One of the funny things about owning a brain

擁有大腦的有趣之處在於

is that you have no control over the things that it gathers and holds onto,

你無法控制大腦如何收集與保留

the facts and the stories. And as you get older, it only gets worse.

事實和故事。而當你越來越老, 事情只會變得更糟

Things stick around for years sometimes

有些事情會留在你的腦袋裡很多年

before you understand why you're interested in them,

你根本不知道為什麼會一直記著這些事

before you understand their import to you.

也不清楚到底是怎麼把它記起來的。

Here's three of mine.

以下我有三個例子

When Richard Feynman was a young boy in Queens,

當理查 · 費曼還是一個小男孩, 住在皇后區

he went for a walk with his dad and his wagon

有一次他和他的父親去散步, 拉著他的玩具拖車

and a ball. And he noticed that when he pulled the wagon,

上面放了一個球。他注意到，當他拉車的時候

the ball went to the back of the wagon.

球會往拖車後面跑

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

他問他的爸爸, "為什麼球會跑到拖車的後面呢？"

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

他的父親說, "這是慣性。"

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

他問說, "慣性是什麼？" 他的父親說, "啊。

Inertia is the name that scientists give

慣性是科學家們給的名稱

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

用來描述球跑去拖車後面的這種現象。

But in truth, nobody really knows."

但事實是, 沒有人真正知道這現象到底是怎麼一回事。"

Feynman went on to earn degrees

費曼後來取得了學位

at MIT, Princeton, he solved the Challenger disaster,

在麻省理工學院、 普林斯頓大學, 他還解決了挑戰者號太空梭爆炸的謎團,

he ended up winning the Nobel Prize in Physics

他還得到了諾貝爾物理學獎,

for his Feynman diagrams describing the movement of subatomic particles.

因為他在描述亞原子粒子的運動方面的成就

And he credits that conversation with his father

他把一切歸功於那次與他父親的對話

as giving him a sense

給了他一個啟發:

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

從最簡單的問題開始, 可以帶領你探索到人類知識的前鋒,

and that that's where he wanted to play.

這就是他想做的

And play he did.

而他也如此做到了

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

第二個例子, 艾拉托斯特尼是亞歷山大 一個偉大圖書館的第三任館長

and he made many contributions to science.

他在科學方面有很多貢獻。

But the one he is most remembered for

其中最讓人津津樂道的

began in a letter that he received as the librarian,

是在他當圖書館館長時, 收到了一封信

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

寄自亞歷山大城南邊的斯威尼特鎮。

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

這封信提到的一件事, 一直在艾拉托斯特尼的心中揮之不去

and the fact was that the writer said at noon

寫信的人說, 當他在夏至的中午

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

望進一口深井的時候

he could see his reflection at the bottom, and he could also see that his head

他可以看到井底的水面, 有陽光反射, 而且他的頭

was blocking the sun.

正好可以擋住太陽。

Now, I should tell you -- the idea that Christopher Columbus discovered that the world is spherical

而我應該告訴你, 關於克里斯多夫 · 哥倫布 發現地球是球形的這回事

is total bull. It's not true at all.

根本就是胡扯。完全不正確。

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

事實上, 受過教育的人都知道地球是圓的

since Aristotle's time, and Aristotle had proved it

因為在亞里斯多德的年代, 他就已證明了這事

with a simple observation.

只靠簡單的觀察。

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

他注意到, 每次在月亮上看到地球的影子(月食)

it was circular,

影子是圓的

and the only shape that constantly creates a circular shadow

而唯一能每次都造成圓影的形狀

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

就是一個球體, 所以證明地球是圓的。

But nobody knew how big it was

但沒有人知道地球有多大

until Eratosthenes got this letter with this fact.

直到艾拉托斯特尼有了這封信跟井的這回事。

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

他想到太陽是斯威尼特鎮的正上方

because looking down a well, it was a straight line

因為向井下頭看, 這是一條直線

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

從太陽經過寫信者的頭, 一路到井底。

Eratosthenes knew another fact.

艾拉托斯特尼知道另一個事實。

He knew that a stick stuck in the ground in Alexandria

他知道在亞歷山大城當地立了一根棍子

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

在同一時間、 同一天中午,

the sun's zenith, on the solstice,

太陽正在天頂的時候

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

陽光照出的棍子的陰影與鉛直線偏了 7.2 度。

Now, if you know the circumference of a circle,

現在, 如果你知道一個圓的圓心角

and you have two points on it,

還有圓上的兩個點

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

你只要知道這兩點之間的距離

and you can extrapolate the circumference.

就可以推算出圓周長。

Three hundred and sixty degrees divided by 7.2 equals 50.

360 度除以 7.2 度等於 50。

I know it's a little bit of a round number, and it makes me suspicious of this story too,

我知道正好整除有些太巧了, 讓人有點懷疑這個故事的可信度

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

但這是一個好故事, 所以我們會繼續談下去。

He needed to know the distance between Swenet and Alexandria,

他需要知道斯威尼特鎮 和亞歷山大城之間的距離

which is good because Eratosthenes was good at geography.

這是容易的, 因為艾拉托斯特尼很擅長地理學。

In fact, he invented the word geography.

事實上, 地理學這個名詞就是他發明的。

The road between Swenet and Alexandria

斯威尼特鎮 和亞歷山大之間的道路

was a road of commerce,

是一條經商者常走的路,

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

經商者需要知道路程要多久。

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

所以實際的距離很重要, 所以他也非常精確地知道

that the distance between the two cities was 500 miles.

