了解宇宙是如何运行的（2010）

How the Universe Works S06E05

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

visible billions of light-years away.
那里就是物质密度和温度上升的地方
That's where stuff gets dense and hot,
也就是类星体
and there, you have a quasar.
因此，即使黑洞是宇宙中最黑暗的物体
So even though black holes are the darkest objects
但反过来，他们也会
in the universe, they, in turn,
为宇宙中最明亮的物体提供能量
power the brightest objects in the universe.
几十年来，类星体一直困扰着天文学家
奇怪的是，现在看来，即使是最明亮的天体
也仍然是不可见的
但是你知道吗？你看不到我们目前发现的最亮的星系
2015年11月2日，天文学家
利用原子大毫米波阵列“阿尔玛”(ALMA)
来观测宇宙中最亮的星系
一颗名为 w2246 的类星体
发出的光相当于350万亿个太阳的亮度
但对我们的眼睛来说，它是看不见的
因为红外线是不可见的
所以那并不是普通的星系而是“热狗星系”
“热狗”意味着模糊的星系被星际尘埃云所包围
因此来自这颗类星体的难以置信的光
被隐藏在我们的视野之外
因为就像黑洞周围徘徊并坠落物质一样
你可以想象有时候黑洞周围的物质太多了
于是类星体被完全被遮蔽起来
类星体的可见光线被厚厚的灰尘云层吸收
但能逃逸出来的是较低能量的红外线
在这个波长下，它亮度是非常惊人的
“热狗”这个的名字的确很酷，但除此之外
让人们没有想到的是
我们发现宇宙中最亮的类星体有一半是热狗
类星体非常明亮
Quasars are so bright,
有些在宇宙边缘或130亿光年之外
some are visible from the edge of the universe,
都能看到
or 13 billion light-years away.
这就意味着它们在大爆♥炸♥后不到10亿年
That means they burst into life less than a billion years
就开始生成了
after the big bang.
这样的怪物怎么会在宇宙诞生后
How could such monsters exist
这么快就存在呢？
so soon after the birth of the universe？
在整个宇宙中
Across the universe,
我们发现了令人震惊的发光类星体
we have discovered stunningly luminous quasars.
它们比它们所在的整个星系更强大，更明亮
They're powerful, brighter than their whole galaxies,
这些光已经向我们传播了
and that light has been traveling towards us
数十亿年
for billions of years.
光速，每秒186000英里
As fast as light goes, 186,000 miles per second,
它需要时间来覆盖的巨大星系之间的距离
it takes time to cover the vast distances between the galaxies,
如果你观察太空
so if you look out into space,
你看到的类星体是在数百万年前
you see quasars as they were millions of years ago
或几十亿年前
or billions of years ago,
他们发出的光今晚才刚刚到达你的眼睛
and the light has just arrived at your eyes tonight.
2017年,智利……
2017, Chile...
洛斯坎帕纳斯天文台的科学家们
Scientists at the Los Campanas observatory
将望远镜聚焦于
focus their telescopes
宇宙中最古老的地方
on the most ancient part of the universe.
他们得到了一个巨大的惊喜
They get a huge surprise.
这个类星体大约在
This quasar is only about 600,
大爆♥炸♥后的6、7亿年形成
700 million years after the big bang,
而这个黑洞的质量大约是
and this black hole weighs about 800 million times
太阳的8亿倍
as much as the sun.
它是迄今为止发现的最古老的类星体
It's the oldest quasar ever found.
它是在大爆♥炸♥后7亿年左右
It burst into life around 700 million years
开始形成的
after the big bang.
那时，宇宙基本上只是氢气和氦气的
Back then, the universe was mostly a soup of hydrogen
混合物
and helium gas.
我们知道类星体是由超大质量黑洞提供能量的
We know quasars are powered by supermassive black holes,
但在宇宙演化的早期
but discovering a black hole this big so early
发现这么大的黑洞，是一个巨大的谜团
in the evolution of the cosmos, that's a huge mystery.
天文学中的一个大问题是
One of the big questions we have in astronomy is,
这些超大质量黑洞是如何形成的？
how did these supermassive black holes form？
它们是如何在宇宙早期形成的？
How did they form so early in the universe？
这是一个有趣的谜团
This is an interesting mystery.
类星体是我们能看到的最远的天体
We see quasars about as far as we can see.
这意味着这些天体存在于最早的星系中
That means these objects existed in the very earliest galaxy.
这意味着有一百万个或十亿个太阳质量的物体
That means a million or billion solar mass objects
能够聚集在一起
were able to accumulate.
我不认为我们真的很清楚
I don't think we really have a good picture
这是如何发生的
of how that can happen.
谜团在于黑洞的增长速度
The mystery lies in how fast black holes grow.
它们以惊人的速度通过吞噬来成长
They grow by eating at an astonishing rate.
当你吃东西的时候，你总会吃饱
When you eat, eventually, you get full.
你总会有吃完最后一口的时候
You've had your last bite.
但是黑洞，它们永远不会停止饥饿
But black holes, they are never done being hungry.
它们欲壑难填
