ELI5: Explain Like I'm 5

Category of metric spaces

Okay, let me try to explain this in a way that a 5-year-old could understand.

So, you know what a map is, right? It's like a picture of the world that helps us find places and get from one place to another. Now, imagine that you have different maps of the world, but each one shows different things. One map might show all the mountains, another might show all the rivers, and another might show all the cities.

In math, we have something called a category, which is like a box of maps. But instead of showing places on the world, these maps show different kinds of math structures. One of these kinds of math structures is called a metric space.

A metric space is like a map that shows how far apart things are from each other. Just like on a map, where you can measure the distance between two cities with a ruler, in a metric space, you can measure the distance between two points with a special rule called a metric.

So, the category of metric spaces is like a box of maps that all show different ways of measuring distances. Some of these maps might show how to measure distance in a flat, two-dimensional plane, while others might show how to measure distance on a curved surface, like a sphere or a donut.

By putting all these maps in one box, mathematicians can study the different ways to measure distance and how they relate to each other. Just like how looking at different maps of the world can help us understand how different places are connected, studying different kinds of metric spaces can help us understand how different math structures are related to each other.