史蒂芬·霍金之大设计（2012）

等于得对抗迎面而来的以太风 那光速应当会减缓
and so was fighting oncoming ether wind,the speed of light should slow down.
而这两种速度的差异应该可测量出来
And the difference between those two speeds should be measurable.
但他们测不出任何差异
But they couldn't detect any difference.
无论光波朝哪个方向
Whichever way the light waves were pointing...
他们都测不出任何速度增减
They couldn't find any slowing down or speeding.
这项结果令他们非常不安
This result was deeply disturbing.
光以太不可能存在
The luminiferous ether could not exist.
更有甚者 这表示无论往任何方向 光速始终维持恒定
What's more,it meant the speed of light must be constant in all directions.
现代实验已一再证实这项发现
Modern experiments have repeatedly confirmed this discovery.
无论光线往任何方向行进 光速永远维持不变
The speed of light remains fixed regardless of the direction in which it is traveling.
迈克尔孙和莫雷极尴尬地
Michelson and Morley were deeply embarrassed...
承认错误 以太根本就不存在
about having to report they being wrong. The ether simply wasn't there.
但这项实验非但不算一无可取
But the experiment wasn't a total disaster.
反而成为科学史上极重要的重大错误
It's one of the most important mistakes in the history of science.
光的行进完全不需介质 这个概念真是怪异
Light is a wave that travels through nothing. What a strange idea.
而光速恒定不变的这项发现 也非常奇特
And the discovery that the speed can not be varied,is also very odd.
幸好物理学家都喜欢怪异的事物
Likely,we physicists like strange things...
因为这种事常有助于获得突破
because it often leads to breakthroughs.
这项发现有助于取得最重大的突破
And this discovery led to the biggest breakthrough of all:
光速恒定不变的这项发现
The discovery that the speed of light is fixed...
会改变科学家对宇宙的所有认知
Would challenge everything we scientists believed about the universe.
这得请我的另一位英雄爱因斯坦
It would take another of my heroes,Albert Einstein...
才能发现光本质的深奥真♥相♥
to discover the deep truth about the nature of light.
为了解释他是如何办到的 我带大家回到我的童年
To explain how he did it,let me take you back to my childhood.
我以前的玩具火车 最适合用来解释爱因斯坦的深奥问题
My old toy train is a perfect way of illustrating Einstein's profound question...
光速恒定对宇宙的意义
of what the fixed speed of light meant for the universe.
爱因斯坦先从一个简单的问题开始
Einstein started with a simple question:
这列小火车的行进速度有多快
How fast is something like this little train moving?
当时是1950年代 玩具火车的品质并不怎么理想
Well,this is the 1950s and toy trains weren't all that good.
就假设行进速度大约每小时1600米吧
So let's say it's traveling at about one mile per hour.
但若改变观察点 就会有不同的答案
But change way you look at it from. You get a different answer.
地球以大约1600公里的时速绕着地轴旋转
The earth spins on its axes at around 1,000 miles per hour.
所以若从这里看 这列火车的速度就快得很多
So,seen from up here,my train is actually traveling much faster.
当然整体而言 地球绕着太阳旋转 且时速为108000公里
Of course,the earth as a whole is orbiting the sun at 67,000 miles per hour.
就连太阳也并非静止 而是绕着银河系的中心旋转
And even the sun isn't stationary. It is orbiting the center of the milky way.
而银河系也在太空中旋转
And the Milky Way is moving through space,too.
那么火车的行进速度究竟有多快？
So how fast is the train really moving?
答案完全取决于从哪里观察
Well,it all depends on way you see it from.
可能是每小时16公里
It could be 1 mile per hour,
每小时16000米 每小时10800公里
1,000 miles per hour,60,000 miles per hour...
甚至快好几倍
Or many times faster.
这是怎么回事？
So what's the problem?
大家都知道 速度多少是相对于观察点的
Anyone can understand that speed is relative to your perspective.
不同于玩具火车的车速
But when you remember that unlike the speed of the toy train...
无论从任何观察点 光速始终保持恒定
the speed of light is fixed no matter what your perspective...
因此一般的观点就开始瓦解
then that common sense view things starts to break down.
为了解释原因 爱因斯坦也想象出一列火车
To explain why Einstein imagined a train,too.
只不过是真实大小的
Only his was full-sized.
他设计了一项思考实验 探寻像点燃打火机这么简单的事
He devised a thought experiment,asking how something as simple as the lighting of a cigarette light tip...
为何不同的人会看到不同的结果
would look to people with different points of view.
他想象有人在车厢中♥央♥玩打火机
He imagined a man playing with his lighter in the center of a railway car...
车厢两头各有一个人在看
being watched by two people at either end.
两人与打火机的距离相等
Both at exactly the same distance from the lighter.
爱因斯坦表示值得探究的问题 不在这两人看见了什么
Einstein said the interesting question is not what do these people see...
而是何时看见
But when do they see it.
因为他们都在同一节车厢里以相同的速度前进
Because they're in the same car or moving together at the same speed...
两名观察的人都在同一时间看见火光
the two observers see the light at exactly the same time.
但车厢外的人呢？她会看见什么状况？
But what about someone outside? What do she see?
从她的角度来看 由于火车往前行驶
From her perspective,with the train moving forward...
前面的人需要多一点时间才能看到光束
the beam of light needs to travel a little bit further before it reaches the man at the front.
而另一方面 往后移♥动♥的火光
On the other hand,the light moving towards the man at the back...
需要移♥动♥的距离较短 因为后面的人朝着火光移♥动♥
has a slightly shorter distance to go,since he is moving towards it.
