To understand the phenomenon of color, it helps to think about light as a wave.

要理解色彩原理，可以把光想成一種波。

But, before we get to that, let's talk a little bit about waves in general.

在討論色彩之前，我們先來談談「波」這個概念。

Imagine you're sitting on a boat on the ocean, watching a cork bob up and down in the water.

想象你正在海上，坐在船上看著軟木塞在海裡上下漂動。

The first thing you notice about the motion is that it repeats itself.

你會先注意到它不停重覆著同樣的動作。

The cork traces the same path over and over again... up and down, up and down.

軟木塞沿著相同路徑，一次又一次地上下擺動。

This repetitive or periodic motion is characteristic of waves.

這個重覆，或稱為「週期」的動作就是波的特徵。

Then you notice something else...

然後你又注意到了另一件事……

using a stopwatch, you measure the time it takes for the piece of cork to go over its highest position down to its lowest and then back up again.

你用秒錶測量一塊軟木塞從最高點下降到最低點， 再回到最高點來回所需的時間。

Suppose this takes two seconds.

假設需要兩秒鐘。

To use the physics jargon, you've measured the period of the waves that cork is bobbing on.

用物理術語來說，你測量到的是乘載軟木塞載波浪的週期。

That is, how long it takes a wave to go through its full range of motion once.

週期指的就是「波」從最低點到最高點全程所需的時間。

The same information can be expressed in a different way by calculating the wave's frequency.

同樣的數據可以透過計算波的頻率來表示。

Frequency, as the name suggest, tells you how frequent the waves are.

頻率，就如這名詞所指，意指波浪多常擺動。

That is, how many of them go by in one second.

也就是說，一秒鐘有多少個波產生。

If you know how many seconds one full wave takes, then it's easy to work out how many waves go by in one second.

如果你知道一個完整的波需要花多少時間，就可以輕鬆算出一秒之內產生了多少「波」。

In this case, since each wave takes 2 seconds, the frequency is 0.5 waves per second.

在這種情況下，由於乘載軟木塞的波一次時間為 2 秒，所以其頻率為每秒 0.5 波。

So enough about bobbing corks... what about light and color?

講夠那上上下下的軟木塞了……光和顏色又是怎麼一回事？

If light is a wave, then it must have a frequency, right?

如果光是一種「波」， 那它勢必會有頻率，對吧？

Well... yes, it does.

沒錯，它有頻率。

And it turns out that we already have a name for the frequency of the light that our eyes detect.

事實上眼睛可偵測範圍的光頻已經有名字了。

It's called color.

那就是「顏色」。

That's right. Color is nothing more than a measure of how quickly the light waves are waving.

對，顏色指的就是光波波動的頻率。

If our eyes were quick enough, we might be able to observe this periodic motion directly, like we can with the cork and the ocean.

如果我們的眼睛能夠趕上光波，就能直接觀察它的週期運動，就像觀察軟木塞在海洋中波動一樣。

But the frequency of the light we see is so high, it waves up and down over 400 million million times a second that we can't possibly see it as a wave.

但我們所看見的光頻是之高，每秒鐘上下波動約 400 億億次，我們無法以波的形勢見到它。

But we can tell, by looking at its color, what its frequency is.

但我們可以透過觀察顏色得知其頻率。

The lowest frequency light that we can see is red and the highest frequency is purple.

肉眼可以見最低頻率光線是紅色，而最高頻率是紫色。

In between all the other frequencies form a continous band of color, called the visible spectrum.

在紅色與紫色之間， 其他頻率形成一個色彩的相續頻 稱為可見光譜。

So, what if you had a yellow pencil sitting on your desk?

所以，如果有一枝黃色鉛筆在桌上，那代表了什麼？

Well, the sun emits all colors of light, so light of all colors is hitting your pencil.

太陽會發出包含所有顏色的光， 而光照在了鉛筆上。

The pencil looks yellow because it reflects yellow light more than it reflects the other colors.

鉛筆看上去是黃色是因為比其它的顏色的光，它反射的黃光最多。

What happens to the blue, purple and red light?

那藍、紫、紅色的光去哪了？

They get absorbed and the energy they are carrying is turned into heat.

被吸收了，而它們的能量則被轉化成了熱量。

It's similar with objects of other colors.

其他顏色的物件亦是如此。

Blue things reflect blue light, red things reflect red light and so on.

藍色的東西反射藍光、紅色的東西反射紅光，以此類推。

White objects reflect all colors of light, while black things do exactly the opposite and absorb at all frequencies.

而白色物件反射了所有顏色的光，黑色的東西則完全相反，它吸收了所有的光頻。

This — by the way — is why it's uncomfortable to wear your favorite Metallica t-shirt on a sunny day.

這也是為什麼在大太陽下，穿著你最喜歡的 Metallica 樂團踢恤會這麼不舒服。