I don't believe it's infinite, with expansion theory almost universally accepted I think there must be an edge to the universe. What's on the other side is what interests me. Are there new laws of physics? New elements? Missing elements?
Is it a permeable membrane or an impenetrable shell? If one could ride the expansion wave (like surfing) they will be traveling faster than light speed, but what would happen in a place of no space/time?
I think my brain just went down the rabbit hole pondering that. And don't say white mice and 42. lol

@MacTavish Those theories are flawed - the Universe has always been here - and it extends forever.

@gater that's the beauty of theories, they are guesses. Perhaps educated guesses but still a guess. We have the option to believe which theory we want as it pertains to us.
I am curious though, how is the redshift observation explained in a non-expanding universe?

@MacTavish There is "the universe" which extends forever - this does not and can not expand. There is also the "Observable Universe" which is everything we can see. What we see is expanding.

@gater oh, ok, gotcha!!