schwarzschild radius is.

And it turns out that it's actually pretty simple to figure out.

結果發現，其實很容易找出來。

It depends only on the mass of the object.

史瓦西半徑只和物體的質量有關。

Bigger objects have bigger Schwarzschild radii.

較大的物體，史瓦西半徑也較大。

Smaller objects have smaller Schwarzschild radii.

較小的物體，史瓦西半徑也較小。

So, if I were to take the sun

如果我把太陽

and compress it down to the scale of the University of Oxford,

壓縮到牛津大學的尺寸，

it would become a black hole.

它就會變成黑洞。

So, now we know what a Schwarzschild radius is.

現在我們知道 史瓦西半徑是什麼了。

And it's actually quite a useful concept,

它其實是個很有用的觀念，

because it tells us not only

因為它不僅能告訴我們 黑洞何時會形成，

when a black hole will form,

but it also gives us the key elements for the proof of a black hole.

也給了我們證明 黑洞存在的關鍵元素。

I only need two things.

我只需要兩樣東西：

I need to understand the mass of the object

宣稱是黑洞的物體， 我需要知道它的質量，

I'm claiming is a black hole,

and what its Schwarzschild radius is.

還有它的史瓦西半徑。

因為史瓦西半徑是由質量來決定， 其實我只需要知道一樣即可。

And since the mass determines the Schwarzschild radius,

there is actually only one thing I really need to know.

So, my job in convincing you

因此，我若要說服你有個黑洞存在，

that there is a black hole

is to show that there is some object

我就得證明有某個物體

that's confined to within its Schwarzschild radius.

被局限在它的史瓦西半徑中。

And your job today is to be skeptical.

今天各位就儘管抱持懷疑的態度。

Okay, so, I'm going to talk about no ordinary black hole;

好，我要談的不是平凡的黑洞，

I'm going to talk about supermassive black holes.

而是超大質量黑洞。

So, I wanted to say a few words about what an ordinary black hole is,

我想要簡單說一下 平凡的黑洞是什麼，

as if there could be such a thing as an ordinary black hole.

講得好像黑洞可以很平凡。

An ordinary black hole is thought to be the end state

一般認為，大質量的天體 在滅亡後的狀態

of a really massive star's life.

就是平凡的黑洞。

So, if a star starts its life off

如果有一個天體在生命之初的質量 就有比太陽大很多，

with much more mass than the mass of the Sun,

it's going to end its life by exploding

它滅亡的方式會是爆炸，

and leaving behind these beautiful supernova remnants that we see here.

並留下這些美麗的超級新星殘骸。

And inside that supernova remnant

在這些超級新星殘骸中， 會有一個小黑洞，

is going to be a little black hole

that has a mass roughly three times the mass of the Sun.

質量大約是太陽的三倍。

On an astronomical scale

從天文學的角度來看，

that's a very small black hole.

這個黑洞算非常小。

Now, what I want to talk about are the supermassive black holes.

我想要談的是超大質量黑洞。

And the supermassive black holes are thought to reside at the center of galaxies.

一般認為超大質量黑洞 位在銀河的中心。

And this beautiful picture taken with the Hubble Space Telescope

這張用哈伯太空望遠鏡 拍攝的美麗照片

shows you that galaxies come in all shapes and sizes.

讓我們看到有各種 形狀、大小的銀河。

There are big ones. There are little ones.

有大的、有小的。

Almost every object in that picture there is a galaxy.

在那張照片上幾乎 每個物體都是一個銀河。

And there is a very nice spiral up in the upper left.

為了讓你對規模有個概念，

And there are a hundred billion stars in that galaxy,

左上角有個漂亮的螺旋 是個有千億個天體的銀河。

just to give you a sense of scale.

And all the light that we see from a typical galaxy,

而我們看到來自典型銀河的光， 比如我們在這裡所看見的銀河，

which is the kind of galaxies that we're seeing here,

comes from the light from the stars.

是來自恆星的光。

So, we see the galaxy because of the star light.

