Using the uncertainty principle involving time and energy, is it possible a universe and anti-matter universe be formed at the event horizon of a supermassive black-hole? If so, could one the anti-matter universe be consumed by the black hole leaving the matter universe?
I answered a question on anti-de Sitter (AdS) spacetimes and black holes here. An extremal black hole maps an interior region into $AdS_2\times \mathbb S^2$. The $AdS_2$ is not a universe in any way. However, in $10$ dimensions the extremal black hole generates $AdS_5\times \mathbb S^5$. The $AdS_5$ might be thought of as related to our universe or cosmology either as the equivalent conformal field theory $CFT_4$ on the boundary or as maybe the space of eternal inflation that spins off lower dimensional spacetimes in $4$ dimensions.
The extremal black hole is a case where it spins "at the speed of light," or has a null condition. This is not thought to exist. However a black hole might fluctuate off shell so its angular momentum uncertainty results in the extremal condition off shell. A black hole in $10$ dimension, or for that matter a black hole in ordinary spacetime with $6$ compactified dimensions might then fluctuate so the spacelike interior region becomes $AdS_5\times \mathbb S^5$. This might then be a quantum fluctuation that generates a cosmology or even the spacetime of eternal inflation.
This is admittedly fairly speculative. There are other speculative ideas as well. Smolin has proposed a way that black hole singularities might polarize the vacuum to induce quantum tunneling of nascent cosmologies.