universe - Why would it matter to us if space is infinite versus being finite?

More specificlly, what are some of the differences for contemporary sciences and humanity if there are multiple universes versus just one?

I ask because I'm writing a story and I want to put into perspective some of the implications such a difference would make on the sciences and on humanity. How would such a paradigm shift change the way reality is perceived? What would some of the implications be for the average person?

For example, obviously the way the big bang is interpreted would be vastly different. For example, if there are multiple universes, then maybe the background radiation so often cited as primary evidence for the big bang would be reinterpreted or, for example, maybe the big bang wouldn't be perceived as the starting point of "everything" anymore but just a gigantic explosion of sorts that has to happen every so often in certain pockets of space-time.

Maybe it would also change other theories of gravity that are otherwise thought to be very well understood, for example. Maybe it would change our understanding of time, I don't know. Like I said, I'm writing a story wherein I'd like to be able to put into perspective some of the "real-world" effects any such "series of discoveries" would have if they led to the strengthening of a multiverse hypothesis, such that it became an accepted theory. I'm going to need for my reader to appreciate why we would want to know such, aside from merely knowing it.

Thank you.