了解宇宙是如何运行的（2010）

How the Universe Works S01E05

Part 4 April 18, 2021, 7:56 p.m.

每秒100万个地球令黑洞难以消化
A million Earth masses a second is too much
for the black hole to consume all at once.
所以它以接近光速将很多物质吐出
So it spits a lot of it back
out at nearly the speed of light
形成两股能量束从黑洞喷射出来
This creates two beams of pure energy
blasting their way out of the black hole.
穿透恒星只需八秒
It takes it about eight seconds
to bore through the star,
非常集中, 从表面喷发出来
keeping a very tight focus,
and erupt from the surface.
若站在喷射口, 会看到伽玛射线暴
Now, if we're standing in the opening
of this jet, we'll see a gamma-ray burst.
产生于黑洞的伽玛射线
The gamma rays produced
from the black hole
冲破恒星外层飞入太空
tear through the outer layers
of the star and into space.
伽玛射线暴是我们所知的
Gamma-ray bursts are
the most violent event...
宇宙中最猛烈的活动
that we know of in the universe.
巨星爆♥炸♥后形成黑洞
A giant star blows itself to
pieces and forms a black hole.
场面极其壮观
It's incredibly spectacular.
这些伽玛射线暴能量巨大
These gamma-ray bursts
are so energetic,
它们可以照亮整个宇宙
they light up the entire universe.
宇宙中的任何地方
Any point in the universe
最终都会接收到
will eventually pick up
this astounding radiation
来自伽玛射线暴的辐射
coming from a gamma-ray burst
可见它们的能量有多高
That's how energetic they are.
它们是已知宇宙中最亮物体
They are the brightest
things in the known universe.
一个典型超新星爆♥炸♥产生的能量
To put things in perspective,
a typical supernova explosion

等于太阳１００亿年寿命的能量总和
is about what the sun will put out in
its entire 10-billion-year lifetime.

