ELI5: Explain Like I'm 5

Bousso's holographic bound

Imagine you have a big toy box filled with all your toys. The toy box is like the universe, and the toys are everything in it – like stars, planets, and galaxies. Now, imagine a sticker on the outside of the toy box that says "maximum capacity: 100 toys". This means you can only have up to 100 toys in the box before you have to take some out.

In real life, scientists have discovered something similar to this sticker in the universe. It's called Bousso's holographic bound. It says that the amount of information (like how many toys) that can be stored in a certain amount of space (like the toy box) has a limit. That limit is based on how much gravity is in that space (like how heavy your toys are).

Basically, the universe has a maximum amount of information it can hold, just like your toy box has a maximum amount of toys it can hold. This holographic bound helps scientists understand how much can fit in different parts of the universe, and how gravity affects that. It's an important tool for understanding the big picture of the cosmos.