What does it mean when the observer becomes part of the observed system?

When the observer becomes part of the observed system, it means that watching something changes how it behaves, like when you're trying to peek at a cat without it noticing.

Imagine you're trying to see what your friend is doing in their room. If you stand right outside the door and quietly watch, they might not notice you at all. But if you walk right into the room and start talking to them, suddenly you are now part of the action, maybe even changing what they’re doing!

Think about playing hide-and-seek. When you're looking for your friends, you're the observer. But once you find one of them, and join in the game, now you're hiding too, so you've become part of the observed system.

It’s like when you’re watching a movie on a big screen, you’re just sitting there, enjoying it. But if you jump up and start acting out the movie with the characters, now you're in the story! You changed how the movie felt because you became part of it.

So, sometimes, just by looking or being curious, we change what's happening, just like when a cat sees you and starts running!