i’ll never forget when i was in science class in high school- and the teacher told the class that space never ends and has no beginning— a girl stood up and said that there has to be an end or a wall or something.. i told the girl- well, whats on the other side of the wall? confusion set in quick..the bible states that God had no beginning and has no end— the human mind cant understand a no beginning and no end— stange huh?— just thought i would share that—ha ha
There is a cosmological answer to that question. You’ve seen the model of space as a grid in which physical objects make indentations?
The gravity of those objects actually bends space. More properly it could be called space-time, because space and time are essentially two facets of the same thing.
The universe does this as well. So if you made a perfectly straight line heading to the “side” of the universe, after a very, very long trip, you would end up at the same point you started from, offset by other internal movement within the universe.