Question: What do you think is outside the Universe?
I think there might be other Universe in my opinion. What do you think is outside the universe?
Why yes there are most likely more universes.
Like how there is not just one star, there are actually many stars within one galaxy.
But you can't just stop there, there are also many galaxies within galaxy clusters.
Oh, but there are also many galaxy clusters within one universe.
In this logic, there is not just one universe.
What you say is being said by many. They call it a multiverse.
A galaxy contains millions of stars and the stars revolve around the centre. Maybe there are many "universes" containing millions of galaxies each and these "universes" maybe revolving around something we can't even try to imagine of..
The inside of this universe.
What is inside your ovaries?
(I am assuming you are male and do not have ovaries.)
My point is that placing words into a sequence to form a sentence (or question) does not mean that the question means anything.
The universe by general consensus is "all there is". It should be obvious, even to someone with limited intelligence, that there can be nothing else. So, the only way for your question to have meaning is to change the definition of the word "Universe" into something like "Our connected 4 dimensional space-time manifold".
There is a serious problem with that solution. (Remember, the problem is that your question as commonly understood is nonsense.) Science is the study of those things which are capable of having an observable effect. Science doesn't study those things which do not have any testable outcomes. That would be religion or philosophy or the supernatural, not science. (This is one of the major objections to string (m-brane) theories.) For there to be scientific observations or theories about something "outside" of "our connected 4 dimensional space-time manifold", it would have to somehow BE connected (to have an effect). This is in direct contradiction to the assumption that if it is connected then it is part of our Universe. Hence you can believe that there are Green Easter Bunnies and Orange Great Pumpkins, Hobbits and vampires, or anything else you want "outside" our universe. It is all the same since it can not, by definition, ever be proven or disproven.
IOW, forming sentences (and thoughts) to express ideas about things "outside" of Universe is as futile as discussing the contents of your ovaries. It means nothing. (Of course, we do know that testicles and ovaries develop from the "same" embryonic cells, because we have been able to study our ontogeny. It is a fundamental requirement of Science that its subject is restricted to the real.)