in nature, a rainbow has no stripes—it’s a continuous spectrum of light, with wavelengths that range from approximately 400 to 750 nanometers. This spectrum has no borders or bands of any kind. Why do you and I see stripes? Because we have mental concepts for colors like “Red,” “Orange,” and “Yellow.” Your brain automatically uses these concepts to group together the wavelengths in certain ranges of the spectrum, categorizing them as the same color. Your brain downplays the variations within each color category and magnifies the differences between the categories, causing you to perceive bands
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