Wormhole, illustration. Black hole (top) connecting to a white hole (bottom) via a wormhole. A white hole is a hypothetical object that is the mathematical opposite of a black hole. Matter is drawn into a black hole and would be ejected from a white hole, possibly passing through a wormhole in the process. Wormholes are theoretical portals through spacetime, existing not just in space, but in the further dimension of time as well. The concept of curved spacetime, and using wormholes to travel to distant parts of the universe, are derived from Einstein's General Theory of Relativity.