In astrophysics, a white hole is the time reversal of a black hole. While a black hole acts as an absorber for any matter that crosses the event horizon, a white hole acts as a source that ejects matter from its event horizon. The sign of the acceleration is invariant under time reversal, so both black and white holes attract matter. The only potential difference between them is in the behavior at the horizon.

Stephen Hawking has argued that white holes are the same as black holes, once quantum mechanics are taken into account.