我們能看見銀河是因為恆星的光。

Now, there are a few relatively exotic galaxies.

有少數銀河，相對之下很奇特。

I like to call these the prima donna of the galaxy world,

我想把它們稱為 銀河世界的女主角，

because they are kind of show offs.

因為它們有點愛現。

And we call them active galactic nuclei.

我們稱它們為活躍星系核。

And we call them that because their nucleus,

會這麼稱呼是因為它們的核，

or their center, are very active.

或說它們的中心，非常活躍。

So, at the center there, that's actually where

其實大部分的星光來自這個中心。

most of the starlight comes out from.

And yet, what we actually see is light

但，我們看到的光

that can't be explained by the starlight.

其實無法用星光來解釋。

It's way more energetic.

這些光的能量更強。

事實上，在少數例子中， 就像這裡看到的這些。

In fact, in a few examples it's like the ones that we're seeing here.

There are also jets emanating out from the center.

從中心還會有噴出物。

Again, a source of energy that's very difficult to explain

如果你把銀河想成是恆星所構成的，

這個能量來源也非常難解釋。

if you just think that galaxies are composed of stars.

So, what people have thought is that perhaps

所以有人認為也許 有超大質量黑洞在那裡，

there are supermassive black holes

which matter is falling on to.

物質會掉進去。

So, you can't see the black hole itself,

你無法看見黑洞本身，

but you can convert the gravitational energy of the black hole

但你能把黑洞的引力

into the light we see.

轉換成為可見光。

So, there is the thought that maybe supermassive black holes

所以會有人認為在銀河的中心 有超大質量黑洞存在。

exist at the center of galaxies.

But it's a kind of indirect argument.

但這種論點沒有直接證據。

Nonetheless, it's given rise to the notion

無論如何，這就帶出了一個想法：

that maybe it's not just these prima donnas

也許不是只有這些女主角 才有超大質量黑洞，

that have these supermassive black holes,

而是所有的銀河在中心處

but rather all galaxies might harbor these

都有這種超大質量黑洞。

supermassive black holes at their centers.

And if that's the case -- and this is an example of a normal galaxy;

如果真是這樣……

這個例子是正常的銀河， 我們看見的光都是星光。

what we see is the star light.

And if there is a supermassive black hole,

若有個超大質量黑洞存在，

what we need to assume is that it's a black hole on a diet.

我們就得假設照片裡 是個在節食的黑洞，

Because that is the way to suppress the energetic phenomena that we see

因為那樣才能壓抑 我們在活躍星系核

in active galactic nuclei.

看到的能量現象。

If we're going to look for these stealth black holes

如果我們要去找

這些躲在銀河中心處的黑洞，

at the center of galaxies,

the best place to look is in our own galaxy, our Milky Way.

最理想的目標就是 在我們自己的銀河中尋找。

And this is a wide field picture

這是張廣視野的照片，

taken of the center of the Milky Way.

照片上的是銀河的中心。

And what we see is a line of stars.

我們看到的是一列恆星。

And that is because we live in a galaxy which has

那是因為我們所處的銀河 結構是扁盤狀的。

a flattened, disk-like structure.

我們置身其中，看向它的中心時，

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,

會看到定義銀河平面的這個平面，

or line that defines the plane of the galaxy.

或者定義銀河平面的那條線。

Now, the advantage of studying our own galaxy

研究我們自己的銀河有個好處，

is it's simply the closest example of the center of a galaxy

因為這是離我們最近的銀河中心，

that we're ever going to have, because the next closest galaxy

第二近的銀河距離還要遠一百倍。

is 100 times further away.

So, we can see far more detail in our galaxy

所以，在我們的銀河中能看到的 細節會比其他地方多很多。

than anyplace else.

And as you'll see in a moment, the ability to see detail

等下就會看到，

這個實驗的關鍵 在於看見細節的能力。

is key to this experiment.

So, how do astronomers prove that there is a lot of mass

所以天文學家要如何證明

在很小的體積中有很大的質量？

inside a small volume?

