Other universes may lie beyond the edge of our universe
We live in a vast and expanding universe with an observable limit of about 46 billion light years. This edge continues to expand away from us such that, rather than exposing more of the universe to us, we are actually seeing less of it. You can think of the edge of the observable universe as a kind of funnel. The bottom is in the past, about 13.77 billion years ago, only a few hundred thousand years after the Big Bang itself. This light rode the wave of expansion of the universe outward, wavelengths stretching redder and redder. Because of the stretching of space, the light was able to reach us in only 13.77 billion years despite being from 46 billion light years away.
As the observable universe expands away, however, the light from the most distant objects becomes redder and redder and those objects appear slower and slower, until, like an object falling into a black hole, those objects freeze and their light disappears.
Indeed, if the universe existed for an infinite amount of time, we would only be able to see a finite amount of it. This forever limits our ability to know exactly what size of universe we live in and whether it is actually infinite.
It also means that we cannot know what the “edge” of the universe is like. A better and more mathematical word for this is boundary. Some conjecture…
