了解宇宙是如何运行的（2010）

How the Universe Works S08E07

Part 3 Jan. 30, 2022, 2:58 p.m.

in all directions,
92 billion light-years across...
……而且每秒钟都在变大
...And getting bigger
by the second.
布洛克:这个数字大得让人难以理解
Bullock: This number is
so incomprehensibly large
你的大脑很难想像出来
that it's difficult to wrap
your brain around.
在这个体积里有数万亿个星系
There are trillions of galaxies
within this volume.
这是惊人的
It's staggering.
它比我们熟悉的任何东西都要大得多
It's so much larger than
anything we're familiar with.
如果我们要去可
Narrator:
If we were to travel
观测宇宙的边缘
to the edge
of the observable universe,
我们会进入更陌生的领域
we would enter even more
unfamiliar territory.
想象一下我们在一艘超快的宇宙飞船里
Imagine we're in
an ultra-fast spaceship.
我们离开了太阳系，然后是银河系
We leave the solar system,
then the milky way.
随着我们深入星系间的空间
As we travel deeper
into intergalactic space,
事情开始变得非常奇怪
things start to get
really weird.
我们每离开银河系100万光年
For every million light-years
we go from the milky way,
星系就会以
the galaxies move away from us
每秒13英里（约21公里）的速度远离我们
at around 13 miles
per second faster.
我们必须加速才能跟上
We have to accelerate
just to keep up.
但星系一直在移♥动♥，永远超出我们的能力范围
But the galaxies keep on moving,
always beyond our reach.
♪
♪
普莱特:想象你是一名跑道上的短跑运动员
plait: Imagine you're a sprinter
on a racetrack.
如果你跑向终点线
If you're running towards
the finish line,
可能会花上几秒钟的时间
it may take you a few seconds
to cross it.
但是现在想象终点线正在远离你
But now imagine that that finish
line is moving away from you.
如果它以和你跑得一样的速度离开你
If it's moving away from you at
the same speed you're running,
你永远也到不了它
you'll never reach it.
如果它离开得比跑步者还快
And if it's moving faster
than the runner,
那么再快的跑步者也达不到它
then even faster runners
won't reach it.
这就是我们在这里看到的宇宙
And that's sort of what we're
seeing here with the universe.
在一定距离之外
Narrator:
Beyond a certain distance,
星系正在以比光速还快的速度远离我们
galaxies are racing away from us
faster than the speed of light.
这条线叫做宇宙视界
It's a line called
the cosmic event horizon.
我们在可观测宇宙中看到的97%的星系
And 97% of galaxies we see
in the observable universe
都在这条线之外，无法到达
are beyond this line
and unreachable,
包括 gn-z11
including gn-z11.
他们好像在取笑我们说，“看看我”
They're sort of teasing us
to say, "look at me,
“多好的一块房♥地♥产♥啊”
what a nice piece
of real estate."
但我们知道，即使我们现在开始去那里
but we know even if we started
going there now,
我们也永远无法到达那里
we could never reach them.
任何跨越宇宙视界的东西
Narrator: Anything that has
crossed the cosmic event horizon
都是我们永远无法触及到的
is out of our reach forever.
但这还不是全貌
But that's not the full picture
因为宇宙的膨胀率在变化
because the expansion rate
of the universe is changing.
20多年前，天文学家发现
A little over 20 years ago,
astronomers discovered
目前宇宙膨胀的速度
that the current rate
of the universe's expansion
正在加速，它竟然在加速
is accelerating,
it's speeding up.
天文学家怀疑有一种神秘的力量在起作用——
Narrator: Astronomers suspect
a mysterious force is at work --
暗能量
dark energy.
我们认为是暗能量将宇宙推开
Dark energy is what we think
is pushing the universe apart,
是它导致宇宙加速膨胀
causing this
accelerating expansion.
而暗能量的起源和真正的物理性质
And the origin and true
physical nature of dark energy
是一个巨大的谜
is a big mystery.
拜暗能量所赐，越来越多的星系
Narrator: Thanks to dark energy,
more and more galaxies
穿过了宇宙视界
are crossing
the cosmic event horizon
离开了可观测的宇宙
and leaving
the observable universe.
这些星系……
These galaxies...
我们永远失去了
Are lost to us forever.
普雷特:我们今天可以看到的一些星系
Plait: There are galaxies
that we can see today
在几百万年后，我们就看不到了
that in a few million years,
say, we won't be able to see
因为可观测宇宙的边缘
because the edge of
the observable universe
基本上比那个星系更近了
has basically moved in closer
than that galaxy.
这是常有的事
That's going to happen
all the time.
一万亿年后
And in a trillion years
or something like that,
我们在天空中看到的所有星系
all these galaxies
that we see in our sky
都将完全看不见
will be completely invisible
因为它们都将在可观测宇宙的边缘之外
because they'll be beyond
the edge of the universe.
泰勒:所以最终，每一个星系
Thaller: So eventually,
every last galaxy
都将离我们非常遥远
will be so far away from us
以至于光无法通过不断膨胀的空间到达我们
that light cannot reach us
through that expanding space.
这就好像你开着车穿过一片黑暗的沙漠
It's almost as if you're driving
through a dark desert
最后一个曾经存在的城镇
in your car
and the very, very last town
已经消失在地平线上
that ever exists
has gone over the horizon
它们再也不会有亮光了
and they'll never be
any light again.
随着我们进入未来
We can see less
and less of the universe
我们看到的宇宙越来越少
as we go into the future.
多么奇怪的想法
What a strange thought.
这意味着我们现在应该尽我们所能建造望远镜
So that means we should build
all the telescopes we can now.
即使是用最先进的望远镜
Narrator: There's a limit
to the universe we can see,
我们能看到的宇宙也是有限的
even with the most
advanced telescopes.
但在宇宙视界之外
But what lies beyond
是天文学中最大的谜团之一
is one of the biggest
mysteries in astronomy.
更大的宇宙可能比我们
The greater universe
could be stranger
最疯狂的想象还要陌生
than our wildest imagination.
普里特:当你站在海滩上
Plait:
When you stand on the beach
看着地平线
and you look at the horizon
你会想，“哦，地平线之外”
and you kind of think,
"oh, what beautiful lands
“有什么美丽的土地？”
are there beyond the horizon?
“我以前从来没有想过”
Things I've never
imagined before."
它是如此的自然
it's so natural.
人们会问，“在那后面是什么？”
It's so human to ask,
"what lies beyond that?
宇宙的真正范围是什么？”
What is the true extent
of the universe?"
♪
可观测的宇宙
narrator:
The observable universe
包含了数万亿个星系
contains trillions of galaxies.
它大约有920亿光年宽……
It's about 92 billion
light-years across...