The concept of an “edge” of the universe is not applicable under the framework of current cosmological models. The universe is often described as having no center or edge in the conventional sense. It is more practical to think about the universe as being similar to the surface of a balloon. When the balloon inflates, every point moves away from every other point, but there is no “edge” on the surface itself. So, it’s not expanding into anything; rather, space is expanding and carrying galaxies with it.
As for where the universe expands to, it’s crucial to note that the expansion of the universe is the expansion of space itself. There’s no space “outside” the universe into which it is expanding. This can be a challenging concept to grasp because it’s quite different from our usual experiences and perceptions confined to three-dimensional spaces.
Regarding what existed before the Big Bang, our current understanding is limited because the laws of physics as we know them break down at the singularity from which the Big Bang is thought to have originated. Theories such as quantum gravity are working toward providing answers, but as of now, it’s more accurate to say we don’t know. There may not be a “before” in the traditional sense because time itself is thought to have begun with the Big Bang, meaning the question may not apply in a pre-Big Bang context. This remains one of the profound mysteries in cosmology and physics.
