了解宇宙是如何运行的（2010）

How the Universe Works S06E06

Part 2 Dec. 22, 2021, 7:23 p.m.

有很多方法可以做到这一点
There are many ways you can do this.
你可以从里面把它炸开
You can blast it out from the inside.
你可以把它从外面吸走
You can draw it out from the outside.
你可以把它加热，这样它就不再冷了
You can heat it up so it's no longer cold.
你可以把它用完
You can use it all up,
当然还有更多的方法可以阻止它
and there's even more ways you can stop it.
我们要做的就是弄清楚
What we have to do is figure out
在我们的星系中发生了什么
which way is happening in our galaxy.
也许罪魁祸首就在银河系内部
Perhaps the culprit is inside the Milky Way itself.
一条线索来自另外一个星系
A clue comes from another galaxy entirely.
这是 w2246-0526
This is w2246-0526.
科学家称它为一个热的、尘埃遮蔽的星系
Scientists call it a hot, dust-obscured galaxy,
简称为“热狗”
<热狗星系在类星体一集中提到过——译者注>
or "hot dog" for short.
这个星系距离我们125亿光年
This galaxy is 12 1/2 billion light-years away.
它是我们所知的宇宙中最明亮的星系
It's the most luminous galaxy we know of in the universe.
它有300万亿颗恒星那么亮
It has the light of 300 trillion stars.
强烈的光的来源不是它的恒星
The source of the intense light is not its stars,
而是在星系中心的一个神秘的物体
but a mysterious object at the galaxy's center.
它比银河系还要小一百万倍
It's a million times smaller than the galaxy itself.
只有一样东西会即如此的渺小又如此的强大……
There's only one thing that small and that powerful...
一个超大质量黑洞
a supermassive black hole.
既然是超大质量黑洞，顾名思义
So, supermassive black holes, as the name suggests,
确实是超大质量的
are indeed supermassive.
它们的质量是太阳的数十亿倍
These are billions of times more massive than our sun.
它们都是庞然大物
These are gigantic objects.
超大质量黑洞的引力大得惊人
The gravity in the supermassive black hole is off the charts.
它吞噬了热狗星系中大量的
It sucks in incredible amounts
赖以形成恒星的气体
of the hot dog's vital star-forming gas.
当气体旋转形成一个圆盘时
And as the gas swirls to form a disk,
强烈的摩擦将其加热到数百万度
the intense friction superheats it to millions of degrees
在一些星系中，引发了巨大的喷射
and, in some galaxies, triggers huge jets.
当大量物质落入黑洞时
When a lot of material falls onto that black hole,
就会产生难以置信的高能喷流
it creates incredibly energetic jets
直径可达数万光年
that can be tens of thousands of light-years across.
就好像突然之间，星系的中♥央♥
All of a sudden, you have this blowtorch
出现一支喷枪
in the middle of the galaxy.
黑洞喷流对星系是有害的
Black hole jets are bad for galaxies
因为它们可以阻止恒星的形成
because they can shut down star formation.
它们可以加热气体，把气体吹出星系
They can heat gas up, blow gas out of galaxies,
它们真的可以杀死星系
and they could really kill them.
一个超大质量的黑洞正在烹制“热狗”
A supermassive black hole is cooking the hot dog.
所以在银河系中心也发生了类似的事情
So it's something similar happening at the center of the milky way.
2016年，哈佛大学的科学家发现了确凿的证据
In 2016, scientists at Harvard discovered damning evidence
很可能将银河系的超大质量黑洞
that may link the Milky Way's supermassive black hole
与我们星系的消亡联♥系♥起来
to the galaxy's demise.
就像热狗星系一样
Just like the hot dog,
银河系也被一大♥片♥喷发出来的气体所包围
the Milky Way is surrounded by a vast cloud of blown-out gas,
科学家们追踪到了这些气体的源头……
and the scientists traced the gas back to its source...
人马座a星，我们的超大质量黑洞
Sagittarius a-star, our supermassive black hole.
事实证明，我们的超大质量黑洞
Well, it turns out our supermassive black hole
在600万年前遇到了一点小麻烦
had a bit of a hiccup about 6 million years ago.
有证据表明一定有某种物质
There's evidence that some matter must have fallen
掉进了黑洞，如果它掉进地太快
into that black hole, and if it fell in too quickly,
就会由于自身的摩擦而过热
it would have gotten superheated by its own friction,
这在某种意义上，就像爆♥炸♥一样
and this would have acted, in a sense, like an explosion.
那是一个大事件
And that event was huge.
我们的星系排出了数量惊人的气体……
Our galaxy expelled an incredible amount of gas...
是太阳质量的1300亿倍
130 billion times the mass of the Sun.
有大量的气体
Large amount of gas.
这一事件对星系内部
This event must have been very catastrophic
一定是灾难性的
for the inner parts of the galaxy.
幸运的是，地球在银河系的外♥围♥
Luckily, Earth is in the outer parts of the galaxy,