因此她先看见火光传往后面的人 再传到前面的人
So,she sees the light reach the man at the back before it hits the chap at the front.
有意思的是 行进列车上发生的事
What that means is that an event on a moving train...
若同在列车上就觉得是同时发生
takes place simultaneously if you're on the train...
但若在月台上就会觉得有时间差
But at different times when you're standing on the platform.
稍待片刻
Stop a moment...
想想这件事有何含义
and think about the implication of that.
这表示我们无法确定 事情是否真的同时发生
It means that we can't say if the events really happen at the same time or not.
现实本身取决于人的所在位置
Reality itself depends on where you are.
把此实验提升到整个宇宙的层次 就会变得更光怪陆离
Scale this up to the universe as a whole,and it gets even weirder.
若现实取决于人的位置
If reality depends on where you are...
那宇宙的实际状况又该如何得知
Then how can you know what's really going on in the universe.
更重要的是 我们查出的几率有多大
What's more,what chance do we stand to finding the key...
有关宇宙运作关键 如果我们自己都无法判定了
to how the universe works if we can't even tell if...
两件事是否同时发生
two events are simultaneous or not.
别担心 因为幸好爱因斯坦提出了解答
Don't worry,because Einstein thankfully came out with the answer...
在他著名的狭义相对论当中
in his famous theory of special relativity.
爱因斯坦提出弹性现实的理论 因为时间本身就有弹性
Einstein proposed that reality is flexible because time itself is flexible.
这听来可能很怪异 但这种弹性却开启了
It might sound strange,but this flexibility is just the start...
在物理学上全新的概念
of a whole new concept in physics.
爱因斯坦继续主张 就像磁性、电力和光线一样
Einstein went down to suggest that just like magnetism,electricity and light...
时间和空间都在彼此纠结 在他所称作"时空"中
both time and space are inextricably linked in what he called "spacetime".
而这个时空也有弹性
This spacetime is flexible as well.
时空的弯曲变形取决于重物的质量
It can be bended and warped by the shear mass of heavy things
好比恒星、行星
like stars,and planets...
以及星系
and galaxies.
但真正神奇的是这类变形也可解释
But what's really amazing,is this distortions also explain...
牛顿多年前所发现的神秘作用力
that mysterious force discovered by Newton so many years ago.
重力就是时空扭曲的结果
Gravity is the warping of spacetime.
时空扭曲 听来可能玄得让人摸不着头绪
Now,curving space and time may sound tricky wrap your head around.
但一点都不玄
But it's not.
想象一艘船锁定直线航道 正准备渡过平坦的湖面
Imagine a boat locked on the straight course across the flat surface of a lake.
一座永远无限延伸的湖
A lake that stretches away... forever.
平坦的湖面就如同未扭曲的时空
The flat lake is like undistorted spacetime.
现在想象湖面下出现一个大洞
Now imagine a giant hole appears beneath the lake...
湖水开始排掉
and water begins to drain away.
湖面因此扭曲 就如时空因行星扭曲一样
The lake has become distorted,just as spacetime is by a planet.
此作用会将船向洞里拉
The effect would be to drag the boat towards the hole...
因此船开始绕着洞周围航行
so that it begins to curve around it.
即使船本身仍设定在直线航行
Even though the boat is still being driven in a straight line.
这种作用就相当于 巨大恒星或行星
And it's exactly that same effect a massive star or planet has...
对时空产生的作用
on spacetime.
时空会在星体四周产生扭曲
It causes spacetime to distort around it,
把物体拉向星体
pulling things towards it.
因此物体才会坠落地球
And that's why things fall to earth:
就是因为重力
gravity.
爱因斯坦深入研究宇宙结构后 看出其深奥的作用原理
Einstein had lurked deep into the fabrique of the universe and seen its inner workings.
在他解释光速恒定10年后
Ten years after he explained the fixed speed of light...
他又发现时空扭曲
He discovered that the distortion of space and time...
会产生重力 这一自然界的基本作用力
produces gravity,a fundamental force of nature.
他的研究让人类更接近
His work brought us much closer...
解开宇宙奥秘的关键
to discovering the secret key to the cosmos.
但接着发生的事却出乎爱因斯坦的意料
But not even Einstein was prepared for what happen next.
尽管爱因斯坦已开始解开
Although Einstein had begun to reveal the universe's
隐藏的宇宙机制
hidden clockwork,
却仍不完全了解其作用原理
He still couldn't quite yet see how it operated.
他推论光的本质是
His theories drawn the nature of light...
超快的电磁波 在无垠的宇宙间快速行进
as a super fast electromagnetic wave racing through the emptiness of space.
却无法揭露这些电磁波的本质
But they revealed nothing about what these waves really are.
这项挑战在1919年间 由一名德国理论家接下
That challenge was taken up in 1919 by a German theorist,
他名叫卡鲁扎 这名追求纯净与优雅的数学家
named Theodore Kaluza,a mathematician with a passion for purity and elegance.
是我英雄榜上的下一名伟大科学家
The next great scientist in my pantheon of heroes.
卡鲁扎非常认真地钻研各种形式的理论
Kaluza was a man who took all forms of theory very seriously indeed.
据说他自学 学会了游泳
It's said that he taught himself to swim...
只读了一本介绍游泳的书
solely by reading a book on this subject.
卡鲁扎对实际应用理论毫无畏惧
Kaluza was fearless in putting theory into practice.
所幸他对游泳的理论了解得很透彻
Luckily for Kaluza,the theory of swimming was well understood.
但在1919年间 他的一项理论却并非如此
But in 1919 that couldn't be said for a theory that explain the universe:
这是一项解释宇宙万物的理论
A theory of everything.