>>14332169>Why is it expandingWe do not have a complete cosmological model because we do not have a theory of Quantum gravity, Current Physics says expansion is an intrinsic characteristics of Spacetime.
>What is it expanding intoItself but with larger and larger distances among objects.
>If the universe is a closed systemThe universe being a closed system is not confirmed, however even if it is true, that wouldn't be a contradiction with the expansion. Imagine the surface of a Sphere with a Cartesian Plane on it, The sphere remain equal but the distances among objects on the plane will increase. At a certain point, for you, an external observer, it will seem like the objects stopped themselves. In reality they are still expanding infinitely toward the asymptotes of the plane.
