How simple ideas lead to scientific discoveries

简单构想如何引领科学发现

Translator: Jenny Zurawell

翻译人员: Li Huayang 校对人员: Keke Gu

（音乐）

关于大脑有一个非常有趣的现象

One of the funny things about owning a brain

is that you have no control over the things

那就是我们无法控制大脑收集和掌握的信息，

that it gathers and holds onto, the facts and the stories.

无论是事实还是故事。而且年纪越大，情况就越糟糕。

And as you get older, it only gets worse.

有时候这些事物已经跟随你许多年了，

Things stick around for years sometimes

before you understand why you're interested in them,

你却还没弄清为何会对这些事物感兴趣，

还没了解他们对你的重要性。

before you understand their import to you.

我这有三个例子。

Here's three of mine.

When Richard Feynman was a young boy in Queens,

理查德 费曼小的时候住在纽约皇后区，

he went for a walk with his dad and his wagon and a ball.

有一次他和他爸爸推着车出去散步，

车上有一个球。他注意到当他拉动车子的时候，

He noticed that when he pulled the wagon, the ball went to the back of the wagon.

球就会滚到车的后面。

他问爸爸：“为什么球会滚到车的后面？”

He asked his dad, "Why does the ball go to the back of the wagon?"

爸爸回答说：“这叫惯性。”

And his dad said, "That's inertia."

He said, "What's inertia?" And his dad said, "Ah.

他接着问：“什么叫惯性？” 爸爸说：“啊。

惯性嘛，就是科学家们

Inertia is the name that scientists give

to the phenomenon of the ball going to the back of the wagon."

给’球滚到车后面‘这种现象取的名字。

(Laughter)

但事实上，没人明白这是怎么回事。“

"But in truth, nobody really knows."

费曼后来在麻省理工学院和普林斯顿获得了学位，

Feynman went on to earn degrees

他解决了挑战者号航天飞机失事事件的谜团，

at MIT, Princeton, he solved the Challenger disaster,

他最后获得了诺贝尔物理学奖

he ended up winning the Nobel Prize in Physics

因他提出的描述粒子运动的费曼图。

for his Feynman diagrams, describing the movement of subatomic particles.

他把这归功于和父亲的那次对话，

And he credits that conversation with his father as giving him a sense

让他认识到

that the simplest questions could carry you out to the edge of human knowledge,

最简单的问题可以将你带入人类知识的前沿，

而且那就是他想有所作为的地方。

and that that's where he wanted to play.

他确实成功了。

And play he did.

Eratosthenes was the third librarian at the great Library of Alexandria,

埃拉托斯特尼是亚历山大图书馆的第三任馆长，

and he made many contributions to science.

他为科学做出了很多贡献。

但他最为人们所铭记的成就

But the one he is most remembered for

began in a letter that he received as the librarian,

是由他在当图书馆馆长时收到的一封信开始的，

from the town of Swenet, which was south of Alexandria.

这封信来自亚历山大南边的一个叫塞尼的小镇（现埃及的阿斯旺）。

信中的一个事实在埃拉托斯特尼的脑中挥之不去，

The letter included this fact that stuck in Eratosthenes' mind,

写信的人说在夏至的正午时分，

and the fact was that the writer said,

at noon on the solstice, when he looked down this deep well,

当他向一口深井望下去的时候，

he could see his reflection at the bottom,

他可以看到井底的倒影，并发现他的头

and he could also see that his head was blocking the sun.

正遮挡着太阳。

I should tell you -- the idea that Christopher Columbus

现在我告诉大家，哥伦布发现地球是圆的这个说法

discovered that the world is spherical is total bull.

纯属是胡说八道，根本不是真的。

It's not true at all.

事实上，所有受过教育的人都知道地球是圆的

In fact, everyone who was educated understood that the world was spherical

这是自从亚里士多德时代起，而且亚里士多德本人

since Aristotle's time.

Aristotle had proved it with a simple observation.

还通过一个非常简单的观测证明过这个说法。

他注意到地球在月亮上的影子

He noticed that every time you saw the Earth's shadow on the Moon,

是圆的，

it was circular,

而且唯一能够持续的产生圆形影子的形状

and the only shape that constantly creates a circular shadow

就是球体，证明完毕。地球是圆的。

is a sphere, Q.E.D. the Earth is round.