Which is the job that I have to show you today.

這就是今天我要展示給各位看的。

And the tool that we use is to watch the way

我們用的工具，

是觀察恆星繞行黑洞的方式。

stars orbit the black hole.

Stars will orbit the black hole

恆星繞行黑洞的方式

in the very same way that planets orbit the sun.

和行星繞行太陽的方式一樣。

It's the gravitational pull

是引力讓它們繞行。

that makes these things orbit.

If there were no massive objects these things would go flying off,

如果沒有大質量物體， 它們就會飛走，

or at least go at a much slower rate

或至少行進速度慢很多，

because all that determines how they go around

因為決定它們如何繞行的

就只是軌道內有多少質量。

is how much mass is inside its orbit.

So, this is great, because remember my job is to show

這樣很好，因為我就是要說明 在小體積內有大質量。

there is a lot of mass inside a small volume.

So, if I know how fast it goes around, I know the mass.

若我知道繞行速度， 就能知道質量。

And if I know the scale of the orbit I know the radius.

若我知道軌道的大小， 就能知道半徑。

So, I want to see the stars

所以我會想研究的恆星，

that are as close to the center of the galaxy as possible.

是越靠近銀河的中心越理想。

Because I want to show there is a mass inside as small a region as possible.

因為我想證明在小區域內 有大質量，且那個區域越小越好。

So, this means that I want to see a lot of detail.

這就表示我想要看到很多細節。

And that's the reason that for this experiment we've used

這就是為什麼我們把世界上 最大的望遠鏡用在這個實驗上。

the world's largest telescope.

This is the Keck observatory. It hosts two telescopes

這是凱克天文台，有兩座望遠鏡，

搭配十公尺的鏡子， 大約等同於網球場的寬度。

with a mirror 10 meters, which is roughly

the diameter of a tennis court.

Now, this is wonderful,

這很棒，

because the campaign promise

因為大型望遠鏡

of large telescopes is that is that the bigger the telescope,

宣稱尺寸越大，

the smaller the detail that we can see.

看到的細節就越細。

But it turns out these telescopes, or any telescope on the ground

但結果發現，這些 或地面上的任何望遠鏡

has had a little bit of a challenge living up to this campaign promise.

或多或少難以實現這承諾。

And that is because of the atmosphere.

原因是大氣。

Atmosphere is great for us; it allows us

對我們來說，大氣很棒， 它讓我們能在地球上生存。

to survive here on Earth.

But it's relatively challenging for astronomers

但對於想要穿過大氣 去看天體的天文學家而言，

who want to look through the atmosphere to astronomical sources.

就成了障礙。

So, to give you a sense of what this is like,

用個比喻讓各位了解，

it's actually like looking at a pebble

感覺就像是去看溪底的小卵石。

at the bottom of a stream.

Looking at the pebble on the bottom of the stream,

看溪底的小卵石，

the stream is continuously moving and turbulent,

溪流持續在流動，起起伏伏，

and that makes it very difficult to see the pebble on the bottom of the stream.

因此很難看見溪底的小卵石。

Very much in the same way, it's very difficult

非常類似的道理， 我們很難看見天文源頭，

to see astronomical sources, because of the

因為大氣持續流動。

atmosphere that's continuously moving by.

So, I've spent a lot of my career working on ways

職涯裡，我投入大把時間 研究如何針對大氣做校調，

to correct for the atmosphere, to give us a cleaner view.

以看得更清楚。

And that buys us about a factor of 20.

結果讓我們有二十倍的改善。

And I think all of you can agree that if you can

我想大家都同意， 若你有辦法將生活改善二十倍，

figure out how to improve life by a factor of 20,

you've probably improved your lifestyle by a lot,

你的生活方式可能會大大改善，

say your salary, you'd notice, or your kids, you'd notice.

比如你的薪水或你的孩子， 都是你能注意得到的改善。

And this animation here shows you one example of

這個動畫是我們使用 「自調光學」技術呈現出來的例子。

the techniques that we use, called adaptive optics.

