了解宇宙是如何运行的（2010）

How the Universe Works S01E05

Part 5 April 18, 2021, 7:56 p.m.

巨型中微子探测器
buried deep underground.
我们看到有辐射穿过中微子探测器
And bingo, we saw a burst of radiation
go through our neutrino detectors
我们说: 这就是证据
and we said, "Ah-ha, That's the proof."
发现来自超新星1987A的中微子
The discovery of neutrinos
from Supernova 1987A
是意义重大的事
was a tremendous thing
因为多年来人们一直说
because, for many years,
people had been saying,
其余99%的爆♥炸♥能量存在于中微子
"That's where 99 percent
of the energy goes.
但没有人看到过它
But no one had ever seen it."
现在证据确凿, 我们能够证明
This is now the smoking
gun that we can now prove
中微子携带了超新星的能量
that neutrinos carry the
energy of a supernova.
我们在外层空间观测到超新星的同时
And we detected it right on the Earth
在地球上探测到了中微子
as we saw a supernova in outer space.
中微子比原子小几万亿倍
Neutrinos are trillions of
times smaller than atoms.
从核电站到核弹再到恒星爆♥炸♥
They're created by all
sorts of nuclear reactions...
所有类型的核反应都能产生中微子
from nuclear power plants
and bombs to exploding stars.
若你能看见中微子, 它们无处不在
If you had neutrino vision,
you'd see them everywhere.
中微子是像幽灵一样的粒子
Neutrinos are ghost-like particles.
就在我们讲话时
Literally trillions of them
are going through my body
数万亿中微子穿过我们身体
even as we speak.
其实中微子来自于地下
In fact, neutrinos come from the bottom
of the floor right through the Earth
也许正穿透我的双腿
and even hit me right through my legs.
真奇异
Pretty strange.
如此多微粒快速通过我们身体
Imagine so many tiny particles
zooming through our bodies.
但它们的能量从哪里来呢?
But where do they get all their energy?
当超新星的内核在爆♥炸♥前压缩时
When a core crushes down just
before a supernova explosion,
里面的原子发生分♥裂♥
the atoms inside it are broken up.
内核热力将原子碎片聚变成中微子
The core gets so hot, it turns this
atomic debris into blazing neutrinos.
当恒星内核塌缩成中子星时
We think that supernovae produce
a stupendous sum of neutrinos
超新星产生了大量中微子
when the core collapses
to a neutron star.
有约10秒时间
For about 10 seconds,
内核以中微子光度发光
that core... shines with
a neutrino luminosity...
这比那一刻宇宙其它地方产生的…
that is greater... than all
of the energy being produced
所有能量都要大
in the rest of the
universe at that time.
换言之, 它极其光亮
In other words, it's really bright.
但引力无法将这些中微子留在内核
But gravity can't hold
these neutrinos in the core.
它们喷发出来和迸发耀眼光芒
They burst free in a
blinding flash of light
将垂死恒星撕得粉碎
that rips the dying star apart.
中微子的发现改变了超新星的知识
The discovery of neutrinos
transformed the science of supernovas.
但超新星即将揭示最神秘的力量
But supernovas were about to reveal
the most mysterious force of all,
一种正在改变宇宙命运的力量
one that's changing the
destiny of the universe.
超新星爆♥炸♥如此耀眼
Supernova explosions are so bright,
整个宇宙都能看到
we can see them across
the entire universe.
天文学家利用它揭开了
This has helped astronomers unlock
宇宙中最神秘的谜团之一
one of the deepest
mysteries of the cosmos.
宇宙在140亿年前大爆♥炸♥中诞生
The universe came to life in the
big bang 14 billion years ago.
由一个比原子还小的极微小能量点
It expanded from a tiny ball
of energy smaller than an atom
膨胀形成横跨亿万光年的宇宙
to a universe billions and
billions of light-years across.
而且它仍在不断膨胀
And it's still expanding.
我经常想未来的人
I've often wondered
how far future people
会对宇宙大爆♥炸♥知道多少
will even know the big bang happened...
因为我们知道大爆♥炸♥发生
because we know the big bang happened
是来自看到所有星系飞离我们
from watching all the
galaxies fly away from us.
总有一天星系的距离会远到
Someday, the galaxies will be
so far away from each other...
天空变成甚么也看不见
it will be impossible to
see anything else in the sky.
科学家以前认为
Scientists used to think
宇宙膨胀速度正在减慢
the expanding universe was slowing down,
但没有办法证明这点
but there was no way to prove it
直到发现了la型双子超新星
until they found double
star supernovas, Type la's.
当白矮星的质量
They always explode
达到太阳的1.4倍时就会爆♥炸♥
when the white dwarf star reaches
exactly 1.4 times the mass of our sun.
爆♥炸♥通常会释放出等量的光
And their explosions always release
exactly the same amount of light.
它们是测量太空距离的完美标记
They are the perfect markers
to measire distance in space.
la型超新星
Type la supernovae,
若我们知道它们的实际亮度
when we know how bright they are
和它们的观测亮度
and how bright they look,
就能测出它们的距离
we can tell the distance...
因为距离越远
because the farther away they are,
在望远镜中看上去就越暗
the less bright they'll
look in a telescope.
这能帮助我们准确地测量距离
And that has allowed us to
accurately measure distances...
不仅能测出附近星系的距离
not just to nearby galaxies,
还可以测量到宇宙另一端
but to galaxies at the other
end of the visible universe.
数十亿光年之外的星系的距离
billions of light-years.
这给我们带来了许多骜人发现
And that has allowed us to
make incredible discoveries.
天文学家以为找到了方法去证明
Astronomers thought they
had found a way to prove
宇宙膨胀速度正在减慢
the expansion rate of the
universe was slowing down.
但事实却出人意料
What they got was a big surprise.
1998年天文学家有个惊人发现
In 1998, astronomers made a
remarkable and unexpected discovery.
原本认为在引力作用下
It was recognised that the universe,
which should be slowing down
宇宙膨胀速度正在减慢
because gravity, after
all, is attractive,
而且物体的质量
and the mass of objects
应该令宇宙膨胀速度减慢
should cause the expansion of
the universe to slow down...
但膨胀实际上在加速
but the expansion is speeding
up, it's accelerating.
来自la型超新星的持续光线
The constant light
from Type la supernovas
完全改变了天文学家对宇宙的理解
completely changed the way
astronomers understand the universe.
每一本科学教科书都指出
Every science textbook on the Earth says
宇宙在膨胀和膨胀在减慢
that the universe is
expanding and slowing down.
大错特错
Wrong.
我们现在必须改写
We now have to rewrite
所有科学教科书
all the science textbooks
on the planet Earth.
但天文学家仍然不明白
But astronomers still didn't know why
为何宇宙会膨胀得越来越快
the universe is expanding
faster and faster.
他们开始认为有一种未知的能量
They began to think it's
some kind of unknown energy.
他们称之为暗能量
They called it dark energy.
但很难证明它的存在
But it's difficult to prove
因为它见不到, 摸不到, 探测不到
because it can't be seen
or touched or detected.
我们对暗能量的物理性质和起源
We really don't have a very good clue
知道得非常少
as to the physical nature
and origin of dark energy.
或许目前所有物理问题中
It's perhaps the number one...
最值得观测研究的
observational ly-motivated problem
in all of physics right now,
就是暗能量的性质
the nature of the dark energy.
从暗能量到黑洞, 超新星解答了
From dark energy to black