Color does not exist out in the world anywhere other than within your own nervous system. What we experience as color is a perceptual process formed in our nervous, not a universal quality or characteristic of the physical world. Our nervous system evolved specialized sensory cells which allow our brain to perceive the phenomenon of color because of the usefulness to us of the information that can be carried in the selective absorption and reflection of a narrow band of electromagnetic energy. Essentially, our brain has learned to “do something” with that form of energy just as it’s learned to do something with a handful of other physical forces (so-called “sound waves”, molecules wafting into our sinuses, various pressures, chemicals, and temperature gradients). Likewise, we have NOT evolved to directly make use of all kinds of other physical forces in nature. For example, we cannot perceive most of the electromagnetic spectrum that “light” is but a small portion of, such as x-rays, infrared, gamma rays, microwaves, etc.). We are bombarded by all of these and others just as much, if not more, than light waves, yet we cannot perceive them. What does magnetic force look, smell, or taste like? The obvious answer, none of these “perceptions,” or any other to humans. But those forces are doubtlessly around us and real. Just as NOT perceiving them doesn’t make them unreal out there, so too does perceiving certain qualities of light make colors real out there.