You're seeing an animation that goes between

這個動畫展現的是 不用這項技術會看到的景象

an example of what you would see if you don't use this technique --

in other words, just a picture that shows the stars --

——換言之，就是一個大約的樣子——

and the box is centered on the center of the galaxy,

轉換到用這項技術後，

清楚看見銀河中心的方格， 即我們認為的黑洞所在。

where we think the black hole is.

So, without this technology you can't see the stars.

所以，沒有這項技術， 你就看不見那些恆星。

With this technology all of a sudden you can see it.

有了這項技術，突然就能看見了。

This technology works by introducing a mirror

這項技術的原理是將一面鏡子 放入望遠鏡光學系統中，

into the telescope optics system

that's continuously changing to counteract what the atmosphere is doing to you.

它會不變改變， 抵消大氣對你產生的影響。

So, it's kind of like very fancy eyeglasses for your telescope.

就像是你的望遠鏡 配戴了一副很炫的眼鏡。

Now, in the next few slides I'm just going to focus on

接下來的幾張投影片 會著重在這個小方形上。

that little square there.

So, we're only going to look at the stars inside that small square,

我們已經看到所有恆星， 但現在只要看在小方形裡的，

although we've looked at all of them.

So, I want to see how these things have moved.

我想要看它們如何移動。

And over the course of this experiment, these stars

在這個實驗的過程中， 這些恆星移動的距離非常大。

have moved a tremendous amount.

So, we've been doing this experiment for 15 years,

這個實驗進行了十五年， 我們已經看到恆星繞了一整圈。

and we see the stars go all the way around.

Now, most astronomers have a favorite star,

大部分的天文學家 都有個最愛的恆星，

and mine today is a star that's labeled up there, SO-2.

今天我最愛的是標記為 SO-2 的那一個。

Absolutely my favorite star in the world.

世界上我最喜歡的恆星絕對是它。

And that's because it goes around in only 15 years.

因為它只花了十五年就繞了一圈。

And to give you a sense of how short that is,

讓各位更清楚十五年有多短，

the sun takes 200 million years to go around the center of the galaxy.

太陽繞著銀河的中心 轉一圈要兩億年。

Stars that we knew about before, that were as close to the center of the galaxy

以前我們所知最靠近 銀河中心的恆星

as possible, take 500 years.

也要花五百年。

And this one, this one goes around in a human lifetime.

這個恆星可以在人類 一生內就繞一圈回來。

That's kind of profound, in a way.

那在某種意義上是挺深的。 但這是實驗的關鍵。

But it's the key to this experiment. The orbit tells me

這個軌道讓我知道 在極小的半徑內有多少質量。

how much mass is inside a very small radius.

So, next we see a picture here that shows you

接著，從這張照片 可以看到在實驗之前，

before this experiment the size to which we could

我們能將銀河中心的質量 局限在多大的範圍內。

confine the mass of the center of the galaxy.

What we knew before is that there was four million

我們以前知道，在那個圓圈中間 有太陽四百萬倍的質量，

times the mass of the sun inside that circle.

And as you can see, there was a lot of other stuff inside that circle.

你可以看到， 圓圈中還有許多其他東西。

You can see a lot of stars.

可以看到很多恆星。

So, there was actually lots of alternatives

所以，其實還有很多其他可能，

to the idea that there was a supermassive black hole at the center of the galaxy,

不見得在銀河中心一定 有一個超大質量黑洞，

because you could put a lot of stuff in there.

因為裡面可能有很多別的。

But with this experiment, we've confined

但在這個實驗中， 我們能把同樣的質量

that same mass to a much smaller volume

局限在更小更小的體積中， 小了足足一萬倍。

that's 10,000 times smaller.

And because of that, we've been able to show

因此，我們能證明 那裡有一個超大質量黑洞。

that there is a supermassive black hole there.

