了解宇宙是如何运行的（2010）

How the Universe Works S06E01

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

这些x射线可以用来追踪轨道
and those x-rays can be used,
then, to trace out the orbits
从而提取质量
and, therefore,
extract the mass.
当科学家们计算出
When scientists work out
这两个物体的大小和质量时
the size and mass
of the two objects,
他们发现第一个是一颗类日恒星的
they find the first
is the fading corpse
褪色尸体
of a sunlike star.
而第二个物体虽然很瘦
And while the second object
is tiny,
却有一个庞然大物的质量
it has the mass of a giant.
难道这就是一个难以捉摸的黑洞吗？
Is this an elusive black hole?
我们这里讨论的是一个质量非常大
What we're talking about here
is an object
体积非常小，密度非常大
that is very massive,
very small, very dense,
并且引力非常强的物体
with intense gravity.
当然还在其他很多不同的途径
But it turns out there
are lots of different ways
来创建这样的物体
to create an object like that.
比如宇宙中还有另一种超密度物体
There is another type of
ultra-dense object out there
叫做中子星
in the universe,
called a neutron star.
中子星的形成方式与我们认为的黑洞的形成方式相同
Neutron stars form in the same
way we think black holes form...
当恒星死亡，爆♥炸♥
When stars die, explode,
然后塌缩成一个微小的物质球
but then collapse down
into a tiny ball of matter.
中子星的引力是巨大的
The gravitational attraction
of a neutron star is enormous,
能吸引气体、尘埃和小行星
pulling in gas,
dust, and asteroids.
但是光仍然可以逃逸
But light can still escape.
黑洞和中子星是近亲
Black holes and neutron stars
are kind of cousins,
但中子星的质量
but in the case
of a neutron star,
还不足以崩溃失控
it didn't have quite enough mass
to collapse out of control.
所以你可以把它想象成
So you can sort of think of it
as just barely hanging back
失败的黑洞
from collapsing
into a black hole.
区分中子星和黑洞的区别很容易
中子星有一个表面
你可以看到它发出的光
如果有什么东西掉下来，就会掉到表面上
而黑洞没有表面
中子星的表面是一个你不想去的地方
微小的物体但有巨大质量，意味着它的引力非常巨大
它会在瞬间压碎一个人
但是中子星的质量仍然比黑洞的质量小
它们的质量是有上限的
质量不到太阳的三倍
它们不能再变大了
因为那样它们就会坍塌形成一个黑洞
所以如果我们看到一个没有发光的物体
质量是太阳的三倍以上
它就不可能是中子星
核光谱望远镜阵列发现的微小物体
The tiny object
discovered by NuSTAR
确实有巨大的质量
does have enormous mass.
但仅凭大小和质量
But size and mass alone
还不足以证明它是一个黑洞
are not enough to prove
it's a black hole.
宇宙学家需要更多的证据
Cosmologists need more evidence.
他们看不见黑洞，但有没有其他方法呢？
They can't see black holes,
but is there another way?
如果他们能听到他们的声音呢？
What if they could hear them?
几乎所有的天文学都是以电磁频谱为基础的
可见光，x射线，无线电波等
而引力波却是完全是另一回事
它们是由我们宇宙中一些最奇异的事件中产生的
所以它们让我们直接听到了那些我们根本看不到的事件
尽管完全看不见，但我们可以通过引力波听到
引力波为我们研究宇宙打了奇妙的窗口
想象一下两辆大型汽车相撞……嘣！
Think of two massive cars
colliding... boom!
当碰撞发生时，它们会发出声音
When they do,
they radiate sound,
这样我们就能知道碰撞是否发生过
and then we can tell whether
or not that collision occurred
甚至知道它离我们有多远
and maybe even
how far away it was.
黑洞碰撞也像这个一样
It's like that when
black holes collide.
所以，通过监听黑洞的碰撞……
So, by listening for
a black hole crash...
科学家们能最终证明它们的存在吗？
could scientists conclusively
prove they exist?
黑洞是宇宙中的引力巨人
Black holes are gravitational
giants of the universe.
但我们只找到了间接证据
But we've found only
circumstantial evidence
证明它们的存在
that they exist.
为了找到直接的证据
To make it a slam dunk,
宇宙学家们正在寻找
cosmologists are
listening for proof
隐匿世界中引力波存在的证据
in the hidden world
of gravitational waves.
引力波一直在这个房♥间里
There are gravitational waves
going through this room
传播
all the time.
每次像我刚才那样移♥动♥我的手
Every time I move my hands
like I just did,
我就会产生引力波
I create gravitational waves.
可问题是，引力太弱了
The problem is,
gravity is so weak
你无法探测到引力波
that you don't detect
those gravitational waves.
为了探测这些空间和时间的扰动
In order to detect those
disturbances of space and time,
必须要有大质量物体的
you have to have
cataclysmic events
灾难性事件
involving massive objects.
黑洞是宇宙中密度最大的物体之一
Black holes are some of the
densest objects in the universe.
所以我们应该能够听到并能探测到
So we should be able to hear
and measure the waves
它们碰撞时产生的引力波
created when they collide.
激光干涉引力波天文台(LIGO)
LIGO, the laser interferometer
gravitational-wave observatory,
可以监听来自
listens for waves that can come
10亿光年之外的引力波
from over a billion
light-years away.
2017年，LIGO听到了巨大的碰撞声
In 2017, LIGO heard
an enormous crash.
两个巨大的物体
Two very massive objects
以接近光速的速度相撞
collided at near
the speed of light
这让我们见证了历史上
in one of the most
energetic events
最剧烈的事件之一
that we've ever witnessed
in the history of humankind.
两个超重、超密度的物体互相旋转
Two ultra-heavy, ultra-dense
objects whirl around each other,
向太空中抛出强大的引力波
hurling powerful gravitational
waves through space.
它们彼此离得越近
The closer they fall
toward each other,
抛出的引力能就越多
the more gravitational energy
they throw out.
最后，它们相撞了
Finally, they collide,
这是宇宙中最剧烈的事件之一
in one of the most violent
events in the universe.
撞击会释放出巨大的引力波
The smash sends out
immense gravitational waves
在星系间的空间里荡漾
that ripple
across intergalactic space,
直到最终被LIGO探测到
until, eventually,
LIGO detects them.
听引力波
Listening to
a gravitational wave
就像听乐器一样
is like listening
to a musical instrument.
如果它发出特定的音调或振动
If it's making certain tones
or certain vibrations,
你就能知道乐器的大小
you can figure out the size
of the musical instrument,
乐器的类型
the type of
the musical instrument,
以及演奏乐器的人
who's playing
the musical instrument.
LIGO探测的惊人之处在于
The thing that's really amazing
about the LIGO detection
它让我们能够测量这些物体的质量
is it allowed us to measure
the mass of these objects
以及它们结合的速度
and how quickly
they coalesce together.
所以我们知道它们的密度有多大
So we actually have an idea
how dense they must have been,