How is that possible? Is it because the electrons are interacting with more particles which somehow allows them to move faster?

Nuclear reactors and their radioac' tive fuel rods are often submerged in pools of water that absorb their radiation. These pools glow with the gorgeous cerulean blue light you see in the photo. This glow, an example of a phenomenon called Cerenkov radiation, is caused by energetic electrons that travel faster than the speed of light in water. Nothing can travel faster than the speed of light in vacuum, but there's no law against exceeding the speed of light in a given medium. The fast electrons, which originate in nuclear reactions, interact with atoms in the water, which emit light. Because of the electrons' speed, these interactions are conv ned to a shock wave like that of a supersonic jet, and the emitted light is mainly blue