ELI5: Explain Like I'm 5

Poincaré half-plane model

Imagine you are playing with a really big flat surface, like a tabletop or the floor. Now let's pretend that this surface is the entire universe, and on this surface there are a bunch of different shapes and points that we can explore. But, just like in real life, sometimes it's hard to move around on a flat surface. You might get stuck in corners or have to walk around obstacles.

This is where the Poincaré half-plane model comes in! Instead of thinking about the universe as a flat surface, we can imagine it as a big bowl-shaped surface. But, instead of focusing on the entire bowl, we only look at the bottom half of it. This is why it's called the "Poincaré half-plane model."

Now, when we explore the universe using this model, things become a lot easier. It's like we can walk around in a curved space instead of a flat one. Plus, all of the shapes and points we explore take on a different look when we see them in the curved space of the half-plane.

Overall, the Poincaré half-plane model is a really useful tool for exploring different mathematical ideas and concepts related to geometry and space. And, even though it might seem a little hard to understand at first, it's actually a pretty simple idea that can help us explore the universe in a whole new way!