Why Can’t We See Air and Can A Fish See The Water?
We can only see objects when light falls into are eyes after being reflected from the objects.
Like this
The sunlight has seven colours. But the boy sees the flower as yellow.
Why is that? Because of the flower relicts only a yellow colour. Like this
Here this matter is looked green as it reflects only green colour.
Like the green leaves, which only reflects the green colour, like this
Think of any object which absorbs all the light which fall on that.
Can we see that object? No.
We can only see objects when light falls into are eyes after being reflected from the objects.
For this reason, we cannot see anything in the dark.
For another reason, we cannot see any matter if light cannot reflect from that object.
Simply, if any portions of light will not get a return from that matter then there will no reflected light.
And without the reflected portion of light, it will not reach our eyes and we will not able to see that.
Light has speed and it differs in a different medium.
Hereby the word medium, we indicate through which light can go through.
Like Air, any types of gages, water etc.
But the speed of light different in a different medium.
It is assumed that the speed of light in a vacuum is absolute.
When light passes from one medium to another the difference in speed of light is calculated through the refractive index. Here is a chart of the refractive index.
Here you can see that there is almost nil refraction when the light comes into the air through a vacuum.
For the living being who survives of the earth surrounded by air.
For us, there is almost nil reflection when light passed through the air. And without reflection, we cannot see anything through light.
So we cannot see air as there is no reflection.
Can fish see the water?
No, they also cannot see the water for the same reason as us.
They also surrounded by water and light also have almost nil reflection when passing through water.