但是没有人知道地球有多大，

But nobody knew how big it was

until Eratosthenes got this letter with this fact.

直到埃拉托斯特尼看到这封信里描述的事实。

他知道当时太阳在直射塞尼

So he understood that the sun was directly above the city of Swenet,

because looking down a well, it was a straight line

因为向井底看的时候，一条垂直光线

all the way down the well, right past the guy's head up to the sun.

经过那个人正当着太阳的头部，直射到井底。

埃拉托斯特尼还知道另一个事实。

Eratosthenes knew another fact.

He knew that a stick stuck in the ground in Alexandria

他知道在同一天的同一时间，

at the same time and the same day, at noon,

也就是夏至的正午，

the sun's zenith, on the solstice,

在亚历山大插一根棍子，

the sun cast a shadow that showed that it was 7.2 degrees off-axis.

从太阳投射的影子得知光线偏离轴线7.2度。

如果你知道一个圆周边，

If you know the circumference of a circle, and you have two points on it,

在圆上取两个点，

all you need to know is the distance between those two points,

只需要知道这两点之间的距离，

and you can extrapolate the circumference.

然后就可以推算周长了。

360 degrees divided by 7.2 equals 50.

360度除以7.2等于50。

我知道这是个整数，这也让我对这个故事产生了怀疑

I know it's a little bit of a round number,

and it makes me suspicious of this story too,

但它仍是个不错的故事，所以我们继续讲下去。

but it's a good story, so we'll continue with it.

他需要知道塞尼和亚历山大之间的距离，

He needed to know the distance between Swenet and Alexandria,

这个问题很好解决，因为埃拉托斯特尼很擅长地理。

which is good because Eratosthenes was good at geography.

事实上，是他创造了地理这个词。

In fact, he invented the word geography.

(Laughter)

塞尼和亚历山大之间的路

The road between Swenet and Alexandria was a road of commerce,

是一条商业之路，

and commerce needed to know how long it took to get there.

商人们需要知道多久能到达目的地，

It needed to know the exact distance, so he knew very precisely

就有必要知道两地的确切距离，所以埃拉托斯特尼

that the distance between the two cities was 500 miles.

非常精确的知道两地之间距离500英里。

Multiply that times 50, you get 25,000,

再乘以50，得到25000，

which is within one percent of the actual diameter of the Earth.

这与地球实际周长的误差不到百分之一，

但他在2200年前就做到了。

He did this 2,200 years ago.

现在我们生活的时代

Now, we live in an age where

multi-billion-dollar pieces of machinery are looking for the Higgs boson.

有价值几十亿美金的机器用来寻找希格斯玻色子。

We're discovering particles

我们正在探究比光速传播更快的粒子，

that may travel faster than the speed of light,

这一切科学探索成为可能

and all of these discoveries are made possible

是依靠过去几十年来的科技进步。

by technology that's been developed in the last few decades.

But for most of human history,

但是在大部分人类历史上，

我们不得不用自己的眼睛、耳朵和大脑来探索问题。

we had to discover these things using our eyes and our ears and our minds.

阿曼德·斐索是巴黎一名实验物理学家，

Armand Fizeau was an experimental physicist in Paris.

His specialty was actually refining and confirming other people's results,

他的专业领域是确认和完善他人的成果，

这听上去似乎有点无足轻重。

and this might sound like a bit of an also-ran,

but in fact, this is the soul of science,

但事实上，这正是科学的精髓，

because there is no such thing as a fact that cannot be independently corroborated.

因为没有一件事实不可以被独立证明。

他很熟悉伽利略试图的实验

And he was familiar with Galileo's experiments

来判断光是否拥有速度。

in trying to determine whether or not light had a speed.

伽利略精彩绝伦的实验室这样完成的

Galileo had worked out this really wonderful experiment

where he and his assistant had a lamp, each one of them was holding a lamp.

他和助手各有一盏灯，

他们每人提一盏灯，伽利略打开他的灯，助手也打开自己的灯。

Galileo would open his lamp, and his assistant would open his.

他们的时机把握得很好。

They got the timing down really good.

They just knew their timing.

