I have recently become interested in the theory of color and light production and interaction with matter, particularly in organic and other natural settings. This page and its supplements give a brief overview of how light is produced, scattered, and reflected to create the many colors that we see in the natural world.
The interplay of light and matter has been studied for centuries, culminating in the electromagnetic theory for light and Maxwell's equations at the end of the 19th century. Other topics such as scattering, iridescence, fluorescence and adsorption/emission were added to the theory shortly thereafter with the development of quantum mechanics. It was only then that seemingly innocuous questions like "Why is the sky blue?", "What makes carrots orange?", and "How does a firefly glow?" could be answered within the framework of physics and chemistry. It has been proposed that all of the colors we see in nature stem from only fifteen physical causes, and here we examine only a few of them: conjugation of organic molecules, bioluminescence, fluorescence, interference, and molecular vibration.