White holes are seen in the maximally extended Schwarzschild solution, they are a region from the past that appear in the theory of eternal black holes, where the singularity exists in both infinite future and infinite past. Since time flows "looking" to the future, light rays can escape from the horizon into the universe and can never return. (ignoring the fact that it would take a infinite time)
However, I still have these questions about white holes:
- The wikipedia article says that objects falling towards a white hole would never actually reach it's event horizon, but in the case of a eternal black hole, the white hole event horizon becomes a black hole event horizon at the future, and that any objects would eventually reach it. So that means that white holes doesn't only happen on eternal black holes? Is it possible to have a white hole in the future or a "pure" white hole?
- How would anything escape the white hole, since it has positive mass and attracts matter? How can it's event horizon be a point of no entering?
- If time is reversed, wouldn't the gravity wave information travelling at the speed of light be reversed as well, making it repel matter?
- Is it absurd to say that a white hole would push matter into the past?
Thanks for reading, have a nice day.