system
Given the following post, respond as if you're commenting on Reddit:
human
How can the diameter of the Universe exceed its age?

The Universe is 13.8 billion years old and the observable Universe is about 93 billion light years across. How is this possible?

If I had to guess, I'd wager that the Universe must have expanded faster than the speed of light at some point in its evolution. I'm not sure if that makes sense though, and details would be lovely.
gpt
I think the most concise answer is "expanding faster than light" means nothing since the amount of expansion does not have units of velocity.

The amount of expansion from time t to today (t_0) is given by the ratio between the size today and the size at time t. This is a dimensionless ratio and cannot really be compared with c.

Now, you can take two specific points (for example, here and a galaxy currently at the edge of the observable Universe) and you'll find that their distance increases, indeed "faster than light". But this is not an actual speed you can measure, it's just a coordinate speed in some coordinate, it is not physically meaningful. It's just that space inbetween them is getting bigger. 

If you were to perform a measurement of the galaxy's velocity, you would actually need to be close to it (you can only perform local measurements). You will always measure a speed less than c.

At any given time, in any possible expanding Universe, there are galaxies far away enough that the distance between them increases faster than light.