Before I go any further,
don't think about this too hard.
The universe... what is it? Well, it's everything. But what is "everything"? There obviously can't be an infinite number of objects in the universe. So, the universe must end somewhere. But where? Why would it end in that single spot? What if it doesn't end? How would that be possible?
What if the universe is a circle? Or a sphere? Or even a donut? What's outside of it? If the universe is everything, how could there be anything outside of it? But if the universe has a shape, how could there be no outside? What would the edge look like?
People say that the universe has an age. How can that be? What was there before the universe? Even outer space is something. But the universe can't have been around forever. Everything has an age.
And what about the big bang? If the universe was compressed into the size of a ball, a marble, or even an atom, what would be outside of it? Aliens playing marbles?
My head is hurting again, so I have to stop.