他们很清楚自己的时机。他们分别站在两个山顶上，

And then they stood at two hilltops,

two miles distant, and they did the same thing,

距离两英里，然后做同样的事情

on the assumption from Galileo that if light had a discernible speed,

按照伽利略的假设，如果光线拥有可识别速度，

he'd notice a delay in the light coming back from his assistant's lamp.

他就会注意到从助手那里返回光线的延时。

But light was too fast for Galileo.

但对于伽利略来讲，光线实在是太快了，

当他假设光速大约是声速的10倍时，

He was off by several orders of magnitude when he assumed

that light was roughly ten times as fast as the speed of sound.

他少说了好几个数量级。

Fizeau was aware of this experiment.

斐索很清楚这个实验。他住在巴黎，

He lived in Paris, and he set up two experimental stations,

于是他在那建立了两个实验站点，

大约相距5.5英里。

roughly 5.5 miles distant, in Paris.

他解决了伽利略的问题，

And he solved this problem of Galileo's,

and he did it with a really relatively trivial piece of equipment.

而且他的实验器材相对来讲十分普通，

他就是用的这个。

He did it with one of these.

我要把这个遥控器先放在一边，

I'm going to put away the clicker for a second

because I want to engage your brains in this.

因为我要让你们的大脑也活跃起来。

So this is a toothed wheel.

这是一个齿轮，有一串凹槽，

It's got a bunch of notches and it's got a bunch of teeth.

还有一串轮齿。

This was Fizeau's solution to sending discrete pulses of light.

这就是斐索发送离散脉冲光的方法。

He put a beam behind one of these notches.

他将一束光线放在其中一个凹槽后面。

If I point a beam through this notch at a mirror,

如果我让这束光线通过这个凹槽射向一面五公里之外的镜子

这束光线由镜面反射回来

five miles away, that beam is bouncing off the mirror

and coming back to me through this notch.

通过这个凹槽回到我这里。

但当他快速转动齿轮时，有趣的现象发生了

But something interesting happens as he spins the wheel faster.

他注意到就好像是有一扇门在阻挡着

He notices that it seems like a door is starting to close

on the light beam that's coming back to his eye.

返回他视野的光线

Why is that?

为什么会这样？

这是因为光线返回的时候

It's because the pulse of light is not coming back

through the same notch.

通过的不是同一个凹槽。实际上，光线撞到了一个轮齿上。

It's actually hitting a tooth.

And he spins the wheel fast enough and he fully occludes the light.

当他把齿轮转得足够快的时候

光线被完全阻挡了

And then, based on the distance between the two stations

然后，根据两个实验站点的距离

and the speed of his wheel and the number of notches in the wheel,

和齿轮的转速以及齿轮上凹槽的数量

he calculates the speed of light to within two percent of its actual value.

他计算出了光的速度，和真实的光速只有百分之二的误差。

而他在1849年就做到了。

And he does this in 1849.

这就是我从事科学研究的原因。

This is what really gets me going about science.

Whenever I'm having trouble understanding a concept,

每当我理解不了某个概念时，我就回过头研究那些发现这个概念的人们。

I go back and I research the people that discovered that concept.

我要看看他们是如何理解这个概念的。

I look at the story of how they came to understand it.

What happens when you look

当你看到这些科学发现者是如何思考他们的探索研究的时候

at what the discoverers were thinking about

when they made their discoveries,

你就会明白

is you understand that they are not so different from us.

其实他们和我们没有什么不同

我们都是塞着肉、装着水的皮囊， 使用的都是同样的工具

We are all bags of meat and water. We all start with the same tools.

我喜欢这种把不同的科学分支称为学科领域的说法，

I love the idea that different branches of science are called fields of study.

大多数人认为科学就是一个封闭的黑匣子

Most people think of science as a closed, black box,

when in fact it is an open field.

实际上它却是一片广阔天地

And we are all explorers.

我们都是探险家。

那些在科学探索中取得成就的人仅仅是对他们看到的东西

The people that made these discoveries just thought a little bit harder

about what they were looking at, and they were a little bit more curious.

思考得更认真一点，并且他们的好奇心更多一点罢了，

And their curiosity changed the way people thought about the world,

他们的好奇心改变了人们看世界的方法，

and thus it changed the world.

进而改变了这个世界。

They changed the world, and so can you.

他们改变了世界，你们大家也可以。

谢谢。

Thank you.

(Applause)

（掌声）