宇宙（2007）

The Universe S05E03

Part 2 April 22, 2021, 1:49 p.m.

Electricity and magnetism are really one and the same thing.
电和磁可以说就是一回事
For something so fundamental,
在这些基本力量中
Magnetism often gets overlooked.
磁力经常会被忽视
Besides holding notes on your refrigerator,
除了在冰箱上粘一张便条
magnets rarely show up in an average person's daily life.
磁铁很少出现在人们的日常生活中
Magnetism is not something that we normally deal with.
我们通常不怎么用到磁力
You can't feel a magnetic field.
你感觉不到磁场
You can run a magnet over yourself and you don't feel a thing.
把磁铁从自己身上掠过时你感觉不到任何东西
So it isn't part of our daily experience.
所以日常生活中我们感觉不到磁力
The key component of magnetism
磁力的关键在于
is that it attracts and repels.
吸引和排斥
I'm holding here two magnets to illustrate
我用这两块磁铁来说明
how magnetic Fields work
磁场怎么发挥作用
and, frankly, how strong they are.
以及磁力有多大
Right now, they're attracting one another
现在它们相互吸引
and I have to really pull to pull them apart.
我得用力拉才能把它们分开
But they also can repel each other,
但是它们也能相互排斥
And I can illustrate it by putting it on this post.
通过把它放在这个杆上就可以说明
If I put first one down
我把第一块放下去
and drop the second one,
然后放下第二块
I really can't push it down.
第二块确实放不下去
It just bounces.
它弹起了
In fact, the only thing that keeps people from walking through walls
事实上使人们不能穿墙而过
or falling through the floor is magnetism.
也不能穿越楼板掉下楼的唯一力量就是磁力
Molecules and atoms are extremely small
分子原子极其小
and the space between atoms is extremely large.
原子之间的空隙又极其大
At an atomic level, almost everything is made of empty space.
以原子来看每一个事物都有着巨大的空间
The distance between the electrons that are orbiting around
原子核中电子围绕着质子运转
the protons in the nucleus is fairly immense.
两者之间的距离是相当大的
It's like this fan.
就像这个风扇
If you let the electrons be the blade
假设扇叶就是电子
and the center be the nucleus,
中心就是原子核
If there's no motion taking place there,
如果风扇没有动起来
you would pass right through things.
其他东西就可以从中穿过
It's not solid.
它不是连成一片的
So why is it solid?
为什么它连成了一片
It's because the electromagnetic attraction between
因为带负电荷的电子
the negatively charged electron
和带正电荷的质子之间
and the positively charged proton,
在电磁作用下相互吸引
It captures it and it spins around.
电磁吸引使它绕转起来
So if it's spinning really fast
如果绕转速度非常快
like the fan blades of this fan
就像这个风扇的扇叶
representing the electrons around the atom,
表示围绕着原子的电子
it bounces right off.
其他东西会被弹开
That's why you don't fall through the floor
那就是你不会穿越楼板掉下楼
and why you can't walk through walls.
也不能穿墙而过的原因
It's not the atoms themselves,
并不是原子本身
but the magnetic field that makes matter solid.
而是磁场使得物质连成一片
That keeps a person from walking through walls.
因此人们不能穿墙而过
Magnetic force attracts and repels
磁力沿着磁力线
along field lines.
产生吸引和排斥作用
You can take the bar magnet
拿一块磁棒
and lay a piece of paper over it
然后放一张纸在上面
and cover that piece of paper with iron filings.
在纸上撒上铁屑
And the iron filings will actually line themselves up
这些铁屑就会
along the field lines coming out of the magnet.
沿该磁场的磁力线排列起来
And that's a good way to see
这是个好办法
what the magnetic field actually looks like.
能观察到磁场的样子
One way to think of field lines
另一个办法是把这些磁力线想像成
is like lanes on a freeway.
高速公路的车道
The south-bound traffic never interacts with the north-bound traffic.
南行方向的车流与北行方向的车流互不相干
Electromagnetic field lines are like lanes on a freeway:
