Cherenkov effect

The Cherenkov effect occurs when a charged particle, like an electron, moves through a medium such as water or glass faster than light travels within that medium. While nothing can exceed the universal speed of light in a vacuum, light slows down in other materials. When a particle surpasses this reduced speed, it emits a faint, bluish glow known as Cherenkov radiation. This effect is similar to a sonic boom but with light, and it is often observed in nuclear reactors or scientific detectors to identify high-energy particles.