White hole

A white hole is a hypothetical region in spacetime. It has not been proven to exist. It is predicted by the general relativity as a place before an ideal black hole.

It is said to be the exact opposite of a black hole. While a black hole sucks in objects to its singularity, the white hole emits matter from its singularity. A white hole may be formed after a black hole can no longer suck things in. Immediately, it turns into a white hole and starts emitting the things that it has previously sucked in before. Nothing can enter a white hole as its emitting force is too great. In this sense, it is the reverse of a black hole, which can be entered only from the outside and from which energy-matter, light and information cannot escape.

An artistic view of a white hole.

Like black holes, white holes have properties like mass, charge, and angular momentum. They attract matter like any other mass, but objects falling towards a white hole would never actually reach the white hole's event horizon in any reference frame, unlike how a black hole will let things cross its event horizon in their reference frame. If white holes emit what black holes absorb, then they would not need to be actually white, and would be the color of whatever came into the black hole, although they may still be very bright.