To give you a sense of how small that size is,

讓你更清楚那是多小， 那就是我們太陽系的大小。

that's the size of our solar system.

So, we're cramming four million times the mass of the sun

所以我們是把四百萬倍的太陽質量

into that small volume.

塞到那個小體積中。

Now, truth in advertising. Right?

廣告中也有事實，對吧？

I have told you my job is to get it down to the Schwarzchild radius.

我說過，我的工作是要 將它縮小到史瓦西半徑。

And the truth is, I'm not quite there.

事實上，我還沒做到。

But we actually have no alternative today

但對於這種質量的集中現象，

to explaining this concentration of mass.

現今已經沒有其他可能的解釋。

And, in fact, it's the best evidence we have to date

事實上，它是我們至今的最佳證據，

不僅能證明有超大質量黑洞 存在於我們自己銀河的中心，

for not only existence of a supermassive black hole

at the center of our own galaxy, but any in our universe.

還能證明在宇宙任何銀河都有。

So, what next? I actually think

所以接下來呢？

其實我認為以現今的科技， 已無法再做得更好，

this is about as good as we're going to do with today's technology,

so let's move on with the problem.

所以我們就談別的吧。

So, what I want to tell you, very briefly,

我想要用幾個例子，簡短告訴各位

is a few examples

現今我們可以在銀河中心 做什麼有趣的事，

of the excitement of what we can do today

at the center of the galaxy, now that we know that there is,

因為我們已經知道， 或至少我們相信，

or at least we believe,

that there is a supermassive black hole there.

那裡有個超大質量黑洞。

And the fun phase of this experiment

這個實驗很有趣的階段

is, while we've tested some of our ideas

是當我們測試一些想法，

about the consequences of a supermassive black hole

關於銀河中心有個超大質量黑洞 會有什麼後果的想法時，

being at the center of our galaxy,

almost every single one

我們發現幾乎每個想法 都和我們實際所見到的不一致。

has been inconsistent with what we actually see.

And that's the fun.

這就是有趣之處。

So, let me give you the two examples.

讓我舉兩個例子。

You can ask, "What do you expect

你可以問：「你預期老恆星會怎樣？

for the old stars, stars that have been around the center of the galaxy

在銀河中心附近已經很久的恆星，

for a long time, they've had plenty of time to interact with the black hole."

它們有很多時間 和黑洞發生交互作用。」

What you expect there is that old stars

你會預期老恆星應該會 非常集中在黑洞附近。

should be very clustered around the black hole.

You should see a lot of old stars next to that black hole.

你應該會看到黑洞旁邊 有許多老恆星。

相對的，年輕的恆星，

Likewise, for the young stars, or in contrast, the young stars,

they just should not be there.

它們不應該在那裡。

A black hole does not make a kind neighbor to a stellar nursery.

黑洞不是孕育恆星的好鄰居。

To get a star to form, you need a big ball of gas and dust to collapse.

恆星的形成需要 大量氣體和塵埃往中心塌陷。

And it's a very fragile entity.

它是非常脆弱的實體。

And what does the big black hole do?

而大黑洞會怎樣？

It strips that gas cloud apart.

它會把氣體雲扯開。

It pulls much stronger on one side than the other

它在一邊的拉力遠大於另一邊， 因此氣體雲會被扯開。

and the cloud is stripped apart.

事實上，我們預期 在那個環境中不會有恆星形成，

In fact, we anticipated that star formation shouldn't proceed in that environment.

So, you shouldn't see young stars.

不該看見年輕的恆星。

So, what do we see?

然而我們看見了什麼？

Using observations that are not the ones I've shown you today,

使用一些我今天沒有 給各位看的觀察資料，

we can actually figure out which ones are old and which ones are young.

我們可以辨視出 哪些恆星老、哪些年輕。

The old ones are red.

老恆星是紅色的。

The young ones are blue. And the yellow ones, we don't know yet.

年輕恆星是藍色的。 我們還不清楚黃色的是什麼。

So, you can already see the surprise.

