That like people, no two snowflakes are exactly alike.

就像人，沒有兩片雪花會一模一樣。

But is that really true?

但這是真的嗎？

Their intricate beauty is so delicate… so fleeting.

它們的細緻美麗是很纖弱的，如此地稍縱即逝。

It's made them one of nature's great mysteries.

這讓雪花成為自然的大秘密之一。

But that incredible complexity actually comes from very simple building blocks.

但這鬼斧神工的作品，其實構造非常簡單。

High up in the clouds, snowflakes begin as water vapor.

在高高的雲層裡，雪花最初是從水蒸氣開始的。

Water molecules whiz around, bouncing off of each other.

水分子到處亂撞，在彼此間彈來彈去。

When the temperature cools, the molecules slow down and start sticking to one another.

當溫度降下來，水分子會慢下來，開始與鄰居結合在一起。

They form a hexagon: six-point symmetry, the core structure of a snowflake.

最後會形成六角形：六角對稱圖形，雪花的核心架構。

As each one grows, it builds on that basic geometry, creating a crystal lattice.

隨著時間，雪花們以此基礎架構生長，形成一個水晶體。

That's why you tend to find snowflakes with six arms.

這就是你會發現雪花都是六角形的原因。

Not five, not seven.

不是五角形，或七角形。

From there, the variety just explodes.

但從這邊，變化就出現了。

The shapes are practically infinite.

雪花基本上有無限種形狀。

So what are the chances of finding two snow crystals that look exactly the same?

那找到兩片一模一樣的雪花的機率有多少？

In his lab at Caltech, Physics professor Ken Libbrecht has figured out how to solve that mystery.

物理教授 Ken Libbrecht 在他於 Caltech 的實驗室解開了這個謎題。

Inside a chamber, he makes snowflakes from scratch…

在實驗室裡，他從頭製造起雪花...

He starts with humid air, and drops the temperature until ice crystals start to form.

從潮濕空氣開始，他調低溫度，直到開始形成冰晶。

When they get heavy enough they fall.

當它們變得夠重，就會掉下來。

He catches them on a chilled plate, where he can watch them grow using time-lapse photography.

他用一個冷凍的盤子接住它們，並用縮時攝影記錄他們的生長。

As he boosts the humidity, arms begin to extend out from the corners.

當他提高溼度，雪花便開始生長。

If he cools the air even more, branches shoot off the arms.

若他調低空氣溫度，生長便會更加快速。

Libbrecht can create a bunch of crystals on the same plate.

Libbrecht 可以在這個盤子上製造一堆雪花。

Like these two, they're growing in exactly the same conditions.

就像這兩個，它們在完全相等的環境下生長。

And look!

看！

Twins!

是雙胞胎！

But these perfect copies only exist here… in the lab.

但這種雙胞胎只會出現在這裡，實驗室裡。

Outside up in the clouds it's unpredictable.

在外面雲層上，一切都太不可預料了。

The temperature, humidity and air pressure are constantly changing.

溫度、濕度與壓力都不斷在改變。

Each snowflake takes its own path as it falls to earth.

每片雪花落下的路徑也都不同。

And that solo flight means they all grow a little... differently.

每片雪花獨特的旅程也代表，它們都會長得有點不一樣。

So each one really is unique, shaped by its own individual journey through the world.

所以每片雪花真的都是獨特的，在它降落的旅程中慢慢塑形。

Hey guys, it's Lauren.

嗨，我是 Lauren。

We've got a few more tiny mysteries for you.

我們還準備了一些小祕密要分享給你。

Find out how roly polies ventured out from the ocean to conquer your backyard.

來看看鼠婦是怎麼遠渡重洋，跑來征服你家院子的。

Or how just one handful of sand can tell you the history of the entire planet.

或只要一把沙子，其實就能知道地球的歷史。

And while you're at it, share us!

當你在欣賞的時候，記得分享！

See you next time.

下次見！