They are insatiable.
黑洞会吃掉一切靠得太近的东西
A black hole eats everything that gets too close,
然后变得越来越大
growing larger and larger.
但它们的增长速度是有限的
But there's a limit to how fast they can grow.
没有足够的时间
There's not enough time,
在宇宙诞生10亿年之后
a billion years after the universe was created,
要让它们达到10亿太阳质量……
for them to get to a billion solar masses in...
时间太短了
It's just too short a time,
所以除了吃东西，肯定还有
so there had to be another process,
其他的过程，导致它们的形成
in addition to all this eating, that caused the seed to form.
我们现在认为，这些庞然大物
To bulk up to a billion solar masses,
是由较小的种子黑洞演化而来的
we now think these giants grew from smaller seed black holes.
我们知道，黑洞通常是由大约25倍太阳质量
We know that black holes usually form from exploding stars
或更大的恒星爆♥炸♥形成的
of around 25 solar masses or more.
这是很小的黑洞
That's pretty small.
要产生超大质量的，那么就需要一颗超大质量的恒星
To be born supermassive, you'd need a supermassive star,
一颗从早期宇宙的原始气体中
a stellar giant born from the primordial gases
产生的恒星
of the early universe.
这些巨大的星云主要由氢组成
And so you had these huge clouds of mostly hydrogen,
少量的氦
a little bit of helium,
基本上就是这些了
and that's basically all that was there,
随着物质冷却
and as material cooled,
它会坍缩成这些巨大的恒星
it would collapse into these big,
一个太空中巨大的氢原子球恒星
big stars of just balls of hydrogen in space.
这些超级巨星成长得快，死亡得也早
These super-giant stars lived fast and died young.
它们死后，就形成了这些种子黑洞
When they died, they formed these seed black holes.
所以这是得到大质量“种子”的一种方法
So that's one way you could get a massive seed,
就是让最早的恒星
is that you just have the earliest stars
在死亡时坍缩成黑洞
collapsing into a black hole when they die.
但这里有个问题
But there's a problem.
似乎即使是这些超大质量的恒星也无法产生
Seems even these supermassive stars couldn't have produced
足够大的种子黑洞
big enough seed black holes.
一定有其他方法可以在不到10亿年的时间里
There has to be another way to generate a billion-solar-mass
产生一个10亿太阳质量的黑洞
black hole in less than a billion years.
否则宇宙如何能从
How else could the universe create
厚厚的气体云中
supermassive black holes
创造出超大质量的黑洞呢？
from just thick clouds of gas？
有一种理论认为超大质量黑洞
One theory of how you get these supermassive black holes
只有一次大的坍塌事件
is that you just have one big collapse event.
我们称之为直接坍缩
We call it direct collapse.
这只是一种理论
It's only a theory,
但我们认为这就是直接坍缩的原理
but we think this is how direct collapse would work.
巨大的超高密度的氢气云聚集在一起
Huge, super-dense clouds of hydrogen gas clump together.
引力逐渐增加，把更多的气体拖进来
Gravity builds up, dragging in more gas,
然后变得越来越密集
becoming more and more dense
直到气体在自身重量的作用下崩塌
until the gas collapses under its own weight.
它没有形成恒星，而是直接挤压成
Instead of forming a star, it crushes down straight
超大质量黑洞
to a supermassive black hole.
一个星系开始在这个巨大怪物周围形成
A galaxy starts to form around the giant.
气体流向中心，温度越来越高
Gas streams toward the center, getting hotter and hotter,
直到类星体爆♥炸♥的产生
until a quasar explodes into life.
它们非常明亮，我们今天都能
They're so bright, we can see them today,
在130亿光年远的地方看到它们
13 billion light-years away.
所有这些现在都只是个想法
All of these are ideas right now.
理论家们正在努力让这些模型工作
Theorists are working really hard to make these models work.
发现越来越远的类星体将告诉我们
Finding more and more distant quasars
这些形成类星体的种子是什么
will teach us what those seeds are that form into the quasars.
它可能教会我们一些新的物理知识
It might teach us some new physics
关于如何快速创建这些大黑洞
to create these big black holes that quickly.
我们对类星体研究得越多
The more we investigate the quasars,
我们对早期宇宙以及其中星系的发现也就越多
the more we discover about the early universe, and the galaxies within it.
看似平静和平的星系
Galaxies that appeared calm and peaceful places
但仔细观察后可以发现一些极端暴♥力♥和破坏