ELI5: Explain Like I'm 5

Classifying space

Imagine you have a bunch of different types of toys, like cars, dolls, and blocks. You want to put them into groups so it's easier to find the one you want to play with. So you decide to make three groups: cars, dolls, and blocks. You've just classified your toys!

Now, let's talk about space. Space is really big and can be hard to understand, but scientists have found a way to group certain types of spaces together to make it easier to study them. They call this "classifying space."

One way they classify space is by its shape. Just like you can group toys by type (cars, dolls, blocks), scientists can group different types of space by their shape. One type of space is called "Euclidean space." This is the kind of space that you're used to thinking about - it has a flat surface and straight lines. Another type of space is called "spherical space." This is a type of space that curves like a ball.

Scientists also can classify space by how many dimensions it has. This might be a little harder to understand, but here we go! You're used to working with things that have three dimensions - length, width, and height. But scientists can imagine spaces with more dimensions than that. For example, a 4-dimensional space would have length, width, height, and something called "time." This might sound really weird, but it's actually really helpful for scientists to imagine these higher-dimensional spaces when they study things like the universe.

So, to sum it up: scientists classify space by grouping together spaces that have similar shapes (like how you group toys by type) or by grouping together spaces that have similar numbers of dimensions. This helps scientists understand space better and make predictions about how things in space will behave.