TED-Ed
Adam Savage: How simple ideas lead to scientific discoveries
Filmed:
Readability: 3.6
2,830,544 views
Adam Savage walks through two spectacular examples of profound scientific discoveries that came from simple, creative methods anyone could have followed -- Eratosthenes' calculation of the Earth's circumference around 200 BC and Hippolyte Fizeau's measurement of the speed of light in 1849. Find more TED-Ed videos on our new YouTube channel: youtube.com/TEDEd.
Adam Savage - Maker, critical thinker
Adam Savage is an internationally renowned television producer, host and public speaker. Full bio
Adam Savage is an internationally renowned television producer, host and public speaker. Full bio
Double-click the English transcript below to play the video.
（音乐）
关于大脑有一个非常有趣的现象
00:14
One of the funny things
about owning a brain
about owning a brain
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那就是我们无法控制大脑收集和掌握的信息，
00:16
is that you have
no control over the things
no control over the things
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00:18
that it gathers and holds onto,
the facts and the stories.
the facts and the stories.
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无论是事实还是故事。而且年纪越大，情况就越糟糕。
00:21
And as you get older, it only gets worse.
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有时候这些事物已经跟随你许多年了，
00:23
Things stick around for years sometimes
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你却还没弄清为何会对这些事物感兴趣，
00:25
before you understand
why you're interested in them,
why you're interested in them,
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还没了解他们对你的重要性。
00:28
before you understand their import to you.
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我这有三个例子。
00:30
Here's three of mine.
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理查德 费曼小的时候住在纽约皇后区，
00:31
When Richard Feynman
was a young boy in Queens,
was a young boy in Queens,
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有一次他和他爸爸推着车出去散步，
00:34
he went for a walk with his dad
and his wagon and a ball.
and his wagon and a ball.
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车上有一个球。他注意到当他拉动车子的时候，
00:38
He noticed that when he pulled the wagon,
the ball went to the back of the wagon.
the ball went to the back of the wagon.
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球就会滚到车的后面。
他问爸爸：“为什么球会滚到车的后面？”
00:42
He asked his dad, "Why does
the ball go to the back of the wagon?"
the ball go to the back of the wagon?"
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爸爸回答说：“这叫惯性。”
00:45
And his dad said, "That's inertia."
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00:47
He said, "What's inertia?"
And his dad said, "Ah.
And his dad said, "Ah.
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他接着问：“什么叫惯性？” 爸爸说：“啊。
惯性嘛，就是科学家们
00:50
Inertia is the name that scientists give
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00:52
to the phenomenon of the ball
going to the back of the wagon."
going to the back of the wagon."
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给’球滚到车后面‘这种现象取的名字。
但事实上，没人明白这是怎么回事。“
00:55
(Laughter)
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00:57
"But in truth, nobody really knows."
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费曼后来在麻省理工学院和普林斯顿获得了学位，
01:00
Feynman went on to earn degrees
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他解决了挑战者号航天飞机失事事件的谜团，
01:02
at MIT, Princeton, he solved
the Challenger disaster,
the Challenger disaster,
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他最后获得了诺贝尔物理学奖
01:05
he ended up winning
the Nobel Prize in Physics
the Nobel Prize in Physics
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因他提出的描述粒子运动的费曼图。
01:08
for his Feynman diagrams, describing
the movement of subatomic particles.
the movement of subatomic particles.
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他把这归功于和父亲的那次对话，
01:12
And he credits that conversation
with his father as giving him a sense
with his father as giving him a sense
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让他认识到
最简单的问题可以将你带入人类知识的前沿，
01:16
that the simplest questions could carry
you out to the edge of human knowledge,
you out to the edge of human knowledge,
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而且那就是他想有所作为的地方。
01:21
and that that's where he wanted to play.
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他确实成功了。
01:23
And play he did.
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埃拉托斯特尼是亚历山大图书馆的第三任馆长，
01:25
Eratosthenes was the third librarian
at the great Library of Alexandria,
at the great Library of Alexandria,
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他为科学做出了很多贡献。
01:29
and he made many contributions to science.
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但他最为人们所铭记的成就
01:32
But the one he is most remembered for
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是由他在当图书馆馆长时收到的一封信开始的，
01:34
began in a letter that he received
as the librarian,
as the librarian,
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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）。
01:37
from the town of Swenet,
which was south of Alexandria.
which was south of Alexandria.
