I've asked myself the same question often enough and never found an answer. I can't give you one
either, for it puzzles me as much as you why scientists come up with such obviously incongruent
notions, which leave the word 'universe' out on a limb as a meaningless concept. Alternatively, of
course, you could look upon it as an embarrassment of our understanding: we want to know if the
universe is all there 'is', but we can't know, and so we look at atoms and electrons and quarks and
leptons and imagine that in their rhythm a mirror image of the rhythm of the universe is displayed.
Sorry: this is no answer. But there isno answer, and therefore the whole question is null and void.
Perhaps that's one good reason why we still need philosophy!?