ELI5: Explain Like I'm 5

Hurwitz's theorem (normed division algebras)

Okay kiddo, let me try to explain Hurwitz's Theorem to you in a way that you can understand.

First, let's talk about numbers. You know what numbers are right? Like 1, 2, 3, 4...?

Well, in math, there are different kinds of numbers that have different properties. For example, some numbers can be multiplied by other numbers to get a result that is also a number.

Now, when you multiply two numbers together, you get what's called a product. For example, if you multiply 2 and 3, you get 6.

But not all products are the same. Some products have special properties that make them more interesting.

That's where Hurwitz's Theorem comes in. It's a special rule that tells us something about the products of different kinds of numbers.

Specifically, it tells us that there are only a certain number of kinds of numbers that have special properties when you multiply them together.

These special numbers are called normed division algebras. They have special properties like being able to multiply any two numbers together and always getting another number that is also a normed division algebra.

But here's the thing: there are only four types of normed division algebras. That's it.

So Hurwitz's Theorem is just a fancy way of saying that there are only a certain number of special number types out there that have really cool multiplication properties.

Does that make sense?