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, that you could only see things that were red and that everything else was completely invisible to you.
想像一下，比如说你只能看见红色的东西，而其它所有东西对你来说都是隐形的。
As it turns out, that's how you live your life all the time
实际上，我们一直都是这样生活的，
because your eyes can only see a minuscule part of the full spectrum of light.
因为我们的眼睛只能看到全光谱中微不足道的一部分。
Different kinds of light are all around you everyday but are invisible to the human eye,
我们每天都被不同的色彩所包围，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, to the microwaves that heat up your food.
到医生用来观察人身体内部的X光线，还有可用来加热食物的微波。
In order to understand how these can all be light, we'll need to know a thing or two about what light is.
为了能够理解它们是如何被叫做光的，我们需要知道一些关于什么是光的问题。
Light is electromagnetic radiation that acts like both a wave and a particle.
光就是电磁辐射，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, waves that crash on the shore one right after the other,
波浪本身有大小之分，波浪就是一波一波冲上海岸，
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, and how often it comes by is called its frequency.
波浪的大小叫作波长，波浪多久重复一次叫做波的频率。
Imagine being a boat in that ocean, bobbing up and down as the waves go by.
想像你坐在海上的一艘船里，船随着波浪上下起伏。
If the waves that day have long wavelengths, they'll make you bob only so often, or at a low frequency.
如果那天赶上的波浪有较长的波长，那么海浪只会让船偶尔上下起伏，或者说以较低的频率。
If the waves, instead, have short wavelengths, they'll be close together,
然而，相反的，如果是波长很短的波浪，波浪之间会靠的很紧，
and you'll bob up and down much more often, at a high frequency.
然后你就会感觉船在明显的上下浮动，这就是以很高的频率。
Different kinds of light are all waves, they just have different wavelengths and frequencies.
不同种类的光都是光波，只不过他们有不同的波长和频率的区别。
If you know the wavelength or frequency of a wave of light, you can also figure out its energy.
如果你知道一种光波的波长或者频率，那么你就可以知道这个光波的能量。
Long wavelengths have low energies, while short wavelengths have high energies.
波长长的光波有很低的能量，然而波长短的光波有很高的能量。
It's easy to remember if you think about being in that boat.
如果你想到自己在那艘船上，这个记起来就很容易。
If you were out sailing on a day with short, choppy waves,
如果有天你去航海，那天有波涛汹涌的海浪，
you'd probably be pretty high energy yourself, running around to keep things from falling over.
你可能会消耗很多能量，避免被东西砸到而四处跑。
But on a long wavelength sea, you'd be rolling along, relaxed, low energy.
但是在一个长波长的海面上，你只会晃一晃，会感觉很放松，不怎么消耗能量。
The energy of light tells us how it will interact with matter, for example, the cells of our eyes.
光的能量告诉了我们它是如何和事物相互联系的。举个例子来说，我们眼睛的细胞。
When we see, it's because the energy of light stimulates a receptor in our eye called the retina.
当我们看见事物的时候，是由于光的能量刺激了我们眼睛的感觉器官，这个感觉器官叫做视网膜。
Our retina are only sensitive to light with a very small range in energy, and so we call that range of light visible light.
我们的视网膜只对一个比较小范围内的能量比较敏感，所以那一范围能量的光被叫做可见光。
Inside our retina are special receptors called rods and cones.
在我们的视网膜里有很多特别的感觉器官，叫做视杆细胞和视锥细胞。
The rods measure brightness, so we know how much light there is.
视杆细胞测量亮度，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 because different cones are sensitive to different energies of light.
视锥细胞负责我们看到的光的颜色，因为不同的视锥细胞对不同能量的光感知度不同。
Some cones are more excited by light that is long wavelength and low energy,
有一些视锥细胞对那些波长很长和能量很低的光很敏感，
and other cones are more excited by short wavelength, high-energy light.
还有一些视锥细胞对波长短能量高的光更敏感。
When light hits our eye, the relative amount of energy each cone measures signals our brain to perceive colors.
当光照射到我们的眼睛的时候，每一个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。
The rainbow we perceive is actually visible light in order of its energy.
我们看见的彩虹事实上就是可见光根据本身能量的排序。
At one side of the rainbow is low-energy light we see as red, and at the other side is high-energy light we see as blue.
