system
Given the following post, respond as if you're commenting on Reddit:
human
The known Universe is over 72 billion light years across. How is this possible if the big bang was only 14 billion years ago?

Is it possible that we are seeing remnants of a universe older than ours? Is it another universe co-existing with ours, meaning that this is a multi-verse? Or is it from another big bang that has happened extremely far away from us, creating another universe, meaning that this is a multi-verse?
gpt
It's because of the expansion of space itself. It's quite difficult to explain because it isn't like any traditional form of motion you're used to. When space expands, the objects themselves don't need to be moving, but the relative distance between them increases.  

As an analogy, imagine we are two dimensional beings stationary and equally seperated around the rubber membrane of a balloon. When the balloon is inflated (representing the metric expansion of space), our two-dimensional selves get further apart from each-other. But we didn't actually move at all, it's just the fabric of our universe (in this case the rubber) was stretched.

This is by no means a perfect analogy but hopefully it helps.