了解宇宙是如何运行的（2010）

How the Universe Works S08E07

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

We can think
of the observable universe
想象成一个聚光灯
sort of like a spotlight
从你所站的地方为中心向四周照射
centered on wherever
you're standing right now
你只能看到聚光灯的边缘而不能看到更远的地方
and you can see to the edge of
your spotlight and not beyond.
但如果稍微往左移一点
But if you move a little bit
to the left,
或右移一点
a little bit to the right,
可观测宇宙会随你移♥动♥
your observable universe
actually moves with you.
对于生活在 gn-z11 星系的人来说
Narrator: For someone living
in galaxy gn-z11,
可以观测到宇宙中完全不同的部分
a totally different part of the
universe would be observable.
这个遥远的星系在我们可观测宇宙的边缘
So that distant galaxy is at the
edge of our observable universe,
我们也在他们可观测宇宙的边缘
and we are at the edge
of their observable universe.
我们有不同的聚光灯
We have different spotlights.
有一件奇妙的事情值得思考
One of the wonderful things
to think about
那就是在其他星系周围还有其他的天体
is that there are other spheres
around other galaxies,
可能还有其他的外星人，他们也在仰望着天空
there are other aliens
looking up into the sky tonight
想知道宇宙的真实范围是什么
wondering what the true
extent of the universe is.
我们宇宙的真正范围
Narrator: The true extent
of our universe
并没有以星系 gn-z11 结束
doesn't end with galaxy gn-z11.
但当天文学家使用哈勃太空望远镜
But when astronomers use
the hubble space telescope
精确测量 gn-z11 的距离时
to accurately measure
the distance to gn-z11,
他们发现了令人震惊的事情
they find something shocking.
它距离地球有320亿光年
It's 32 billion
light-years away,
比想象的要远三倍
three times further
than thought possible.
普雷特:如果没有东西能比光速更快
Plait: So if nothing can travel
faster than light
我们测量到这个星系的距离
and we measure the distance
to this galaxy,
它怎么可能在320亿光年之外呢？
how can it be
32 billion light-years away?
在宇宙的历史上
Narrator:
There hasn't been enough time
没有足够的时间
in the history of the universe
让 gn-z11 的光到达我们
for light from gn-z11
to reach us.
这里一定有什么误会对吗？
There must be some mistake here.
Right?
在这个时候
Plait: At this point,
your brain
你的大脑一定会想跳出你的头骨
is probably thinking
of leaping out
然后四处尖叫
of your skull
and running around screaming.
相信我，我知道我是一个天文学家
Trust me, I know.
I'm an astronomer.
我这辈子都在研究这个
I've been doing this
my whole life,
这些东西扭曲了我的想象力
and this stuff twists
my imagination up.
这真的很难理解
It's really hard to grasp this.
我们如何才能看到一个距离我们320亿光年
How do we see a galaxy that's
32 billion light-years away
但只有134亿年历史的星系？
and only 13.4 billion years old?
Gn-z11 之所以比它应该的距离更远
Narrator: Gn-z11 is further away
than it should be
是因为我们的宇宙发生了一些奇怪的事情
because something strange
is going on with our universe.
宇宙膨胀
It's expanding.
如果宇宙在膨胀
And if the universe
is expanding,
那么它的边缘在哪里
then where does its edge lie
我们能到达那里吗？
and can we ever reach it?
♪
138亿年前
narrator:
13.8 billion years ago,
一股能量迸发出生命
a speck of energy
burst into life.
我们称之为大爆♥炸♥——
We call it the big bang --
空间和时间被向四面八方推开
space and time
pushed out in all directions.
从那以后，我们的宇宙一直在膨胀
Ever since, our universe
has expanded.
但它的扩张方式使寻找宇宙边缘
But the way it's expanding
makes finding an edge
成为一个重大挑战
a major challenge.
宇宙在不断膨胀
The universe is expanding
并根据一个非常简单的定律膨胀
and expands according
to a very simple law
星系离我们越远
that the farther away a galaxy
is from us,
它离开我们的速度也越快
the faster it appears
to be receding away from us.
最远的星系在高速移♥动♥
Narrator: The furthest galaxies
are moving at very high speeds.
我们发现的最遥远的星系，gn-z11
The most distant galaxy
we've ever spotted, gn-z11,
似乎在短短134亿年的时间里
seems to have moved 32 billion
light-years away from us
就移♥动♥了320亿光年
in just 13.4 billion years.
这比光速还快
That's faster than
the speed of light.
我们可以测量星系
We can measure the speeds
with which galaxies
远离我们的速度
are moving away from us,
很多很多星系都在以
and many, many galaxies
are moving away from us
比光速还快的速度远离我们
at speeds faster
than the speed of light.
这听起来是违背常理的，对吧？
This sounds like
it's breaking the law, right?
有这样一种观点，你们都知道
There's this idea
that you've all been told
相对论说没有什么
that relativity
says nothing goes faster
比光速更快
than the speed of light.
好吧，你被骗了
Okay, you've been lied to.
普莱特:太空本身可以做它想做的事
Plait: Space itself can do
what it wants.
它制定规则，也可以打破规则
It makes the rules,
it can break the rules.
这一规则适用于物质，而不是空间本身
That rule applies to matter,
not to space itself.
空间可以以任何它想要的速度膨胀
Space can expand
at whatever rate it wants.
理解膨胀定律的简单方法是
Simple way to think of this
expansion law is imagine
想象你站在一块无限延伸的橡胶板上
standing on
an infinite rubber sheet
一直延伸到很远的地方
that stretches all the way out
into the distance
但你一直站在同一个地方
and you're standing
on the same place.
你可以在上面标个“X”
You can mark it
with a little "x."
现在，这块橡胶板向各个方向延展
now, all the sheet expands
in every direction.
如果它延展速度为2倍
So if it expands
by a factor of two,
假设有一个星系，在离你1英尺的距离
another galaxy that was, say,
one foot away from you
现在变成了2英尺
is now two feet away from you
as we stretch the sheet,
而另一个星系离你10英尺远
but another galaxy
was 10 feet away from you.
把它扩大2倍
Expand that by a factor of 2
它就离你20英尺远了
and now
it's 20 feet away from you.
所以在相同的时间内，一个星系移♥动♥了1英尺
So in the same amount of time,
one galaxy moved one foot,
而另一个星系移♥动♥了10英尺
where another galaxy
moved 10 feet.
所以装填物质越多
So the more stuff there is,
你和另一个星系之间的弹性就越大
the more elastic
between you and another galaxy,
它似乎就越远离你
the more it seems
to expand away from you.
膨胀意味着我们的可观测宇宙
Narrator: Expansion means
our observable universe
向各个方向延伸了460亿光年
stretches for a colossal
46 billion light-years
横跨920亿光年