For 20 years or so I gave a certain lecture introducing the fundamentals of virtual reality. I'd review the basics of vision and hearing, as well as of touch and taste. At the end, questions began, and the first was often about smell: Will we have smells in virtual reality machines anytime soon?
Maybe, but probably just a few. Odors are fundamentally different from images or sounds. These latter can be broken down into primary components that are relatively straightforward for computers to process. Every sound wave is actually composed of numerous sine waves, each of which can be easily described mathematically. Visible colors are merely words for different wavelengths of light.