Colours Don't Exist

        They're all in your head.

        Cells in your retina are sensitive to different wavelengths of light. Some more or less so in others. No one sees things in quite the same way, though close enough that someone direct another to a "red door" and others will understand, except in the case of colorblindness. Even then, people with this condition can figure out what objects are "red" by way of inference and contextual clues.

        These wavelengths are interpreted as different colors by your brain.

        Objects absorb and reflect these wavelengths of light that hit them. When we say an apple is red or an orange is orange, we are talking about the interpretation of absorbed wavelengths of light in the object. These wavelengths of light correspond to different colours which are measured in nanometers (nm). For example: yellow is approximately 600 nm and violet 400.

        Similar to the way in which humans perceive a limited range of sound frequencies we also perceive a limited range of wavelengths of light. Other animals perceive a broader spectrum.

        So, whoop dee whoo!