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I know that difference between different colors of light is difference between their wave length but I don't know what gives beautiful colors (like rainbow colors) to different wave length of observable light?

What makes our eyes to see different wavelengths of light as different colors?

Remark: I've meet someone which he was color blind, he was not able to see rainbow colors. So the process that gives color to light must be in our eyes and brain.


marked as duplicate by MCM, blep, MattDMo, Daniel Standage, Rory M Apr 19 '13 at 21:43

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  • $\begingroup$ This is not a physics question, but a biology question. Please ask on biology.se instead. $\endgroup$ – Kenshin Apr 18 '13 at 0:47
  • $\begingroup$ Basically cone-cells in the eye detect colours and consequently send an impulse to the brain. $\endgroup$ – Kenshin Apr 18 '13 at 0:58
  • $\begingroup$ Our eyes detect light waves of different wavelengths, which we then perceive using our brain as colour. $\endgroup$ – Kenshin Apr 18 '13 at 1:10
  • $\begingroup$ @Chris: This really falls in the gap between physics and biology; I don't see it as belonging clearly to either. Is there a bio-physics.se yet? $\endgroup$ – Pieter Geerkens Apr 18 '13 at 1:30
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    $\begingroup$ @Anixx: You have been told before: Philosophy-like tags like 'metaphysics' tag are not allowed, cf. e.g. this and this meta Phys.SE post. $\endgroup$ – Qmechanic Apr 18 '13 at 9:15

Three different types of cones in the eye are sensitive to three different, contiguous and slightly overlapping, sections of the visible spectrum. The nerve signals from these three different types of cones are interpreted by different sections of the brain as cyan, magenta, and yellow, from which all the discernible colours are composed. This forms the familiar Colour Triangle.

The sides of the Colour Triangle bulge slightly (I believe) because of the slight overlap in the sensitivity ranges of the three cone types.

Colour blindness occurs when someone is born with only two (or rarely one or none) different types of cones, instead of the usual three. This causes an inability to detect one of the thee sub-spectra.

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    $\begingroup$ you should add a sentence that addresses the double value :both the frequency spectrum is seen correctly and the mixture of three frequencies can give the same color response even though the "clean" frequency is missing. $\endgroup$ – anna v Apr 18 '13 at 4:11

This is a philosophical question rather than physical. I believe it is off-topic here.

I suggest you to look up for for qualia.



  • $\begingroup$ i dont think this is about qualia.. anyways the question should be clearer.. but since you reminded me about qualia, i remember that i always used to wonder if someone else/ some other organism "sees" green exactly the way I see. in fact qualia do have physiological explanations. Using fMRI, perhaps, one can find if two individuals perceive a colour similarly. :) $\endgroup$ – WYSIWYG Apr 19 '13 at 11:43
  • $\begingroup$ This should be expanded or it's more of a comment $\endgroup$ – Rory M Apr 19 '13 at 15:52
  • $\begingroup$ The problem of knowledge has always been debated among philosophers and physicists. Many problems are on the border between two sciences. It is a non-sense to say which is the right approach. They are just two different points of view. So, we can speak of cones receptive to understand through which neuro stimulations colors can be perceived. But we are not able to say as the colors are psychologically and subjectively interpreted. Two different points of view, the first scientific and the second absolutely subjective. Both have their own sense of logic and heuristic. $\endgroup$ – violadaprile Apr 20 '13 at 12:22