Every day I wake up and use the mirror to get ready for work or school. I can’t tie my turban without a mirror. I can’t put my contact lenses in without a mirror. Still, I have no idea how this simple yet essential tool works.
In high school science classes, I learned about the angle of incidence and the angle of reflection. The Law of Reflection stated that for light, the angle of incidence (the angle at which light enters a surface) is the same as the angle of reflection (the angle at which light leaves a surface). However, this would propose that light stopped when it hit the mirror, changed directions, then accelerated back to light speed. This would violate laws of physics as photons are not allowed to stop or slow down.
The physics behind this reflection is a little tricky, but really it can be boiled down to a game of hot-potato. Mirrors are just panes of glass coated with metal, usually silver. This metal coating has an outer layer of electrons that just wander around looking for things to do. When light encounters the mirror coating, these electrons snatch away the photons and absorb them in the molecule. But this is too much energy for the molecule to handle, so it releases this energy by emitting more photons away, creating the “reflection” of light.
Why can only mirrors reflect light properly then? It all has to do with molecular structures and the physics of light. When the surface is smooth and has free electrons that need something to do, it acts like a mirror. When the surface is rough and the electrons are busy doing something else, it just diffuses the light rays. Consider this, water in a pool or a glass acts as mirror, but when it turns into ice or snow, the texture change causes the reflection properties of water to disappear. Water is a magical thing, and so is science.