所以，已經可看到意料之外的現象。

There is a dearth of old stars.

老恆星不多，年輕恆星很多，

There is an abundance of young stars, so it's the exact opposite of the prediction.

和預測完全相反。

So, this is the fun part.

這就是有趣的部分。

And in fact, today, this is what we're trying to figure out,

我們正在努力想通這一點，

this mystery of how do you get --

這個謎題在於要如何解決這種矛盾。

how do you resolve this contradiction.

So, in fact, my graduate students

事實上，我的研究生此時此刻

are, at this very moment, today, at the telescope,

就在夏威夷的望遠鏡前

in Hawaii, making observations to get us

進行觀察，希望能 讓我們邁入下一階段，

hopefully to the next stage,

where we can address this question

我們才可以處理為什麼 有這麼多年輕恆星

of why are there so many young stars,

卻沒幾個老恆星的問題。

and so few old stars.

To make further progress we really need to look at the orbits

為了未來的進展， 我們需要去研究更遙遠恆星的軌道。

of stars that are much further away.

To do that we'll probably need much more

若要做到這一點， 我們需要比現今更精密的技術。

sophisticated technology than we have today.

Because, in truth, while I said we're correcting

因為，雖說我們針對 地球大氣做了修正，

for the Earth's atmosphere, we actually only

其實我們只修正了一半的錯誤。

correct for half the errors that are introduced.

We do this by shooting a laser up into the atmosphere,

我們的做法是將雷射射入大氣中，

and what we think we can do is if we

而我認為我們能做的 是再多發射一些，

shine a few more that we can correct the rest.

把剩下的錯誤修正，這是我們 接下來幾年希望做到的目標。

So this is what we hope to do in the next few years.

And on a much longer time scale,

更長遠來看，

what we hope to do is build even larger telescopes,

我們希望打造更大的望遠鏡，

because, remember, bigger is better in astronomy.

因為，別忘了， 在天文學上越大越好。

So, we want to build a 30 meter telescope.

我們想打造三十公尺的望遠鏡。

And with this telescope we should be able to see

有了它，我們應該能看見

stars that are even closer to the center of the galaxy.

更靠近銀河中心的恆星。

And we hope to be able to test some of

我們希望能測試一些 愛因斯坦的廣義相對論理論，

Einstein's theories of general relativity,

some ideas in cosmology about how galaxies form.

在宇宙論中一些 關於銀河形成的想法。

So, we think the future of this experiment

所以，我們認為這項實驗的未來

is quite exciting.

很讓人興奮。

So, in conclusion, I'm going to show you an animation

我要給大家看一支動畫作結，

that basically shows you how these

基本上，它會用 3D 方式呈現

orbits have been moving, in three dimensions.

這些軌道如何移動。

And I hope, if nothing else,

我希望，

I've convinced you that, one, we do in fact

至少我能說服大家，在銀河中心

have a supermassive black hole at the center of the galaxy.

的確有一個超大質量黑洞。

And this means that these things do exist in our universe,

那就表示我們的宇宙中 真的有這種黑洞，

and we have to contend with this, we have to explain

而我們必須要提出論據，

how you can get these objects in our physical world.

解釋在我們的物理世界中 怎麼會有這些物體存在。

Second, we've been able to look at that interaction

第二，我們能夠去研究

超大質量黑洞的交互作用方式，

of how supermassive black holes interact,

and understand, maybe, the role in which they play

也許還可以了解它們 在銀河形成當中所扮演的角色，

in shaping what galaxies are, and how they work.

及它們的運作方式。

And last but not least,

最後，也很重要的， 這一切之所以能夠實現，

none of this would have happened

without the advent of the tremendous progress

是因為科技前線的重大進展。

that's been made on the technology front.

And we think that this is a field that is moving incredibly fast,

我們認為這個領域的進展非常快，

and holds a lot in store for the future.

且對於未來會有很多貢獻。

Thanks very much.

非常謝謝大家。

(Applause)

（掌聲）