Light waves, visible and invisible

可见的和不可见的光波- 卢西阿尼 沃克维茨

翻译人员: xuanyu shi 校对人员: Qiwen Lu

What if you could only see one color?

如果你只能看见一种颜色那会怎么样？

Imagine, for instance,

想像一下，比如说

that you could only see things that were red

你只能看见红色的东西

and that everything else

而其它所有东西

was completely invisible to you.

对你来说都是隐形的

As it turns out,

实际上，

that's how you live your life all the time

我们一直都是这样生活的

because your eyes can only see

因为我们的眼睛只能看到

a minuscule part of the full spectrum of light.

全光谱中微不足道的一部分。

Different kinds of light are all around you everyday

我们每天都被不同的色彩所包围

but are invisible to the human eye,

但它们对人眼都是看不见的。

from the radio waves that carry your favorite songs,

从携带你最爱歌曲的无线电波，

to the x-rays doctors use to see inside of you,

到医生用来观察人身体内部的X光线，

to the microwaves that heat up your food.

还有可用来加热食物的微波。

为了能够理解

In order to understand

how these can all be light,

它们是如何被叫做光的，

we'll need to know a thing or two

我们需要知道一些

about what light is.

关于什么是光的问题。

Light is electromagnetic radiation

光就是电磁辐射

that acts like both a wave and a particle.

它既具有波的性质又有粒子的性质。

Light waves are kind of like waves on the ocean.

光波和海浪有些相似。

There are big waves and small waves,

波浪本身有大小之分，

waves that crash on the shore

波浪就是

one right after the other,

一波一波冲上海岸，

and waves that only roll in every so often.

而且波浪只有在偶尔才会翻滚。

The size of a wave is called its wavelength,

波浪的大小叫作波长，

and how often it comes by

波浪多久重复一次

is called its frequency.

叫做波的频率。

Imagine being a boat in that ocean,

想像你坐在海上的一艘船里

bobbing up and down as the waves go by.

船随着波浪上下起伏

If the waves that day have long wavelengths,

如果那天赶上的波浪有较长的波长

they'll make you bob only so often,

那么海浪只会让船偶尔上下起伏，

or at a low frequency.

或者说以较低的频率。

If the waves, instead, have short wavelengths,

然而，相反的，如果是波长很短的波浪，

they'll be close together,

波浪之间会靠的很紧，

and you'll bob up and down much more often,

然后你就会感觉船在明显的上下浮动，

at a high frequency.

这就是以很高的频率。

Different kinds of light are all waves,

不同种类的光都是光波，

they just have different wavelengths and frequencies.

只不过他们有不同的波长和频率的区别。

If you know the wavelength or frequency

如果你知道一种光波的波长或者频率

of a wave of light,

you can also figure out its energy.

那么你就可以知道这个光波的能量。

Long wavelengths have low energies,

波长长的光波有很低的能量，

while short wavelengths have high energies.

然而波长短的光波有很高的能量。

It's easy to remember

这个记起来很容易，

if you think about being in that boat.

如果你想到自己在那艘船上，

If you were out sailing on a day

如果有天你去航海

with short, choppy waves,

那天有波涛汹涌的海浪，

you'd probably be pretty high energy yourself,

你可能会消耗很多能量，

running around to keep things from falling over.

避免被东西砸到而四处跑。

But on a long wavelength sea,

但是在一个长波长的海面上，

you'd be rolling along, relaxed,

你只会晃一晃，会感觉很放松

low energy.

不怎么消耗能量。

光的能量告诉了我们

The energy of light tells us

how it will interact with matter,

它是如何和事物相互联系的。

for example, the cells of our eyes.

举个例子来说，我们的眼细胞。

When we see, it's because the energy of light

当我们看见事物的时候，是由于光的能量

stimulates a receptor in our eye

刺激了我们眼睛的感觉器官

called the retina.

这个感觉器官叫做视网膜。

Our retina are only sensitive to light

我们的视网膜只对

with a very small range in energy,

一个比较小范围内的能量比较敏感，

and so we call that range of light visible light.

所以那一范围能量的光被叫做可见光。

Inside our retina are special receptors

在我们的视网膜里有很多特别的感觉器官

called rods and cones.

视杆细胞和视锥细胞。

The rods measure brightness,

视杆细胞测量亮度，

so we know how much light there is.

所以我们可以知道有多少亮光。

The cones are in charge of what color of light we see

视锥细胞负责我们看到的光的颜色

because different cones are sensitive

因为不同的视锥细胞对不同能量的光感知度不同。

to different energies of light.

Some cones are more excited by light

有一些视锥细胞对那些波长很长和能量很低的光很敏感，

that is long wavelength and low energy,

and other cones are more excited

还有一些视锥细胞对波长短能量高的光更敏感。

by short wavelength, high-energy light.

When light hits our eye,

当光照射到我们的眼睛的时候，每一个

the relative amount of energy each cone measures

视锥细胞测量到的能量多少就标志着我们大脑接收的颜色。

signals our brain to perceive colors.

The rainbow we perceive

我们看见的彩虹

is actually visible light in order of its energy.

