One sheet of paper is roughly half a million atoms thick.

比一張紙大約薄了五十萬分之一

Volume-wise, one atom is as small compared

體積觀點來看，把一個原子比喻成一顆蘋果

to an apple as that apple is to the entire earth.

如同一顆蘋果對比於整個地球

So you might be surprised to learn that

所以你應該會訝異得知

chemists can actually see atoms.

化學家能確實看到原子

Not with their eyes.

不是透過他們的雙眼

With incredibly precise tools.

而是令人難以置信地精密工具

[Legends of Chemistry intro]

[化學傳奇介紹]

The idea of atoms stretches back to ancient Greece,

原子這個想法可以延伸到古希臘

when the philosopher Democritus declared that

當哲學家德謨克利特宣稱

all matter is made of tiny particles.

所有事物都由微小粒子所組成的

The philosopher Plato even decided—wrongly—that

哲學家柏拉圖甚至無疑（現在看來是錯誤）地說

different substances had differently

不同物質擁有不同

shaped atoms, like pyramids or cubes.

形狀的原子，像是三角錐體或立方體

The first modern evidence for atoms appeared

第一個原子的近代證據發現

in the early 1800s, when British chemist

於1800年早期，當時還是大不列顛的化學家

John Dalton discovered that chemicals always

約翰．道耳頓發現化合物總是

contain whole-number ratios of elements.

含有整數倍比例的元素

That’s why it’s H2O and not H2.4O or H√17O.

這就是為什麼它是H2O而不是H2.4O或H√17O

The reason for these whole numbers, Dalton

由於這些都是整數，道耳頓

suggested, was because you can’t have a half

認為，因為你無法找到半顆原子

an atom or point-two atoms, only whole atoms.

或0.2顆原子，只有完整的原子

It’s hard to imagine chemistry today without Dalton’s insight.

難以想像現今化學沒有道耳頓的觀點

But it was actually controversial in its day.

但它實際上爭論了好些日子

Why?

這是為何？

Because chemists couldn’t see atoms.

因為化學家無法用雙眼看到原子

Many considered them like negative numbers

有很多值得考慮的，像是負整數

or ideal gases: useful for calculating things,

或理想氣體：計算東西能幫上忙

but not existing in the real world.

但是不存在於真實世界

Even Dmitri Mendeleev, father of the periodic table,

甚至元素週期表之父：德米特里．門得列夫

refused to believe in atoms for many years.

拒絕去相信原子論很多年

Why didn’t chemists just look for atoms under microscopes?

為何化學家不把原子放到顯微鏡下觀察就好？

To see something under a microscope, the wavelength

在顯微鏡下想看見東西，

of light you’re shining through the microscope

透過顯微鏡觀看物體發出的光波長

can't be larger than whatever you’re looking at.

無論你看的是什麼要落於可見光波長

Unfortunately, visible light is thousands of times bigger than atoms.

不幸地，可見光的波長比原子大了千倍以上

So chemists had to wait for light with

所以化學家必須直到光有

shorter wavelengths, like x-rays.

更短的波長，像是X射線

X-rays were discovered in the 1890s by

X射線在1890年被發現，由

German scientist Wilhelm Röntgen, who

德國科學家威廉．倫琴

realized that photographs taken with x-rays

他明白了使用X射線攝影的方法

allowed him to see through objects.

能讓他看穿透物體

Roentgen thought he’d gone insane when

當倫琴看見這個，為之瘋狂

he saw this, but today we’re all familiar with

但是在今天的我們都熟悉

x-rays from trips to the dentist and doctor.

X射線，透過看牙醫和醫生

Chemists don’t use x-rays to see through things.

化學家們不是使用X射線去看穿東西

Instead, they bounce x-rays off things like crystals,

反而，他們對東西彈射X射線像水晶

which are solids with layers of atoms. When x-rays

晶體是一層層原子的固體。當X射線

hit an atom in a crystal, they bounce back.

打中一個水晶中的原子，他們彈射回去

Others slip through and bounce off the second layer down.

其它的滑行穿過，在第二層反彈

Or the third layer, or deeper.

或第三層，或更深入的層

After being reflected, these x-rays strike a detector

反射過後，這些X射線擊中偵測器的

screen, like the ball bouncing back in Pong.

螢幕，像是在乓（桌球遊戲）中彈回來的球

And based on where the x-rays came from

基於X射線照射到的地方

and how they interacted with each other,

和他們如何互相影響彼此

scientists can work backward and figure out

科學家能反推和找出

the arrangement of atoms in the crystal.

水晶中的原子排列

This reflection and interaction of light rays is called diffraction.

這個反射和光射線的相互作用稱為繞射

X-ray diffraction, sometimes called x-ray

X射線繞射，有時候稱為X射線

crystallography, has led to dozens of

晶體學，從1920年開始導致一大堆的

Nobel Prizes for chemists since the 1920s.

