宇宙时空之旅（2014）

Cosmos: A SpaceTime Odyssey S01E10

Part 4 April 25, 2021, 12:41 p.m.

Damn!
他陷入了绝望决定尝试一下玻璃砖
In desperation, he decided to try the glass brick,
他年复一年地被戴维使唤所得的纪念品
the souvenir of his years of bondage to Davy.
奇迹发生了
It did the trick.
磁力使光线扭转
The force of the magnet twisted the light
使光线穿过了水晶
so that it could pass through the crystal.
那有什么大不了的
So, what's the big deal?
法拉第向我们展示了
Faraday had demonstrated the existence
物理事实就存在于我们身边
of the physical reality that surrounds us,
但前人未曾发觉
but which no one had ever been able to detect.
这真是一种戏剧性的突破
It was as dramatic a breakthrough
就像人们第一次从天文望远镜中观察宇宙
as seeing the cosmos for the very first time through a telescope.
法拉第向我们展示
By showing that an electromagnetic force
电磁力能操纵光
could manipulate light,
他发现了自然界更深层次的统一性
Faraday had discovered a deeper unity of nature.
他不仅为爱因斯坦打开了一扇门
He had opened a door for Einstein
而且影响了之后所有的物理学家
and all the physicists who came after him
能够一睹宇宙中最基本的隐秘力量
to glimpse the interplay of hidden, primal forces
之间的相互作用
in the universe.
即使在他达到智慧巅峰之时
Even as he approached the summit of his genius,
抑郁症和对记忆力的怀疑
he was plagued by depression
也深深困扰着他
and doubts about his ability
他怀疑自己能不能记住最简单的想法
to retain even the simplest thoughts.
我亲爱的朋友我发现自己很难回复
My dear friend, I find a difficulty in answering
甚至是正确理解科学信件
or even acknowledging properly a scientific letter,
因为我现在一秒钟都记不住东西
for I cannot now hold it at once in my mind.
我的记忆日渐衰退
The memory of the parts fail me.
又及这封短♥信♥的语气
P.S. You will be sorry to see
肯定会让你感到遗憾
the tone of this short note,
但我最亲爱的丈夫的健康不如往日
but my dearest husband is not quite so well as usual,
我希望他能有所好转
but I hope he will improve.
你最诚挚的撒·法拉第
Yours very truly, S. Faraday.
年轻时法拉第自贫困中崛起
As a young man, Faraday had risen from poverty,
在世界上最注重等级的社会中成长
in one of the most class-conscious societies the world has ever known,
一跃成为那时最声誉卓著的科学家
to become the most celebrated scientist of his time.
在他40岁时他发明了电动机
By age 40, he had invented the electric motor,
变压器发电机
the transformer, the generator,
这些机器改变了家庭
machines that would change everything about the home,
农场工厂中的一切
the farm, the factory.
现在在这位伟大的物理学家60岁时
Now, at 60, decades after the fertile periods
他早已过了成果累累的时期
of the greatest physicists,
失忆和忧郁折磨着他
plagued by memory loss and melancholy,
但他无畏地继续深入探索
he fearlessly probed deeper
那看不见的神秘力量
into the mysterious invisible forces.
世人都以为迈克尔·法拉第已成为历史了
The world thought that Michael Faraday was a has-been.
尽管被抑郁困扰
Despite his depression,
他的好奇心依然强烈一如从前
he remained as passionately curious as ever.
在发现了电磁和光的统一性后
Having discovered the unity of electricity, magnetism and light,
法拉第想知道
Faraday needed to know
自然界中这三种力量是如何共同作用的
how this trinity of natural forces work together.
这就是女士们走过的路
This is the way the ladies walk...
这不是什么新鲜事儿
This was nothing new.
孩子们已经玩磁铁和铁屑
Children had been playing with magnets
玩了几个世纪了
and iron filings for centuries.
每个人都认为这些有趣的图案
Everyone had always assumed that this lovely pattern
是铁在起作用
was just something that iron did.
法拉第知道电流能把导线变成磁铁
Faraday knew that electric current turns a wire into a magnet,
所以他希望能在通电导线周围的铁屑中
so he expected to find related patterns in iron filings
找到类似的图案
around a wire carrying electricity.
其他人只看到有趣的图案
But where others saw merely lovely shapes,
法拉第发现了更深奥的东西
Faraday saw something profound.
这些图案不是由铁屑形成的
The patterns were not simply a quirk of iron filings;
它们存在于磁铁以及电路
they existed in the space around a magnet
周围的空间
or an electric current,
即使没有铁屑
even in the absence of iron filings.
