What is beyond space?

Space is understood as being four-dimensional — finite, but without borders or an edge. Here’s a three-dimensional example: One can travel on the surface of Earth as long as one wants, never finding a boundary or edge, and yet Earth is finite. Some astronomers think that our universe is not alone, that there may be zillions of other universes that began with a big bang, will last for billions of years, and then will disappear.