Instead of molecules that absorb light based on their molecular orbitals, this episode talks of nanostructures and their materials that refract light based on interference of light waves. We start with Robert Hooke who described this process in his book Micrographia. We continue through Isaac Newton and Lord Rayleigh. We discuss Eli Yablonovitch's photonic crystals. We mention various kinds of natural structural colorants in the living and non-living worlds, from minerals to insects to bacter...