ELI5: Explain Like I'm 5

Irreducible representations

Imagine you have a group of toys, like your favorite stuffed animals, and you want to know how they can be moved around and still look the same. This is what mathematicians call a "group". Just like you can move your toys around and still recognize them, there are certain rules that determine how you can move the members of a group around and still have the group look the same.

Now, imagine these toys have special powers, or "symmetries". Some toys can be flipped over without looking any different, while others can be rotated around without changing their appearance. Just like each toy has its own powers (symmetries), mathematicians have ways to understand and categorize the different symmetries of a group.

An "irreducible representation" is one way to describe the symmetries of a group using math. This means finding a set of "matrices" (think of them like boxes) that can tell you how each toy can be moved around and still look the same. "Irreducible" means you can't break these matrices down into smaller pieces - they are like building blocks that can't be taken apart any further.

So, if you have a set of irreducible representations for a group of toys, you have a way to understand all the different symmetries they have, and how they can be moved around and still look the same. It's like having a set of rules and tools to help you understand the special powers of your stuffed animals, so you can play with them in even more ways!