Why do white holes appear?

Answer 1

White holes are hypothetical extension of eternal black holes. White holes, like black holes have properties like mass, charge, and angular momentum. Consequently a white hole will attract matter like any other mass. However any objects falling towards a white hole would never actually reach the white hole's event horizon, as it is the reverse of a black hole. In example, while a black hole can be entered from the outside, nothing, including light, has the ability to escape. Conversely while a white hole attracts matter, nothing, including light, has the ability to enter from the outside (e.g. matter and light have the ability to escape).

Note: The prevailing hypothesis is that there are no lone white holes. Rather a white hole, in general relativity, is a hypothetical region of SpaceTime which appear in the theory of eternal black holes. In addition to a black hole region in the future, such a solution of the Einstein field equations has a white hole region in its past. However, this region does not exist for black holes that have formed through gravitational collapse, nor are there any known physical processes through which a white hole could be formed.