了解宇宙是如何运行的（2010）

How the Universe Works S05E01

Part 2 April 18, 2021, 7:46 p.m.

这东西有所谓的角动量
This stuff has what's called angular momentum.
角动量是
Angular momentum is the force of rotation
使气体云围绕恒星中心旋转的
that keeps the clouds of gas spinning around the center
自转离心力
of the forming star.
它的工作原理
It works against gravity,
是阻止重力并把气体变成一个薄圆盘
smearing the gas into a thin disk.
年轻恒星或原恒星
Young stars, or protostars,
只有在中心气体云达到超热稠密状态时
can only ignite if the central gas cloud
才会引爆核聚变
reaches a super hot, dense state.
但是圆盘绕着中心旋转的太快了
But the disk spins around the center too fast
重力无法起作用
for gravity to do its work.
科学家们现在明白
Scientists now understand that a third force
有第三种力量在起作用
is at at play here.
这就是磁力可以发挥作用的地方
That's where magnetism can play a role.
原恒星也就是正在形成的恒星的磁性
The magnetism of the protostar, the forming star,
实际上可以影响圆盘，减慢圆盘的速度
can actually affect the disk and slow it down
让圆盘的旋转速度下降，并帮助恒星自身的形成
and actually let it drop in and help the star itself form.
正在形成的恒星
The swirling gas in the forming star
及其周围圆盘中的漩涡气体
and its surrounding disk
产生了强大的磁场
generate powerful magnetic fields.
这些磁场抓住快速移♥动♥的粒子
These fields grab the fast-moving particles,
使它们减速
slowing them down.
布洛克:磁力就像宇宙制动器一样
Bullock: Magnetism works like a cosmic brake.
不断地一点点减速
It slows down a little bit
最终使漩涡气体螺旋进入中心
and eventually spirals into the center.
重力赢了
Gravity stars to win.
引力超过了角动量
Gravity beats out that angular momentum,
恒星就形成了
and star formation happens.
引力将正在减速的圆盘向内拖曳
Gravity drags the slowing disk inwards,
直到气体密度达到点燃的程度
crushing it until the gas gets so dense it ignites.
一颗恒星爆发了生命
A star bursts into life.
这是我们120亿年前的宇宙
This is our universe as it looked 12 billion years ago.
由于重力和磁力的挤压
The gassy cosmos is filled with flashes
不断使得氢气体云产生恒星
as gravity and magnetism crush clouds of hydrogen gas
气态宇宙充满了闪光
to create stars.
其中一些最大的恒星
Some of the largest of these stars burn through
会迅速燃烧掉它们的氢燃料
their hydrogen fuel quickly.
没有聚变的力量
Without the power of fusion,
就没有什么能与引力抗衡
there's nothing to fight against gravity.
有时，当恒星坍缩和内爆形成超新星时
Sometimes this leads to a violent, magnetic death
这会导致剧烈的磁死亡
when the star collapses and implodes in a supernova.
恒星的外层气体被吹向太空
The gassy outer layers of the star blow out into space,
而恒星的核心向内挤压
and the core of the star crushes inward,
增强了其磁性
supercharging its magnetism.
如果你观察恒星
If you look at stars, just about all stars have
几乎所有的恒星表面都有很强的磁场
strong magnetic fields at their surface.
显而易见的是，如果一颗恒星死亡并坍缩
What happens is that if a star dies and it collapses,
那么同样大小的磁场一定仍然存在
the same amount of magnetic field must still be present.
因此，如果恒星的表面♥积♥减少了1000或1♥0♥0♥0♥0♥倍
So if the surface area of the star is decreased
那就意味着
by a factor of 1,000 or 10,000,
磁场强度
then that means that the magnetic field intensity
必须增加相同的量
must increase by that same amount.
随着超新星的核心坍塌
As the supernova's core collapses,
磁场的强度不断增强
the magnetic field's strength keeps building.
最后，你会得到一个12英里宽的球体
At the end of all this, you get a ball 12 miles wide
叫做磁星
called a magnetar.
这些高密度的球体有非常非常强的磁场
These dense balls have very, very strong magnetic fields.
事实上，它们是宇宙中最强的磁场
In fact, the strongest magnetic fields in the universe.
磁场可以比地球磁场
The magnetic field can be more than a trillion times
强一万亿倍以上
stronger than the earth's field.
如果你非常非常接近一个磁星
If you got very, very close to a magnetar,
那么强的磁场可能会把你撕裂
that strong magnetic field might possibly rip you apart
因为你的原子无法在这么强的磁场附近
because your atoms just can't stay together
保持在一起
in the vicinity of such a strong magnetic field.
具有形成磁星潜力的巨恒星