而正在喷射的伽玛射线暴
A gamma-ray burst
viewed jet-on
比超新星还要亮1亿倍
is a hundred million times
more luminous than a supernova.
它们无疑是宇宙中最亮的东西
They're the champions
for brightness, for sure.
它们不仅亮, 而且破坏力极大
They're not only bright, they're letha
若伽玛射线暴击中地球
If a gamma-ray burst
were to hit the Earth,
会在数秒内毁掉大部分大气层
it would destroy most of
the atmosphere in seconds.
伽玛射线暴就像步♥枪♥射击
A gamma-ray burster
is like a riffle shot.
若你在瞄准在线, 当心
And if you're in the
line of sight, watch out.
一旦被辐射击中
Once the radiation hits you,
地球表面将会被一氧化氮笼罩
it will bathe the entire surface
of the Earth with nitric oxides
臭氧层将荡然无存
which will wipe out the ozone layer.
炙热辐射将摧毁植物和藻类
Blistering radiation would
hit plant life, hit algae,
整个食物链将会崩溃
the whole food chain would collapse.
若射线暴够接近
If the burst was close enough,
会引起大规模生物灭绝
it would cause mass extinctions.
伽玛射线暴…
Gamma-ray bursts turn out
to be a lot more common
远比我们想象的常见
than we thought they would be.
很可能有些曾袭击过地球
So it's possible that some of these
have even hit the Earth in the past.
那是很可怕, 可能已发生过
That's a pretty scary scenario,
it may already have happened.
问题是若它发生过, 会再发生吗?
The question is if it happened
before, could it happen again?
伽玛射线暴像打了类固醇的超新星
A gamma-ray burster is basically
a supernova on steroids.
只需要一颗巨星爆♥炸♥死亡
You need a giant star to die violently.
离我们最近而有可能发生这种事的
Now, the nearest star
to us that might do that
就是海山二
is Eta Carinae.
这是壮丽的星云
And it's a spectacular nebula.
各种物质正在从这颗恒星中喷出
There's all kinds of
material flying off this star.
它极不稳定
It's very unstable.
很可能已放射过伽玛射线暴
It may already have exploded
in a gamma-ray burst.
但海山二可能并不是唯一的威胁
But Eta Carinae may
not be the only threat.
还有其它垂死的恒星
There are other dying stars out there.
其中一个正指向地球方向
Believe it or not, one of them
is pointed in our direction.
我们正盯着WR 104的炮筒
We are staring down the
gun barrel of WR 104,
这双星总有一天会爆发伽玛射线暴
two dying stars that will one
day undergo a gamma-ray burst.
问题不是会不会, 而是几时
Not a question of if.
A question of when.
WR 104的袭击名单中也许有地球
That WR 104 may have our name on i t.
但好消息是
But the good news is...
我们可能不会预先知道
we probably wouldn't
know about it in advance.
我们还没来得及反应就已被击中了
The shock would hit us before
we had a chance to do anything.
所以担心是没用的
So there's no sense
worrying about it, anyway.
事实上我们永远不会知道一颗恒星
The truth is we'll never know if a star
是否即将变成超新星和爆♥炸♥
is about to go hypernova and explode.
等看到它爆♥炸♥时, 已为时晚矣
Anyway, by the time we see it,
it will already be too late.
其实我们时刻暴露在
In fact, we're already exposed to rays
濒死恒星放出的辐射中
from dying stars every
second of every day.
当巨星爆♥炸♥
When giant stars explode...
那是宇宙中最猛烈的爆♥炸♥
they make the biggest
bangs in the universe.
是甚么赋予它们如此巨大威力?
But what gives them so much punch?
直至最近才揭开这谜团
Until recently, no one knew.
当科学家想在计算机仿真超新星爆♥炸♥
Scientists, when they tried to simulate
a supernova explosion in a computer,
他们遇到了难题
had a problem.
他们无法从垂死恒星获取足够能量
They simply could not
get enough energy...
形成超新星
out of the dying star
to create a supernova.
这是天文学的灾难
This was a calamity in astronomy.
计算机模型无法仿真恒星爆♥炸♥
Computer models couldn't make
the simulated stars blow up.
要使恒星爆♥炸♥, 需要巨大能量
To blow up a star, you
need a lot of energy.
问题是天文学家无法找到这种能量
The trouble was astronomers
coulckn't find it
可见的辐射是释放的总能量中
The visible radiation
that you see is a tiny
极其微小部分
fraction of the total energy emitted.
即使气体膨胀产生的动能
Even the energy of motion...
of the expanding gases
也仅占总能量的
is only one percent of the total energy.
其余的99%能量在哪里呢?
Where was the missing 99 percent
of the energy from the explosion?
要使模拟脗合真实情况的唯一方法
The only way scientists could get their
simulations to match the real thing
就是加入一种神秘粒子, 叫中微子
was to add in a mysterious
particle called the neutrino.
没中微子, 数字加起来与总数不符
Without it, their numbers didn't add up.
这是容易的部分
That was the easy bit
下一步是证明超新星产生中微子
Their next step was to prove
supernovas really do produce neutrinos.
1987年, 他们获得好运
In 1987, they got lucky.
16.8万年前一颗超新星
168,000 years ago, a supernova
exploded in a nearby galaxy
在接近的大麦哲伦星云爆♥炸♥
called the Large Magellanic Cloud.
当科学家们看到来自爆♥炸♥的光线时
When scientists saw the
light from the blast,
他们将它命名为超新星1987
they called it Supernova 1987.
超新星1987A对于超新星研究
Supernova 1987A is really important...
十分重要
in the study of supernovae
因为这是自望远镜发明以来
because its the first one
我们发现的第一颗超新星
since the invention of the telescope.
我们利用现有的一切工具
It's the one that we've been able to study
right from the time of explosion through now
研究它从爆♥炸♥至今的全过程
using all the instruments
that we've developed.
其中一种工具就是深埋地下的
One of those instruments
was a giant neutrino detector