在彩虹的最上边是我们看到低能量的红色的光，另外一边是能量较高、我们所看到的蓝光。

If light shines on us that has an energy our retina can't measure, we won't be able to see it.
如果光照着我们，那就有我们视网膜无法识别的能量，我们就不可能看见它。
Light that is too short wavelength or high energy gets absorbed by the eye's surface before it can even get to the retina,
波长太短或者能量太高的光波，会在它到达视网膜之前被眼睛的表面吸收，
and light that is too long wavelength doesn't have enough energy to stimulate our retina at all.
那些波长很长的光波根本没有能够刺激我们视网膜的能量。
The only thing that makes one kind of light different from another is its wavelength.
光和光之间唯一的不同点就是它的波长。
Radio waves have long wavelengths, while x-rays have short wavelengths.
无线电波有很长的波长，然而X光射线有很短的波长。
And visible light, the kind you can actually see, is somewhere in between.
可见光，就是你现实可以看见的光，波长范围介于这两者之间。
Even though our eyes can't detect light outside of the visible range,
虽然我们的眼睛无法看到可见光范围之外的光，
we can build special detectors that are stimulated by these other wavelengths of light, kind of like digital eyes.
但我们可以创造特殊的探测器，它由其他波长的光刺激，有点像数字眼。
With these devices, we can measure the light that is there, even though we can't see it ourselves.
这些器件可以帮助我们感应那些我们自己无法看见的光。
So, take a step back and think about all of this for a moment.
所以，退一步，先想想这一切。
Even though they seem different, the warmth you feel from a crackling fire is the same as the sun shining on you on a beautiful day,
即使他们是不同的，从一堆劈啪作响的火焰中感受的温暖和在一个美好的天气中太阳晒着你时是一样温暖，
the same as ultraviolet light you put on sunscreen to protect yourself from,
一样的还有紫外线，我们涂防晒霜来保护自己不受它的伤害，
the same thing as your TV, your radio, and your microwave.
一样的事物还有你的电视，你的收音机还有你的微波炉。
Now, those examples are all things here on Earth, things you experience in your everyday life,
这些例子都是地球上的事物，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, you probably think of being able to see the stars shining with your own eyes,
试想一下黑夜的天空，你也许觉得是你眼睛使你看到星星在闪，
but that's just visible light, which you now know is only a tiny part of the full spectrum.
但那只是可见光，现在你该知道那只是全光谱中很小的一部分光。
If we had to draw the universe and could only use visible light, it would be like having only one crayon -- pretty sad.
如果我们只可以用可见光来画整个宇宙，这就好像只有一种蜡笔。那很可悲。
To see the universe in its full spectrum, we need to have the right eyes,
为了能看见全光谱中的宇宙，我们必须要有合适的眼睛，
and that means using special telescopes that can help us see beyond visible light.
这就意味着用特殊的望远镜来帮助我们看到可见光之外的光。
You've probably heard of the Hubble Space Telescope and seen its beautiful pictures taken in visible and ultraviolet light.
也许你听说过哈勃太空望远镜，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 that there are 20 space telescopes in orbit, missions that can each see part of the full spectrum of light.
但是你也许不知道在轨道上有20个太空望远镜，每一个望远镜的任务是看到全光谱的不同部分。
With telescopes acting as our virtual eyes, both in space and here on Earth, we can see some amazing things.
让望远镜作为我们虚拟的眼睛，在外太空和地球，我们可以看到一些神奇的事物。
And the coolest thing of all, no matter the wavelength or energy,
然而最酷的事情是，不考虑波长和能量，
the light that we see out in the distant universe is the same thing as the light that we can experience and study here on Earth.
我们看见的遥远宇宙的光，和我们体验及在这里学习的地球上的光是一样的。
So, since we know the physics of how x-ray, ultraviolet light, or microwaves work here,
所以，由于我们知道了X射线，紫外线，微波在地球上的物理工作原理，
we can study the light of a distant star or galaxy and know what kinds of things are happening there too.
我们可以学习研究一个遥远的恒星或星系的光，然后也可以知道在那里发生了什么事。
So, as you go about your daily life, think beyond what your eyes can and can't see.
所以在日常生活中，在你所看到和看不到的时候去思考。
Knowing just a little bit about the natural world can help you perceive the full spectrum around you all the time.
只是了解关于自然世界的一点点，就可以帮助你一直感受身边的全光谱世界。