Question

Why we can't see gamma rays ?

Answer 1

The mechanics of color vision are pretty simple. The typical human retina has four types of receptor cells: rod cells, short wave cones, medium wave cones, and long wave cones. The rod cells respond to light with wavelengths about 375 nm - ~700 nm, but the lens of the eye blocks out most light below 400 nm, so you are really limited to seeing 400–700 nm. As you get into x-rays around 10 nm or so, the light has enough energy to penetrate through the lens, but then it is also likely to penetrate through the retina as well. Since the light has too much energy to be absorbed by the sensor cells, we cannot sense that light. Since gamma rays have even more energy, they are even more difficult for the human eye to detect; however, some people have reported seeing flashes of light when exposed to high concentrations of gamma radiation. The best guess is that the gamma rays can interact with the fluid inside of the eye, causing a sort of fluorescence within the eye. This is extremely dangerous, though, as gamma radiation is ionizing radiation capable of penetrating deep into the body damaging vital tissues in its wake.

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