这些图案就是蛛丝马迹脚印
The patterns were the traces, the footprints
来自看不见的力
of invisible fields of force,
存在于任何带有磁性的物体周围
that reached out into the space around anything magnetic.
千百年来人们对指南针的指针感到惊讶
The compass needle that people wondered at for a thousand years
其实它并不是对遥远的磁北极有所反应
was not reacting to some far away magnetic North Pole.
而是它探测到了来自磁北极的
It was detecting a continuous force field
连续不断的磁力场
that stretched all the way there.
地球本身就是一块大磁铁
Earth itself is a giant magnet.
和其他磁铁一样
And like any other magnet,
它的磁力线向四周延伸
its lines of force extend far out
深入地球周围的宇宙空间
into the space surrounding it.
它们在我们身边无处不在
They're everywhere, all around us.
一直如此
They've always been.
但之前未曾有人注意到
But nobody had ever noticed them before.
准确来说是没有人类
Nobody human, that is.
鸟类是恐龙仅存的后裔
Birds are the last living descendants of the dinosaurs.
鸽子以及其他鸟类
Pigeons and other birds
对于寻找飞行路线极其在行
are remarkably good at finding their way around.
它们可以迁徙上千千米却不迷路
They can migrate thousands of miles without getting lost.
如何做到一部分原因是识别沿途地标
How? Partly by recognizing familiar landmarks--
河流山脉星辰
rivers, mountains, stars.
候鸟甚至将某种气味
Even certain smells can serve as signposts
作为路标
for migrating birds.
但是鸟类也有内置罗盘
But birds also have an inner compass.
它们能感受到地磁场
They can actually sense the Earth's magnetic field.
它们的大脑能像我们的大脑处理视觉数据一样
Their brains process magnetic data in much the same way
处理磁数据
ours process visual data.
利用感受到的磁场方向
By sensing the direction of the field,
鸟类就能分辨南北
birds can tell north from south.
这就是为何北美鸟类
That's one way North American birds know which way to go
能够找到冬季南迁的路
when they head south for the winter.
两极的磁场强于
The field is stronger near the poles
赤道的磁场
than it is at the equator,
这就是鸟类推断纬度的办法
a fact that birds use to figure out their latitude.
磁场也有一些微小的不规则之处
There are also small irregularities in the field,
存在一些地方
locations where the field
磁场稍强或稍弱
is a little weaker or stronger.
就好像独特的山脉或河流
Just like a distinctive mountain or river,
这些磁场反常也可以作为地标
these magnetic anomalies can serve as landmarks.
千百年来人们用信鸽
For thousands of years, humans have used carrier pigeons
向远方发送信息
to send messages to distant locations.
在二战中仍是非常重要的通讯方式
It was a crucial method of communication as recently as World War II.
当你想起时这么长时间以来
When you think about it, we've been using
我们都一直在用磁场沟通
magnetic fields to communicate for a long time.
我们只不过没有察觉
We just didn't know it.
那么究竟是为什么地球有磁场呢
So why does our planet have a magnetic field at all?
是什么引起磁场
What causes it?
答案深埋于地球内部
The answer lies deep inside the Earth.
当地球自转时液态铁环绕着
Liquid iron, circulating around the solid part of the core
固体的地核旋转
as Earth rotates,
就像通电导线一样
acts like a wire carrying an electric current.
正如法拉第展示给我们的
And as Faraday showed us,
电流能产生磁场
electric currents produce magnetic fields.
这对人类而言是件好事
And that's a good thing.
我们的磁场保护我们免遭宇宙射线的攻击
Our magnetic field protects us from the onslaught of cosmic rays,
宇宙射线对生物圈危害极大
which would be very damaging to our biosphere.
宇宙射线能穿透DNA
Cosmic rays can rip through DNA.
如果没有磁场生物体的变异几率
Without our magnetic field, the rate of mutation in living organisms
将大大提高
would be much higher.
幸运的是大多数的宇宙射线
Fortunately, most of this cosmic shrapnel
都被范艾伦辐射带吸收了
gets trapped in the Van Allen belts,
磁场把带电粒子聚集在一起
donut-shaped zones of charged particles
形成了这个面包圈状的空间
corralled by our magnetic shield.
知道地球本身就是一块大磁铁之后
Knowing that the Earth itself is like a giant bar magnet
我们就可以解释天空中最美的景色之一
explains one of the most beautiful sights in the sky,
极光