How well supported are the theories of black-holes containing their own universes? The thought crossed kidnapped my mind one night almost a year ago. I was laying down, but I was very interested in thinking about the secrets of a black-hole.

Nat. Geo. - News article

What does the current state of research tell us about the idea that black holes might form universes?

Don't forget to backup your answer!
More and more of modern theoretical physics deals with unphysical models and ideas. The only basis we have of predicting what is happening beyond an event horizon, ANY event horizon, is what we understand about what happens around us, on this side of that horizon. Feel perfectly safe in making up anything you wish about what the Physics is like beyond the event horizon, we'll never be able to contradict you. We'll never be able to falsify any claim made for events on the other side.

Purple people eaters? Why not? Ghosts and Gods? Sure. 1+1 = 3? Yup, that too. The event horizons in nature are the natural limits to our Universe. The edge, if you will. Unless and until we are able to observe consequences of the claims you make (called verifiable predictions) you're not dealing with Science, at least not what I regard as Science.

Right now, we know of 4 types of edges to our Universe:


The edge at ~1E-44 seconds after the hypothetical Creation Event
The event horizon of any black hole
the event horizon at about 15-20 billion light-years distance (at which space is expanding at greater than the speed of light and
the edge of our Observable Universe (from which no signals will ever reach us).


Physics is about what goes on on this side of these "edges". Metaphysics, philosophy, religion, opinion are what you may use to deal with those things beyond, but don't call it physics or science.

P.S. I am sympathetic to the idea that there may be an (as yet unknown) physical law which prevents singularities from actually forming. In fact, we have only weak indirect evidence that event horizons actually exist, and absolutely none that singularities form. Generally, when a physical theory and its mathematical expression leads to infinities, we change the theory - see renormalization.

You want to know about multiverses or what is beyond the event horizons of black holes? OK. I want to know about the color of the nail polish that the tortoise carrying the Universe on its back uses. Both are equally valid areas of inquiry. See for example https://en.wikipedia.org/wiki/Multiverse#Proponents_and_skeptics ... and links found there.

I should also mention that you know an article which talks about events prior to time zero (which I call the Creation Event) are metaphysics and/or religious. None of them, I repeat: none of them are based on known Physics. (Why? because our known physics breaks down at about 10E-44 seconds, extrapolating back to t=0 isn't possible.) Sure they make an interesting story, but they should be regarded in the same way as any fiction. You get to choose which you like and which you don't without any regard for ever having to justify your choices.

Much of human knowledge is about narratives which allow us to understand our place in the Universe. It is part of our human nature to be curious and seek out narratives that make sense of our world. The set of scientific narratives differ from this set because the goal is different. They doesn't require our understanding (for instance, Feynman said: "I think I can safely say that nobody understands quantum mechanics." (1965) Little has changed since then.), they only require our ability to apply them to make/verify observations.

Creating a satisfying narrative does not require the scientific method(s) be enforced. But ignore them at your peril.