The
question "what is outside the
universe?" is not an answerable question. The question itself is
absurd, since the universe
is space.
Everything that
exists, is part of the universe. There is no
outside the universe for anything to exist in.
This is similar to the question "what was there before the universe existed?". This question is equally absurd, since the universe is the combination of
space/time, therefore 'before the universe' there was no
time for anything to
exist in.