Video narration
Is the universe expanding into something outside it? Look up at the night sky: you can see only so far. That limit isn't a wall around everything; it's the edge of the observable universe-the part whose light has had time to reach you. Beyond that view, there may be more universe; we simply can't see it yet. It marks the reach of our view, not a physical border around everything. That difference matters when you picture what expansion actually means. Here's the shift: the universe isn't an object moving outward through space. The distances within space itself are growing. On the largest scales, faraway galaxies grow farther apart over time; it's the space between them that stretches, not a flight into a surrounding void. We don't know whether the whole universe has an edge. No, expansion requires no room outside it at all.