Is the inside of the eye ball empty space? Or it is filled with oxygen?
It's filled with goo called vitreous humour (just a 16Century way of saying goo)
It is filled with a clear jelly/liquid called the vitreous humor:
Dagna-bit! mgb is too quick AGAIN!
The eye has two distinct fluid-filled compartments. The aqeuous humor exists between the cornea and lens, while the vitreous humor is between the lens and retina. They are not static bodies of fluid; each is produced, flow, and is resorbed.
Interestingly, the goo has an index of refraction that is different than that of air. Which means that the speed of light is different there. Which means that the wavelength of light is also different in there than it is in air. This means that what we perceive as green light wouldn't necessarily be green, or the same tint of green, if the goo was drained from the eyeball or replaced with another type of goo or matter.
In essence: The wavelength that is perceived by our retina is different than the wavelength that is traveling from the light source to our eye.
That's a common misconception- although the wavelength (momentum) does change, the frequency (energy) does not. The color detected is based on energy, and hence is unchanged.
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