在那里我们能够逃过一劫
where we were able to survive this event.
这就是确凿的证据吗？
Is this the smoking gun?
我们的超大质量黑洞正在杀死银河系吗？
Is our own supermassive black hole killing the Milky Way?
证据似乎越来越多
The evidence seems to mount up.
但人马座a星有不在场证明
But Sagittarius a-star has an alibi.
它爆发得太晚了
It exploded too late.
人马座a星在600万年前
Sagittarius a-star got very active,
非常活跃，非常具有爆♥炸♥性
very explosive about 6 million years ago,
但那是最近的事，它不应该真正影响
but that's so recent, it shouldn't have really affected
恒星的形成速率
the star formation rates.
还有别的事情在发生
Something else is going on.
除了黑洞，肯定还有其他的罪魁祸首
There must be another culprit besides the black hole.
研究表明，我们的超大质量黑洞必须
Studies suggest our supermassive black hole must have been active
在数亿年前就活跃
hundreds of millions of years ago
才能阻止我们星系中所有恒星的形成
to stop all star formation in our galaxy.
但那时的人马座a星并不活跃
Sagittarius a-star wasn't active at that time,
所以它被排除怀疑
so it's no longer a suspect.
科学家们正在寻找另一种星系杀手
The hunt is on for a different galaxy killer,
他们正在扩大调查范围
and scientists are widening the investigation.
也许凶手不在银河系里
Maybe the killer isn't inside our galaxy.
说不定有可能是肇事逃逸
It could be that we suffered a hit-and-run.
银河系的恒星生产机制正在崩溃
Star production in the Milky Way is breaking down.
我们的星系正在消亡
Our galaxy is dying,
天文学家正在检查它的身体以寻找线索
and astronomers are examining the body for clues.
银河系的圆盘由三个部分组成……
The Milky Way's disk is made up of three sections...
一个银心，星系超大质量黑洞的所在地……
A nucleus, home to the galaxy's supermassive black hole...
一个是直径达1万光年的致密中♥央♥凸起
a dense, central bulge 10,000 light-years across,
以及螺旋臂……
and the spiral arms...
充满了气体，尘埃和数十亿颗恒星
Full of gas, dust, and billions of stars.
旋臂应该是平的，但它们却是波纹状的
The spiral arms should be flat, but they're rippling.
这是否会是我们的星系正在消亡的线索吗？
Is this a clue for why our galaxy is dying?
今天，我们观察银河系的边缘
Today, we look at the edge of the Milky Way,
在它的气体中看到了神秘的波纹
and we see mysterious ripples in its gas,
我们想知道，它的起源是什么？
and we wonder, what's the origin?
一定是什么原因造成的
Something must have caused it to happen.
这种事不会自己发生的
Something like that just doesn't happen on its own.
真正的问题是，为什么会这样？
The real question is, why?
不管是什么引起的涟漪，它并没有留下来
Whatever caused the ripples didn't hang around.
这是银河肇事逃逸的证据吗？
Is this evidence of a galactic hit-and-run?
2016年一月
January 2016.
研究维斯塔天文望远镜数据的天文学家
Astronomers studying data from the vista telescope
发现了一些不可思议的东西……
discover something incredible...
三个邻近恒星
three nearby stars.
就它们自己而言，没什么特别的
On their own, nothing special,
除了最近它们刚刚离开我们的星系
except they've recently left our galaxy,
它们正以每小时35万英里的速度飞行
and they're traveling at 350,000 miles an hour.
所以，我们发现这些恒星
So, we've discovered these stars that are careening
正以超高速偏离银河系
out of the galaxy at super-high velocities.
这三颗恒星会以某种方式
Could these three stars somehow be responsible
导致银河系盘的扭曲吗？
for warping the Milky Way's disk?
好吧,绝对不可能
Well, absolutely not.
银河系比三颗恒星要大得多
The Milky Way is so much more massive than just three stars.
三颗恒星不可能扭曲一个星系
Three stars alone can't warp a galaxy,
但是这三颗恒星可以代表更多的这样的恒星存在
but those three stars can be indicative of more stars.
它们可以表明，比如说
They can be indicative of the presence of, say,
一个矮星系，而它却可以扭曲星系
a dwarf galaxy, and that can warp the galaxy.
矮星系有很多
Dwarf galaxies are abundant.
但是相对于银河系大小的星系来讲
But a tiny fraction of the size of a major galaxy,
它们只有一小部分那么大
like the Milky Way.
所以它们很难被发现
So they're difficult to detect.
但这三颗明亮的恒星表明在银河系的边缘外
But these three bright stars show there's a dwarf galaxy
隐藏着一个矮星系
hiding beyond the edge of the Milky Way.
科学家们可以通过研究这三颗恒星
And scientists can study the trio of stars
让时间倒流
to rewind the clock
追溯矮星系过去的运动轨迹
and track back the past movements of the dwarf galaxy.
模拟表明，数百万年前
Simulations suggest that millions of years ago,
这个矮星系
this dwarf galaxy
穿过了银河系的平面