# On the death and rebirth of universe in a black hole

Suppose in the end there will remain only one very large black hole, others have died. Now this black hole had absorbed all the matter and energy of the universe due to conservation principle. Everything just cannot disappear. It has to be conserved somewhere. So this last black hole is a very massive thing.

And finally it must die too because the dark energy is pulling it apart. So it will not die like others. It is a special last black hole that is killed specially by the dark energy. It does not just evaporate. It is killed by dark energy (don't get too caught up on the killing idea, just make something up to make sense because this question is not really about it).

So when the last black hole dies it generates so much energy and bursts all the mass stored in its core that it starts another big bang. So another universe starts in the last black hole of this universe. But this new universe will never be able to escape out of the black hole because nothing escapes the event horizon.

Now i know this last part seems completely wrong. The last black hole already died so there is no event horizon left. But suppose through some mechanism the event horizon persists because this last black hole did not die like the other black holes simply evaporating. It was killed by dark energy, torn apart so maybe its event horizon still remains intact.

Then that means one universe is formed in another and we can never really communicate with the other universes.

Is this at all possible?

• The universe isn't going to end up as a single massive black hole so your question isn't really answerable. Jun 6 '19 at 6:25
• @JohnRennie Is that true? I thought a consequence of accelerating expansion was that eventually galaxies outside of the Local Group would be redshifted to undetectability, so that observers in the very far future might become unable to reconstruct the history that we've worked out. (I am not confident that I can find the article where I read this.) And since we have now observed that gravitational orbits are, eventually, unstable against gravitational radiation, having only black holes remaining is a plausible long-term state. The time scales are really, really long, though.
– rob
Jun 6 '19 at 12:51

Dark energy doesn't pull apart black holes unless we have $$w<-1$$ and get a Big Rip scenario. If you have an empty universe with dark energy and a black hole there is the de Sitter-Schwarzschild class of solutions to general relativity that describe it, and this is a static situation.