了解宇宙是如何运行的（2010）

How the Universe Works S09E09

Part 7 March 16, 2022, 8:56 a.m.

universe got so big so fast?
看到这些红外图像显示了星系中心
Seeing these infrared images
showing pairs of supermassive
有一对对的超大质量黑洞
black holes at the centers
of galaxies
并表明这可能非常普遍
and showing that
this could be very common
这让我大吃一惊
just is mind-blowing to me.
我们之所以看到一对对超大质量黑洞
The reason we see pairs of
supermassive black holes
是因为两个星系合并在一起
is because two galaxies
merged together.
明加雷利:在我们的宇宙运行图中
MINGARELLI: In our picture of
how the universe works,
星系开始时是较小的星系，然后通过与其他星系
galaxies start off as smaller
galaxies and grow by merging
合并而成长
with other galaxies.
所以他们会互相厮杀
So they'll be whooshing
around each other
把对方撕成碎片
and tearing each other up.
实际上是非常暴♥力♥的
It's actually quite violent.
当星系合并时，我们认为它们中心的
When galaxies merge,
we think their central
超大质量黑洞也会合并
supermassive black holes
also merge,
相互撞击并结合形成一个
smashing into each other
and combining to build
更大的黑洞
a larger black hole.
星系规模的合并可能是
Galaxy-scale mergers
can be one of the most
超大质量黑洞最有效的增长机制之一
efficient growth mechanisms
for supermassive black holes.
也许，在早期宇宙中
Maybe,
in the early universe,
恒星质量或中等质量的黑洞
black holes of stellar
or intermediate mass
反复合并，越来越重
merged repeatedly,
getting heavier
直到它们变成超大质量
and heavier until
they became super massive.
斯特劳恩:我们真的不知道
STRAUGHN: We don't
really know how common
超大质量黑洞合并在早期宇宙中有多普遍
supermassive black hole mergers
were in the early universe,
但我们认为它们比今天更普遍
but we think they were more
common than they are today,
因为那时星系靠得更近
because galaxies were
closer together.
要形成我们今天看到的最大的
It would have taken
millions of mergers to build up
超大质量黑洞，需要进行数百万次合并
the largest supermassive
black holes we see today,
这可能是一个艰巨的任务
which could have been
a tall order.
还有一个问题
There's another problem, too.
我们从未亲眼目睹过
We've never witnessed
a supermassive
超大质量黑洞的合并过程
black hole merger in the act.
我们已经看到超大质量黑洞准备要进行合并
We've seen supermassive black
holes on their way to merging,
我们也看到了一些我们认为已经合并的黑洞
and we've seen ones that we
think had gone through mergers.
但我们现在还没抓到一个合并瞬间
But we haven't caught one
in the moment.
当超大质量黑洞开始合并时
As supermassive
black holes start merging,
它们会围绕彼此旋转
they spiral around each other,
距离越近，速度越快
getting faster and faster
the closer they get.
但要最终
But for them
to finally merge together
合并成一个黑洞
into a single black hole,
它们需要失去天文学家所说的
they need to lose what
astronomers call
轨道能量
orbital energy.
超大质量黑洞的合并
The merger of supermassive
black holes means that
意味着它们的轨道
their orbits have to decay
必须衰减才能越来越近
for them to get closer
and closer together.
所以为了让轨道衰变
So in order
for an orbit to decay,
轨道能量必须转移到某个地方
that orbital energy
has to go somewhere.
为了失去能量
To lose energy,
合并的超大质量黑洞开始扰乱
the merging supermassive black
holes start disrupting
附近恒星的轨道
the orbits of nearby stars,
使它们偏离轨道
throwing them off their paths.
霍普金斯:所以，像我们恒星一样的
HOPKINS: So something small
and puny that weighs
重量只有一个太阳的微小物体
just one sun like our own star
will often get in
经常会进入双黑洞系统的轨道，然后会像火箭一样
the path of these two
and just get rocketed out,
被发射出去，甚至可能会被完全甩出星系
potentially unbound and flung
out of the galaxy entirely.
每一次超大质量黑洞抛出一颗恒星
Each time
the supermassive black holes
它们就会损失更多的轨道能量
fling out a star,
they lose more orbital energy.
它们就会越来越近
They get closer and closer.
但最终，他们把所有的恒星都踢出去了
But eventually,
they kicked out all the stars.
没有东西剩下了
There's nothing left.
合并陷入僵局
The merger stalls.
就像高中舞会上的一对情侣
Like two sweethearts
at a high school prom,
超大质量的黑洞跳得尽可能近
the supermassive black holes
dance as close as they can,
但身体接触是不允许的
but physical contact
is not allowed.
所以这两个黑洞可能会
So these two black holes
could end up spiraling
绕着对方旋转几十亿年
around each other for billions
and billions of years.
这被称为最后的秒差距问题
This is called the final
parsec problem.
明加雷利: 1980年，有一篇著名的论文
MINGARELLI: In 1980,
there was a famous paper,
讨论了这个问题
which addressed this issue that
超大质量黑洞彼此之间只能到达
supermassive black holes
can only get to
1秒差距内，也就是3光年内
within about one parsec, or
three light-years, of each other
之后就无法合并或停滞不前
before they can't merge
or they stall.
我们相信超大质量黑洞一定会合并
We believe that supermassive
black holes must merge.
我们知道星系会合并，所以如果黑洞不会合并
We know that galaxies merge,
and so if the black holes
我们就会看到很多黑洞在周围漂浮
didn't merge, we'd see lots of
black holes floating around.
我们没有看到——至少中间总有一个
And we don't -- there's always
one in the middle.
那么它们是如何合并的呢？
So how do they merge?
2019年，我们发现了一些东西
In 2019, we found
something that appears
似乎解决了最后的秒差距问题——
to solve
the final parsec problem --
一个正在合并的星系
A galaxy in the middle
of a merger
其中包含的超大质量黑洞不是两个
that contains not two
supermassive black holes,
而是三个
but three.
明加雷利:三个超大质量黑洞
MINGARELLI: Three supermassive
black holes.
这真是太酷了
Now that's really cool.
有时会有三个星系
Sometimes you can have
three galaxies
合并成一个星系团
that are merging together in
a galaxy cluster.
然后有三个超大质量黑洞
Then you have three
supermassive black holes.
在这个层面上
At this point is,
几乎不可能有最后的
it's virtually
impossible for there to be
秒差距问题
a final parsec problem.
那么第三个黑洞是如何解决最后的
Here's how a third
black hole solves the final
秒差距问题
parsec problem.
其中两个黑洞的轨道越来越近
Two of the black holes orbit
closer and closer,
喷射出的恒星失去能量
ejecting stars to lose energy.
三号♥黑洞也加入了进来
Black hole number three