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信中的一个事实在埃拉托斯特尼的脑中挥之不去，
01:41
The letter included this fact
that stuck in Eratosthenes' mind,
that stuck in Eratosthenes' mind,
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写信的人说在夏至的正午时分，
01:44
and the fact was that the writer said,
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当他向一口深井望下去的时候，
01:46
at noon on the solstice,
when he looked down this deep well,
when he looked down this deep well,
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他可以看到井底的倒影，并发现他的头
01:49
he could see his reflection at the bottom,
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01:51
and he could also see
that his head was blocking the sun.
that his head was blocking the sun.
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正遮挡着太阳。
现在我告诉大家，哥伦布发现地球是圆的这个说法
01:54
I should tell you -- the idea
that Christopher Columbus
that Christopher Columbus
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纯属是胡说八道，根本不是真的。
01:57
discovered that the world
is spherical is total bull.
is spherical is total bull.
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事实上，所有受过教育的人都知道地球是圆的
01:59
It's not true at all.
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02:00
In fact, everyone who was educated
understood that the world was spherical
understood that the world was spherical
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这是自从亚里士多德时代起，而且亚里士多德本人
02:04
since Aristotle's time.
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还通过一个非常简单的观测证明过这个说法。
02:05
Aristotle had proved it
with a simple observation.
with a simple observation.
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他注意到地球在月亮上的影子
02:07
He noticed that every time you saw
the Earth's shadow on the Moon,
the Earth's shadow on the Moon,
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是圆的，
而且唯一能够持续的产生圆形影子的形状
02:11
it was circular,
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02:12
and the only shape that constantly
creates a circular shadow
creates a circular shadow
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就是球体，证明完毕。地球是圆的。
02:15
is a sphere, Q.E.D. the Earth is round.
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但是没有人知道地球有多大，
02:18
But nobody knew how big it was
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直到埃拉托斯特尼看到这封信里描述的事实。
02:19
until Eratosthenes got
this letter with this fact.
this letter with this fact.
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他知道当时太阳在直射塞尼
02:23
So he understood that the sun
was directly above the city of Swenet,
was directly above the city of Swenet,
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因为向井底看的时候，一条垂直光线
02:26
because looking down a well,
it was a straight line
it was a straight line
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经过那个人正当着太阳的头部，直射到井底。
02:29
all the way down the well,
right past the guy's head up to the sun.
right past the guy's head up to the sun.
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埃拉托斯特尼还知道另一个事实。
02:33
Eratosthenes knew another fact.
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他知道在同一天的同一时间，
02:34
He knew that a stick stuck
in the ground in Alexandria
in the ground in Alexandria
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也就是夏至的正午，
02:37
at the same time
and the same day, at noon,
and the same day, at noon,
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在亚历山大插一根棍子，
02:40
the sun's zenith, on the solstice,
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从太阳投射的影子得知光线偏离轴线7.2度。
02:42
the sun cast a shadow that showed
that it was 7.2 degrees off-axis.
that it was 7.2 degrees off-axis.
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如果你知道一个圆周边，
02:49
If you know the circumference of a circle,
and you have two points on it,
and you have two points on it,
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在圆上取两个点，
只需要知道这两点之间的距离，
02:53
all you need to know is the distance
between those two points,
between those two points,
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然后就可以推算周长了。
02:56
and you can extrapolate the circumference.
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360度除以7.2等于50。
02:58
360 degrees divided by 7.2 equals 50.
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我知道这是个整数，这也让我对这个故事产生了怀疑
03:02
I know it's a little bit
of a round number,
of a round number,
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但它仍是个不错的故事，所以我们继续讲下去。
03:04
and it makes me suspicious
of this story too,
of this story too,
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03:06
but it's a good story,
so we'll continue with it.
so we'll continue with it.
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他需要知道塞尼和亚历山大之间的距离，
03:08
He needed to know the distance
between Swenet and Alexandria,
between Swenet and Alexandria,
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这个问题很好解决，因为埃拉托斯特尼很擅长地理。
03:11
which is good because Eratosthenes
was good at geography.
was good at geography.
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事实上，是他创造了地理这个词。
03:15
In fact, he invented the word geography.
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塞尼和亚历山大之间的路
03:17
(Laughter)
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03:19
The road between Swenet and Alexandria
was a road of commerce,
was a road of commerce,
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是一条商业之路，
商人们需要知道多久能到达目的地，
03:22
and commerce needed to know
how long it took to get there.
how long it took to get there.
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就有必要知道两地的确切距离，所以埃拉托斯特尼
03:25
It needed to know the exact distance,
so he knew very precisely
so he knew very precisely
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非常精确的知道两地之间距离500英里。
03:28
that the distance between
the two cities was 500 miles.
the two cities was 500 miles.
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再乘以50，得到25000，
03:31
Multiply that times 50, you get 25,000,
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03:34
which is within one percent
of the actual diameter of the Earth.
of the actual diameter of the Earth.
