Dr. Sapiro attempts to shed some light on how light waves can be aligned to interfere with each other to form a standing wave with a crystal lattice structure. This structure, called an "optical lattice," is a powerful tool that can be used for a wide variety of applications: it can force large microscopic and/or biological particles to form crystals; it can induce unique states of quantum matter; and it can be used to explore fundamental principles of quantum mechanics. An optical lattice can also be used such that the role of light and matter is reversed, with the matter behaving like a wave reflecting and diffracting off the crystal-like light.