諾貝爾化學獎得主產生

It also led to one of the biggest discoveries in science

它也導致科學史上最重大的發現

history, the structure of DNA. James Watson and

DNA的結構，詹姆斯．華生和

Francis Crick get credit nowadays, but they based

佛朗西斯．克里克得到當今榮譽，但是他們是基於

their work on the work of Rosalind Franklin,

他們是在研究羅莎琳．富蘭克林的研究成果

a crystallographer in England.

她是一位在英格蘭的晶體學家

She began taking x-ray pictures of DNA in 1952,

在1952年，她開始拍攝DNA的X射線照片

and Watson’s glimpse of one picture — photograph 51.

華生瞥見其中一張照片-照片51

— was the vital clue in determining that

它是重大線索決定了

DNA was a double helix.

DNA是一個雙螺旋結構

This incident remains controversial today

今天這個意外至今仍然爭論

Because Franklin never gave Watson

因為富蘭克林從未給予沃森

permission to view photograph 51.

許可去查看照片51（實際是他同事給他看的）

If x-rays let chemists peer at the structure of atoms,

如果X射線能讓化學家們看到原子的結構

scanning tunneling microscopes

掃描式通道顯微鏡

finally revealed atoms themselves.

終於讓原子顯現出他們自己

Rather than bounce light off something,

而不是光線彈跳在某個東西

an STM runs a sharp needle over its surface.

一台掃描式通道顯微鏡驅動一根尖的針狀物在它的表面

It’s like chemical Braille, except

它就像化學版布拉耶點字法（盲文）

the tip never quite touches.

尖端從不完全接觸

As the tip moves along the surface, scientists

當尖端沿著表面移動，科學家們

can reconstruct the atomic landscape — making

能重建原子的圖像

individual atoms visible at last in the early 1980s.

讓個別的原子可被看見，至少在1980年早期

Lo and behold, the atoms weren’t Plato’s cubes

你瞧，原子形狀不是柏拉圖的立方體

and pyramids, but spheres of different sizes.

和三角錐體，而是不同大小的球體

By 1989 a few scientists had even adapted

在1989年，一些科學家開始採用

STM technology to manipulate single

掃描式通道顯微鏡技術運用在單一

xenon atoms and spell out words.

氙原子和拼寫出來單字

We’ll let you guess what company they worked for.

我們讓你猜猜他們為哪個公司工作

Also in 1989, the chemist Ahmed Zewail moved

也再1989年，化學家亞米德·齊威爾

beyond looking at stationary atoms and

進一步超過觀看靜態的原子

developed tools to see atoms in action.

開發工具去觀察原子的活動

Zewail wanted to study how atoms break bonds

齊威爾想要研究原子如何突破束縛

and swap partners during reactions.

在化學反應時交換原子

So he developed the world’s fastest camera,

所以他開發出世界上最快的照相機

which shoots pulses of laser light a few femtoseconds

發射雷射脈波在幾個飛秒長的時間

long—a few billionths of a microsecond.

是幾個毫秒的十億分之一

If you stretched one femtosecond to a full second,

如果你展開一飛秒到一秒上

it would be like stretching a single

它就像是展開一秒

second out to 32 million years.

對三千二百萬年

While Zewail’s laser flashed like a strobe, his camera snapped pictures.

當齊威爾的雷射閃光像閃控，透過相機用快照拍攝照片

Zewail then ran the pictures together

齊威爾將相片收集在一起

like a slow-motion replay.

像慢動作重播

Since then femtochemistry had provided insight into

從那時以來飛秒化學提供洞察力在

everything from ozone depletion to the workings

每件事情上，從臭氧用盡到

of the human retina. Zewail won a Nobel Prize

人類視網膜的活動。在1999年，齊威爾獲得諾貝爾獎

in chemistry for his work in 1999.

紀念他在化學的成就

The ancient Greeks dreamed up fanciful shapes for atoms.

古希臘對於原子的形狀充滿幻想

But it took 2,400 years before scientists could see

但它花了二千四百年的時間，直到科學家能夠真實看見

them for real and study their behavior.

他們和研究它們的行為

Seeing truly is believing for human beings, and it was

對人類來說眼見為憑，它是

chemists and other scientists who fulfilled this need

化學家和其它科學家實現這個需求

and finally revealed what our universe is made of.

最後展示我們的宇宙是由什麼組成

Thanks for watching chemheads.

感謝你收看chemheads

Be sure to check out other videos in the

你也可以收看其它的影片在

Legends of Chemistry series, Like the Woman

化學傳奇系列，像

Who Saved the U.S. Space Program, and

拯救美國的太空計劃的女人和

the crafty scientists who tricked the Nazis.

欺詐納粹的狡猾科學家

Don’t forget to hit the subscribe button

別忘了去點擊訂閱按鈕

for weekly chemistry awesomeness.

收看每週的化學大驚奇