Giant stars with the potential to form magnetars
仍然存在于我们的宇宙中
still exist within our universe.
科学家们知道在我们的星系中有23颗磁星
Scientists know of 23 magnetars within our galaxy today,
其中一颗，sgr 1806-20
and one of these, sgr 1806-20,
距离地球5万光年
located 50,000 light-years from earth,
这就是2004年
is the same magnetic monster that unleashed an assault
对地球发起攻击的磁怪物
on the earth in 2004.
爆♥炸♥是由星震引起的
The blast was triggered by a starquake.
这就像地震
That's like an earthquake, but it's on a star,
但它发生在一颗磁星上
and the crust of the star slipped about this much,
而磁星的地壳上
literally about a centimeter,
只是滑动了大约一厘米
the width of your finger, but this was far larger
相当于你手指的宽度
than any earthquake this planet has ever seen,
但这远远大于这个星球所见过的
millions of times stronger,
任何地震的数百万倍的强度
and the magnetic field is coupled with the matter in it.
所以当磁星地壳滑动时
So when the crust slipped, so did the magnetic field,
磁场也在滑动，它发射了一股能量巨大的冲击波
and it launched a blast of energy so powerful
在5万光年之外
that 50,000 light-years away
影响了我们的星球
it physically affected our planet.
幸运的是，这发生在银河系的另一边
Happily, this occurred halfway across the galaxy.
如果这件事发生得很近的话
If this thing had been a lot closer,
对我们的影响将是巨大的
the effect on us would have been huge.
最惊人发现
磁力
离地球几光年远的磁星
A magnetar a couple of light-years from earth
会毁灭我们的星球
would devastate our planet.
如果它发生一次辐射爆发
There could be a burst of radiation that could literally
会将我们的大气层剥离
strip away our atmosphere.
没有大气层，生命就没有呼吸的空气
Without an atmosphere, there's no air to breath.
动物的生命将会死亡
Animal life would die.
没有气压，海水也会沸腾
Without air pressure, the seas would boil away.
地球将作为一个没有生命的岩石球
Earth would be left as a lifeless ball of rock
在太空中旋转
spinning through space.
在宇宙中的每一个角落
Everywhere we look in the universe,
我们都能看到同样的东西遵循着同样的规则
we see the same stuff following the same rules.
宇宙其实只是
The universe is only made up
由少数几种基本成分组成
of a handful of basic ingredients ...
氢，氦，锂，碳等等
hydrogen, helium, lithium, carbon and so on.
所有这些化学物质
All of these chemicals, in different proportions,
以不同的比例构成了我们
are what make us up.
这些相同的化学物质
And these same chemicals, in different proportions,
以不同的比例构成了一切
make up everything.
构成星系和恒星的化学物质
The same chemicals that form galaxies and stars
在地球上也有惊人的作用，甚至可能是独一无二的
do something amazing on earth, perhaps even unique.
它们变成了有生命的东西——
They become living things,
能够生长、繁殖和思考的有机体
organisms that can grow, reproduce and think.
杜尔达:我们是宇宙中有意识的一部分
Durda: We are bits of the universe made conscious.
我认为这是……这是……这是生物学上的奇迹
I think that's a ... it's ... it's a biological miracle.
你看着天空，你知道你和它
You look out into the sky, and you know you're connected
有着某种联♥系♥
to that somehow.
这很神奇
It's pretty fantastic.
那么地球上生命的故事何时开始呢?
So when does the story of life on earth begin?
事实上，它早在地球存在之前就开始了
Actually, it begins long before earth existed.
大爆♥炸♥之后，宇宙只不过是
After the big bang, the universe is little more
一大♥片♥氢气云团
than a vast cloud of hydrogen gas.
然后，气体云的小块坍缩形成恒星
Then, pockets of the gas cloud collapse to form stars.
而且只有恒星
And only stars can turn hydrogen
才能将氢转化成更复杂的分子
into the more complex molecules that will become planets
从而形成行星和人类
and people.
在这些早期恒星的内核深处
Deep inside the cores of these early stars,
炽热的温度和巨大的压力
heat and pressure crush hydrogen atoms together
将氢原子猛烈地挤压在一起
so powerfully they fuse,
形成了氦原子并释放出巨大的能量
creating helium atoms and releasing a burst of energy.
随着时间的推移，氦原子也会融合在一起
Over time, helium atoms fuse together too, creating carbon,
然后产生碳氮、氧和更重的原子
nitrogen, oxygen and even heavier atoms.
几亿年以来
Over hundreds of millions of years,
古老的恒星形成了
ancient stars build up all the elements