這兩個城市之間的距離是 500 英哩。

Multiply that times 50, you get 25,000,

乘上 50 倍, 就是 25,000 英哩,

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

這跟地球實際的大小只有 1% 的誤差。

He did this 2,200 years ago.

在二千二百年前, 他就能做到這樣的事。

Now, we live in an age where

現在, 我們生活在一個時代,

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

價值數十億元的設備正在尋找希格斯玻色子。

We're discovering particles that may travel faster than the speed of light,

我們發現可能比光速更快的粒子

and all of these discoveries are made possible

而所有的這些發現都是靠著

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

在過去幾十年中所發展出來的科技。

But for most of human history,

但在人類歷史的大多數時間,

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

我們只能靠我們的眼睛和耳朵, 還有思考能力, 來發現新事物。

Armand Fizeau was an experimental physicist in Paris.

阿曼德斐索是在巴黎的實驗物理學家。

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

他的專長是精煉和確認其他人的研究結果,

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

這聽起來可能有點的遜,

but in fact this is the soul of science,

但事實上, 這就是科學的靈魂

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

因為若不能獨立的被重複驗證, 就不能被稱為科學事實。

And he was familiar with Galileo's experiments

他很熟悉伽利略的一個實驗

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

是關於光是不是有速度的。

So, Galileo had worked out this really wonderful experiment

伽利略曾做了這個特別的實驗

where he and his assistant had a lamp,

他和他的助手各拿了一盞燈,

each one of them was holding a lamp. And Galileo would open his lamp, and his assistant would open his lamp.

當伽利略打開他的燈, 他的助手看到光後, 也同樣地打開燈。

And they got the timing down really good.

他們把時間抓得很準。

They just knew their timing. And then they stood at two hilltops,

他們只管自己的開燈時機。 然後他們站在兩個山頭

two miles distant, and they did the same thing, on the assumption

相距兩英里, 兩人做一樣的事情,

from Galileo that if light had a discernable speed,

伽利略的假設是, 如果光有一個特定的速度,

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

他應該會注意到在從他的助手燈回來的光的延遲。

But light was too fast for Galileo.

但光的速度對伽利略來說太快了。

He was off by several orders of magnitude when he assumed

他對光的速度的臆測差了好幾個數量級 (10的n次方)

that light was roughly 10 times as fast as the speed of sound.

他猜測光大概只比聲音的速度快 10 倍。

Fizeau was aware of this experiment. He lived in Paris,

斐索聽說了這個實驗。他住在巴黎,

and he set up two experimental stations,

他設立了兩個實驗站

roughly five and a half miles distant,

相距大約五英里半,

in Paris. And he solved this problem of Galileo's,

在巴黎。他解決了伽利略的實驗中的問題,

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

他只用了一塊相對來說很小的設備。

He did it with one of these.

他用的就像這個。

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

我先把遙控器收起來,

because I want to engage your brains in this.

因為我想讓你的大腦也來思考一下。

So this is a toothed wheel. It's got a bunch of notches

這就是齒輪的樣子。它有一大堆的凹槽

and it's got a bunch of teeth.

還有一堆的凸齒。

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

這是斐索用來發送離散脈衝光的作法。

He put a beam behind one of these notches.

他讓一束光穿過這些凹口之一。

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

射到另一個實驗站的鏡子反射

five miles away, that beam is bouncing off the mirror

來回各五英里, 這束光回來後

and coming back to me through this notch.

會通過這個凹口被看到。

But something interesting happens as he spins the wheel faster.

但當他把齒輪轉得更快時, 有趣的事情發生了。

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

他觀察到如同反射的光被關上的門擋住了

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

眼睛看不到反射回來的光了。

Why is that?

這是為什麼？

It's because the pulse of light, it's not coming

這是因為反射的光並沒有

back through the same notch. It's actually hitting a tooth.

通過發射時相同的凹口。 實際上是擊中一顆凸齒。

And he spins the wheel fast enough

他把齒輪轉得夠快

and he fully occludes the light. And then,

對光的現象充分的觀察

based on the distance between the two stations

再依據兩個地點之間的距離

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

還有他的齒輪的轉速與齒數

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

他計算出與實際光速誤差不到 2% 的數值。

And he does this in 1849.

他在 1849 年作出了這樣的實驗。

This is what really gets me going about science.

這也是為什麼讓我對科學一直有興趣的緣故。

Whenever I'm having trouble understanding a concept, I go back and I research the people that discovered that concept.

每當我在理解一個概念時遇到了問題, 我會回去研究發現了這個概念的研究者。

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

我觀察他們如何逐漸搞懂整件事情。

And what happens when you look at what the discoverers were thinking about

當你看到了研究者如何思考,

when they made their discoveries, is you understand

看到他們如何發現事物, 你就會知道

that they are not so different from us.

其時他們跟我們沒有什麼不同。

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

我們都是血肉之軀。我們都能使用相同的工具。

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

我很喜歡把科學的不同分支稱做研究領域的說法。

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

大多數人認為科學是封閉的黑箱,

when in fact it is an open field.

當事實上它是一個開放的領域。

And we are all explorers.

而且我們大家都是探險家。

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

貢獻出這些發現的人只是想得比我們努力些

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

對於他們所研究的事情, 有著更多的好奇心

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

他們的好奇心改變了人們對這個世界的觀點,

and thus it changed the world.

也因此而改變了世界。

They changed the world, and so can you.

他們能改變這個世界, 當然你也可以。

Thank you.

謝謝。

(Applause)

（掌聲）