We live in a colorful world.
It all begins with a never ending profusion of nuclear explosions in our sun. Eight minutes later all that radiation arrives at the earth in the form of electo-magnetic waves. Outside we are engulfed by white light. Thanks to Mr. Newton, who bent light with a prism—red, orange, yellow, green, blue, and violet—we understand that all colors are physically contained in white light. Inside the eye, a curious thing is happening.
So, what color is this tomato?
No, it's really not red, it's black.
If you were holding this tomato in the palm of your hand in a dark cave, it would be black.
Everything on earth is made of atoms which are full of invisible energy. If the energy contained in white light is compatible with the energy of an object, that energy is absorbed by the object. Energy that is not compatible is bounced off the object.
This tomato is absorbing, orange, yellow, green, blue, and violet energy.
The pupil then allows just the right amount of light into the eye to detect precise color. Rods and cones on the retina of the eye pick up the signal and decode the electromagnetic waves via the optic nerve in a mysterious spot at the back of the brain.
And voila, the tomato is red!