Explore the fascinating phenomenon of light's apparent slowing in different media while individual photons maintain their speed. Delve into Einstein's Special Theory of Relativity, Maxwell's equations, and the properties of spacetime that determine light's constant speed in a vacuum. Discover how charged particles in substances like water and glass interact with electromagnetic waves, creating induced light waves that interfere with the original. Understand the difference between phase velocity and group velocity, and how the latter explains the perceived slower speed of light in certain materials. Examine the quantum mechanical perspective, which describes the superposition of light paths and interactions with atoms. Gain insights into refraction, electromagnetic wave propagation, and the complex interplay between light and matter in this illuminating exploration of optical physics.