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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。
03:38
He did this 2,200 years ago.
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现在我们生活的时代
03:42
Now, we live in an age where
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03:44
multi-billion-dollar pieces of machinery
are looking for the Higgs boson.
are looking for the Higgs boson.
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有价值几十亿美金的机器用来寻找希格斯玻色子。
我们正在探究比光速传播更快的粒子，
03:48
We're discovering particles
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03:50
that may travel faster
than the speed of light,
than the speed of light,
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这一切科学探索成为可能
03:52
and all of these discoveries
are made possible
are made possible
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是依靠过去几十年来的科技进步。
03:55
by technology that's been developed
in the last few decades.
in the last few decades.
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但是在大部分人类历史上，
03:58
But for most of human history,
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我们不得不用自己的眼睛、耳朵和大脑来探索问题。
04:01
we had to discover these things using
our eyes and our ears and our minds.
our eyes and our ears and our minds.
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阿曼德·斐索是巴黎一名实验物理学家，
04:06
Armand Fizeau was
an experimental physicist in Paris.
an experimental physicist in Paris.
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他的专业领域是确认和完善他人的成果，
04:10
His specialty was actually refining
and confirming other people's results,
and confirming other people's results,
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这听上去似乎有点无足轻重。
04:15
and this might sound
like a bit of an also-ran,
like a bit of an also-ran,
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但事实上，这正是科学的精髓，
04:17
but in fact, this is the soul of science,
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因为没有一件事实不可以被独立证明。
04:19
because there is no such thing as a fact
that cannot be independently corroborated.
that cannot be independently corroborated.
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他很熟悉伽利略试图的实验
04:23
And he was familiar
with Galileo's experiments
with Galileo's experiments
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来判断光是否拥有速度。
04:26
in trying to determine
whether or not light had a speed.
whether or not light had a speed.
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伽利略精彩绝伦的实验室这样完成的
04:29
Galileo had worked out this
really wonderful experiment
really wonderful experiment
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他和助手各有一盏灯，
04:32
where he and his assistant had a lamp,
each one of them was holding a lamp.
each one of them was holding a lamp.
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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。
04:36
Galileo would open his lamp,
and his assistant would open his.
and his assistant would open his.
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他们的时机把握得很好。
04:39
They got the timing down really good.
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他们很清楚自己的时机。他们分别站在两个山顶上，
04:41
They just knew their timing.
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04:42
And then they stood at two hilltops,
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距离两英里，然后做同样的事情
04:44
two miles distant,
and they did the same thing,
and they did the same thing,
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按照伽利略的假设，如果光线拥有可识别速度，
04:47
on the assumption from Galileo
that if light had a discernible speed,
that if light had a discernible speed,
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他就会注意到从助手那里返回光线的延时。
04:50
he'd notice a delay in the light
coming back from his assistant's lamp.
coming back from his assistant's lamp.
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但对于伽利略来讲，光线实在是太快了，
04:53
But light was too fast for Galileo.
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当他假设光速大约是声速的10倍时，
04:56
He was off by several orders
of magnitude when he assumed
of magnitude when he assumed
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他少说了好几个数量级。
04:58
that light was roughly ten times
as fast as the speed of sound.
as fast as the speed of sound.
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斐索很清楚这个实验。他住在巴黎，
05:02
Fizeau was aware of this experiment.
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05:04
He lived in Paris, and he set up
two experimental stations,
two experimental stations,
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于是他在那建立了两个实验站点，
大约相距5.5英里。
05:09
roughly 5.5 miles distant, in Paris.
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他解决了伽利略的问题，
05:12
And he solved this problem of Galileo's,
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而且他的实验器材相对来讲十分普通，
05:14
and he did it with a really relatively
trivial piece of equipment.
trivial piece of equipment.
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他就是用的这个。
05:19
He did it with one of these.
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我要把这个遥控器先放在一边，
05:21
I'm going to put away
the clicker for a second
the clicker for a second
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因为我要让你们的大脑也活跃起来。
05:23
because I want to engage
your brains in this.
your brains in this.
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这是一个齿轮，有一串凹槽，
05:25
So this is a toothed wheel.
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05:27
It's got a bunch of notches
and it's got a bunch of teeth.
and it's got a bunch of teeth.
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还有一串轮齿。
这就是斐索发送离散脉冲光的方法。
05:30
This was Fizeau's solution
to sending discrete pulses of light.
to sending discrete pulses of light.
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他将一束光线放在其中一个凹槽后面。
05:33
He put a beam behind one of these notches.
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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
05:35
If I point a beam
through this notch at a mirror,
through this notch at a mirror,
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这束光线由镜面反射回来
05:39
five miles away, that beam
is bouncing off the mirror
is bouncing off the mirror
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通过这个凹槽回到我这里。
05:41
and coming back to me through this notch.