事实上就是可见光根据本身能量的排序。

At one side of the rainbow

在彩虹的最上边

is low-energy light we see as red,

是我们看到低能量的红色的光，

and at the other side is high-energy light

另外一边是能量较高 我们所看到的蓝光。

we see as blue.

If light shines on us

如果光照着我们

that has an energy our retina can't measure,

那就有我们视网膜无法识别的能量

we won't be able to see it.

我们就不可能看见它。

Light that is too short wavelength or high energy

波长太短或者能量太高的光波

gets absorbed by the eye's surface

会在它到达视网膜之前

before it can even get to the retina,

被眼睛的表面吸收，

and light that is too long wavelength

那些波长很长的光波

doesn't have enough energy

根本没有能够刺激我们视网膜的能量。

to stimulate our retina at all.

The only thing that makes one kind of light

光和光之间唯一的不同点就是它的波长。

different from another is its wavelength.

Radio waves have long wavelengths,

无线电波有很长的波长，

while x-rays have short wavelengths.

然而X光射线有很短的波长。

And visible light, the kind you can actually see,

可见光，就是你现实可以看见的光，

is somewhere in between.

波长范围介于两者之间。

Even though our eyes can't detect light

虽然我们的眼睛无法看到

outside of the visible range,

光可见光范围之外的光，

we can build special detectors

我们可以创造特殊的探测器,

that are stimulated

它由其他波长的光刺激,

by these other wavelengths of light,

kind of like digital eyes.

有点像数字眼。

With these devices,

这些器件

we can measure the light that is there,

可以帮助我们感应那些

even though we can't see it ourselves.

我们自己无法看见的光。

So, take a step back and think about

所以，退一步，先想想这一切。

all of this for a moment.

Even though they seem different,

即使他们是不同的

the warmth you feel from a crackling fire

从 一堆劈啪作响的火焰中感受的温暖

is the same as the sun shining on you

和在一个美好的天气中太阳晒着你时是一样温暖

on a beautiful day,

the same as ultraviolet light

一样的还有紫外线，我们涂防晒霜来保护自己不受他的伤害

you put on sunscreen to protect yourself from,

the same thing as your TV,

一样的事物还有你的电视，

your radio,

你的收音机

and your microwave.

还有你的微波炉。

这些例子都是地球上的事物，

Now, those examples are all things here on Earth,

things you experience in your everyday life,

都是你每天要经历的事情。

but here's something even more amazing.

但是，这里还有一些更惊喜的事儿

Our universe gives off the full spectrum of light, too.

我们的宇宙也散发全光谱的光。

When you think of the night sky,

试想一下黑夜的天空

you probably think of being able

你也许觉得是你眼睛

to see the stars shining with your own eyes,

使你看到星星在闪，

but that's just visible light,

但那只是可见光，

which you now know is only a tiny part

现在你该知道那只是

of the full spectrum.

全光谱中很小的一部分光。

If we had to draw the universe

如果我们只可以用

and could only use visible light,

可见光来画整个宇宙

it would be like having only one crayon --

这就好像只有一种蜡笔。

pretty sad.

那很可悲。

To see the universe in its full spectrum,

为了能看见全光谱中的宇宙，

we need to have the right eyes,

我们必须要有合适的眼睛。

and that means using special telescopes

这就意味着用特殊的望远镜

that can help us see beyond visible light.

来帮助我们看到可见光之外的光。

You've probably heard of the Hubble Space Telescope

也许你听说过哈勃太空望远镜，

and seen its beautiful pictures

taken in visible and ultraviolet light.

也看到过它用可见光和紫外光拍摄的惊艳的照片。

But you might not know

但是你也许不知道

that there are 20 space telescopes in orbit,

在轨道上有20个太空望远镜，

missions that can each see part

每一个望远镜的任务是看到全光谱的不同部分。

of the full spectrum of light.

With telescopes acting as our virtual eyes,

让望远镜作为我们虚拟的眼睛，

both in space and here on Earth,

在外太空和地球，

we can see some amazing things.

我们可以看到一些神奇的事物。

And the coolest thing of all,

然而最酷的事情是

no matter the wavelength or energy,

不考虑波长和能量，我们看见的遥远宇宙的光

the light that we see out in the distant universe

is the same thing as the light

和我们体验和在这里学习的地球上的光是一样的。

that we can experience and study here on Earth.

So, since we know the physics

所以，由于我们知道了X射线，紫外线，

of how x-ray,

ultraviolet light,

微波在地球上的物理工作原理​​

or microwaves work here,

we can study the light of a distant star or galaxy

我们可以学习研究一个遥远的恒星或星系的光

and know what kinds of things

然后也可以知道在那里发生了什么事。

are happening there too.

So, as you go about your daily life,

所以在日常生活中，

think beyond what your eyes can and can't see.

在你所看到和看不到的时候去思考，

Knowing just a little bit about the natural world

只是了解关于自然世界的一点点

can help you perceive the full spectrum

就可以帮助你一直

感受身边的全光谱世界。

around you all the time.