电磁场线就像高速公路的车道
Cars go down the lanes, down the freeway.
车都沿着高速路的车道开
And that's why if you look on the surface of the Sun,
那就是为什么当你看太阳表面时
you see these beautiful arcs
会看见许多美丽的弧
That represent the field lines where the plasma can flow.
那就是等离子沿着流动的磁力线
But on the surface of the Sun,
但是在太阳的表面
these field lines are intensely powerful and deadly.
这些磁力线含有巨大能量且致命
In this freeway analogy,
用高速公路来作比方
imagine if a middle lane was opened up on the freeway
试想如果在公路上的南北向高速行驶的车流中
between the speeding north and south traffic.
开了一条中间的车道
And there is no instruction
而且也没有一个路牌
as to who is supposed to go on that lane.
来说明哪个方向的车应该走这条道
You'll get a big mash up right there
那么这条车道
where the car is.
就会一团混乱
Everyone is trying to go on that lane
每个人都想驶上这条车道
and chaos ensues and there's a big release of energy.
随之而来就会发生混乱以及会释放出大量能量
Now imagine
现在再试想一下
if this freeway was on the Sun
这条高速路就在太阳表面
and the cars were 20,000 miles long.
这段车流足有两万英里长
The enormous crash fires material off the Sun
这起巨大的事故导致太阳向外发射物质
and straight toward our planet.
径直冲向地球
That is a Coronal Mass Ejection.
这就是日冕物质抛射
A CME is gigantic,
CME非常巨大
over 10 billion tons of solar plasma.
含有超过十亿吨♥的太阳等离子体
It's the equivalent of 100,000 aircraft carriers
相当于10万艘航♥空♥母舰
traveling at several million miles per hour toward Earth.
以每小时数百万英里的速度冲向地球
This is the threat to our planet.
这威胁到我们整个星球
A direct hit from a CME is a rare occurrence,
日冕物质抛射通常不会直接攻击地球
but it would be catastrophic for our civilization.
但是一旦攻击就会给我们的文明带来巨大灾难
We're literally one big storm away
只消一场大磁暴
from an engineering disaster.
就能给我们的工程带来灭顶之灾
The sheer size of that disaster has only become clear
来自太阳能科学的最新报告让我们更加明了
with new reports from the cutting edge of solar science.
灾难的规模之宏大
Disturbing new information from satellites
来自卫星的令人不安的新信息
might help us predict
也许能帮助我们预测
the next deadly blast of a magnetic superstorm.
下一个致命性的超级大磁暴
Magnetic solar storms have only recently been
直到最近人们才发现
shown to be a deadly threat to the Earth.
太阳磁暴是地球的致命威胁
The Sun is constantly ejecting material,
太阳一直在向外抛射物质
from radiation to x-rays
从放射物到X射线
to solar flares to coronal mass ejections.
到太阳耀斑到日冕物质抛射种种皆有
The reason these ejections don't routinely hit us
这些物质通常没有击中我们
is that Earth is protected.
是因为地球有保护层
The Earth has this huge magnetic field surrounding it.
地球被巨大的磁场所包围
It's all around the thing.
它包围着整个地球
and what happens is, if there's a solar flare,
无论是太阳耀斑
a coronal mass ejection,
还是日冕物质抛射
our magnetic field is our savior, it's our armor.
我们的磁场就是我们的救星我们的盔甲
Imagine the Earth
比方说这地球仪
as this globe,
就是我们的地球
and the Sun is a shotgun.
而太阳此时是这支猎枪
The Sun fires off powerful blasts
太阳每隔几天
toward the Earth every few days.
便向地球攻击一阵
But the planet
但地球
has a protective shield,
有一层防护罩
like a sheet of Plexiglas
就像一块树脂玻璃板
that protects a globe
可以保护这只地球仪
from shotgun blasts.
免遭子弹射中
It's called the magnetosphere,
它叫磁层
a gigantic magnetic field
是由地球剧烈流动的内核
generated by the planet's churning core.
发出的强烈磁场
It extends out 43,000 miles.
外延足有四万三千英里
Just as a ring magnet
就像两条环形磁铁
repels another ring,
互相排斥一样
Earth's magnetosphere repels
地球的磁层也会排斥
the magnetized plasma from the Sun.
来自太阳的磁化等离子体
A billion tons of superheated,
十亿吨♥过热的
electrically-charged plasma
并带电的等离子
hits our planet,
向地球袭来