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但当他快速转动齿轮时，有趣的现象发生了
05:44
But something interesting happens
as he spins the wheel faster.
as he spins the wheel faster.
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他注意到就好像是有一扇门在阻挡着
05:47
He notices that it seems
like a door is starting to close
like a door is starting to close
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返回他视野的光线
05:50
on the light beam
that's coming back to his eye.
that's coming back to his eye.
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为什么会这样？
05:53
Why is that?
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这是因为光线返回的时候
05:55
It's because the pulse
of light is not coming back
of light is not coming back
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通过的不是同一个凹槽。实际上，光线撞到了一个轮齿上。
05:57
through the same notch.
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05:59
It's actually hitting a tooth.
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当他把齿轮转得足够快的时候
06:00
And he spins the wheel fast enough
and he fully occludes the light.
and he fully occludes the light.
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光线被完全阻挡了
然后，根据两个实验站点的距离
06:05
And then, based on the distance
between the two stations
between the two stations
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06:08
and the speed of his wheel
and the number of notches in the wheel,
and the number of notches in the wheel,
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和齿轮的转速以及齿轮上凹槽的数量
他计算出了光的速度，和真实的光速只有百分之二的误差。
06:11
he calculates the speed of light
to within two percent of its actual value.
to within two percent of its actual value.
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而他在1849年就做到了。
06:16
And he does this in 1849.
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这就是我从事科学研究的原因。
06:21
This is what really gets me
going about science.
going about science.
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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。
06:23
Whenever I'm having trouble
understanding a concept,
understanding a concept,
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06:26
I go back and I research
the people that discovered that concept.
the people that discovered that concept.
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我要看看他们是如何理解这个概念的。
06:29
I look at the story of how
they came to understand it.
they came to understand it.
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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
06:31
What happens when you look
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06:33
at what the discoverers
were thinking about
were thinking about
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你就会明白
06:35
when they made their discoveries,
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06:37
is you understand that
they are not so different from us.
they are not so different from us.
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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
06:42
We are all bags of meat and water.
We all start with the same tools.
We all start with the same tools.
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我喜欢这种把不同的科学分支称为学科领域的说法，
06:46
I love the idea that different branches
of science are called fields of study.
of science are called fields of study.
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大多数人认为科学就是一个封闭的黑匣子
06:50
Most people think of science
as a closed, black box,
as a closed, black box,
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实际上它却是一片广阔天地
06:53
when in fact it is an open field.
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我们都是探险家。
06:56
And we are all explorers.
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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
06:58
The people that made these discoveries
just thought a little bit harder
just thought a little bit harder
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思考得更认真一点，并且他们的好奇心更多一点罢了，
07:01
about what they were looking at,
and they were a little bit more curious.
and they were a little bit more curious.
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他们的好奇心改变了人们看世界的方法，
07:05
And their curiosity changed the way
people thought about the world,
people thought about the world,
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进而改变了这个世界。
07:08
and thus it changed the world.
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他们改变了世界，你们大家也可以。
07:10
They changed the world, and so can you.
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谢谢。
07:14
Thank you.
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07:15
(Applause)
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（掌声）
ABOUT THE SPEAKER
Adam Savage - Maker, critical thinkerAdam Savage is an internationally renowned television producer, host and public speaker.
Why you should listen
Adam Savage's mother is a psychologist; his father was a celebrated artist, painter and filmmaker. From the youngest age they encouraged his flights of fancy. Savage has been a paperboy, a projectionist, juggler, unicycle rider, sculptor, graphic designer, scenic painter, robot builder, welder, carpenter, machinist, prop maker, toy designer, actor, writer, executive producer and director. He spent six years in theater and 10 years in commercial and film special effects working for clients such as Nike, Corning, Hershey's, and Coca-Cola, and films like Star Wars, The Matrix films, A.I., Space Cowboys, Terminator 3 and Galaxy Quest.
Savage has built everything from theater sets to miniature particle accelerators. From spaceships to animatronic arms. He's made Rube Goldberg machines, hand props and spacesuits. His online videos have generated over 230 million page views. He's written for Popular Mechanics, the Wall Street Journal and Wired Magazine, among others. His program "Mythbusters" produced 270 episodes that aired in over 100 countries for 14 years. Adam shares his builds, his love for movie props and costumes, and passion for the transformative power of making on his award winning website Tested.com. He lives in San Francisco with his wife Julia, his twin boys Thing1 and Thing2, and two amazing dogs.
(Photo: Michael Shindler)
Adam Savage | Speaker | TED.com