Complementarity (physics)

Complementarity in physics is a big word that basically means two opposite things that can't both be seen at the same time. It's like trying to see inside a dark room with the door closed and open at the same time. You can only choose one way to see inside.

When we talk about complementarity in physics, we are usually talking about light or particles. There are different ways to study them, and scientists have found that when we try to observe them in one way, we can't observe them in a different way at the same time.

For example, let's say we are studying electrons. Electrons are tiny particles that make up parts of atoms. We can study them either as particles or as waves. When we study them as particles, we can see their position but we can't see their motion. When we study them as waves, we can see their motion but we can't see their position. We have to choose one way to study them at a time.

This is because of something called the Heisenberg Uncertainty Principle. It basically says that we can't know everything about a particle at the same time. It's like trying to catch a ball in the dark. We might be able to catch it, but we won't know where it is until we turn on the lights.

So, in summary, complementarity in physics means we have to choose how we study things like light and particles because we can't observe all of their properties at the same time. It's like trying to see inside a dark room with only one way to look in.