Once a black hole has formed will it ever go away or will it just keep getting larger?

Question

Since no one knows the properties of a singularity, could there be a black & white hole on the other side emptying into another universe and it just so happens that our universe is on the side with all the black holes?

Answer 1

A Black Hole gives off “Hawking Radiation”. The amount depends on the size of the Black Hole. Large Black Holes take an immensely long time to lose all of its mass to radiation and disappear. Smaller ones lose mass so quickly it appears to be an explosion.

It is accepted that when a proton decays, it forms a Black Hole smaller than a subatomic particle. Its evaporation is nearly instantaneous.

A Black Hole doesn’t have any sides and is not a doorway. It has a mass of a star (or many stars) and an object can orbit it just as a planet orbits the sun. An object entering a Black Hole does not go “through” it to any other place. If it did, the mass would diminish. All of its mass stays in the singularity except for the Hawking Radiation.

Answer 2

will get larger

Answer 3

It depends on how big it is.  If the BH is the mass of a few stars or more, then it will grow as more stuff falls into it.  But after several billion years, just about everything that is going to fall into it will have done so.  Then Hawking Radiation takes over, and the BH slowly evaporates.

And actually, lots of people know about the properties of a "singularity".  There are still a lot of details to work out, because the center of a BH combines super-gravity with quantum physics, and we don't have a good set of equations for that situation yet.  But we know the limits of what it is like, and no, there is no "white hole" on the "other side".

Answer 4

If a black hole could exist,eventually it would accrete all the matter in the universe and sit for eternity doing nothing.

  Though a black hole is an elegant theoretical entity there are some very good reasons why it can't exist.