|MadSci Network: Other|
Your question is beyond the scope of science. Science assumes that what we perceive -- including what we detect with instruments -- is real; your question is a good one but denies that assumption. For example, a scientist would say that color is really there, but color-blind people are not equipped to detect it. Normal people have the same problem with ultraviolet light, which insects can see; and all living things have this problem with gamma rays, which detectors can "see."
You'd do better to ask a philosopher, though there is considerable disagreement! I recommend Mortimer Adler's book Ten Philosophical Mistakes for a nice treatment of your question.
P.S. Incidentally, some scientists and philosophers of science do make a distinction between "color," which is what we perceive, and the wavelength of the light which causes the "color" response. In my opinion, and that of Adler, this is a distinction without much difference as two people (assuming one of them is not color-blind) can agree upon the color of a particular wavelength of visible light; for that matter, a bee and a flower can "agree" on the color of a particular wavelength of ultraviolet light. For me and for Adler, this means that "color" is something objective.
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