Kalam cosmological argument (part 1)
Universe is all existing matter, energy and space, so it's a super-set of all "whatever"'s. A super-set does not necessarily contain the same properties as the objects of this set. For example, every person in a crowd has a mother but the crowd itself doesn't have a mother.
Universe indeed began to exist and the moment of existence is called the Big Bang. But it cannot be said that it has a "cause", at least not in the same context.