EMPTY SPACE OUTSIDE THE UNIVERSE

The Big Bang was the moment when the expansion of space happened everywhere. The Universe isn't expanding into empty space, because the universe does not require space to exist outside it. The universe is everything, so there is no "outside" the universe. The universe is infinite in every direction. This means that no matter for how long you travel in a straight line, you will never reach the place from where you can "exit" the universe and see what's outside. The universe is not a bubble that expands into nothingness. The visualizations that show the universe is a bubble that expands into nothingness are sometimes misleading, because you create a perception that the universe is inside empty space, and it's expanding inside of this empty space.