The nature of reality must be more complex than possible for us to even imagine. We exist within the universe, as far as we understand it, which means we are made of whatever the internal universe is made of. We have no means of accessing, perceiving or even understanding the origins of the outer universe.
Like a character in a story, it is not possible to question what exists beyond the page without the question itself being posed within the universe using the rules of the universe.
Knowledge of the outside must be discovered with tools from the outside. We have no means or reaching these tools.