This is discussed on reddit science
It's the latest in a series of papers exploring the idea that black holes and the big bang/inflation are actually the same phenomenon, just looked at from opposite sides of an event horizon.
The implication would be that the universe we know is simply a bubble holding matter pinched off from a larger universe and similarly black holes in our universe are exploding into universes of their own as they form.
It's very appealing asthetically, but these speculative theories don't have a great track record of holding up once they finally make testable predictions that can be measured.
If spacetime torsion couples to the intrinsic spin of matter according to the Einstein-Cartan-Sciama-Kibble theory of gravity, then the resulting gravitational repulsion at supranuclear densities prevents the formation of singularities in black holes. Consequently, the interior of every black hole becomes a new universe that expands from a nonsingular bounce. We consider gravitational collapse of fermionic spin-fluid matter with the stiff equation of state in a stellar black hole. Such a collapse increases the mass of the matter, which occurs through the Parker-Zel’dovich-Starobinskii quantum particle production in strong, anisotropic gravitational fields. The subsequent pair annihilation changes the stiff matter into an ultrarelativistic fluid. For a typical stellar black hole, Mb is about 10^32 solar masses, which is 10^6 larger than the mass of our Universe. As the relativistic black-hole universe expands, its mass decreases until the universe becomes dominated by nonrelativistic heavy particles.
A reddit science comment that tries to explain the paper in simpler terms
It seems to me, he's suggesting that when a black hole forms, another entire universe is created inside the black hole, and his math claims to support the energy levels and physical mechanisms necessary for this to happen, complete with an explosion/expansion phenomenon inside the black hole that more or less matches the big bang and subsequent inflation we theorize as the beginning of our own universe. The collapse toward a singularity is a catalyst which triggers a chain of physical events that generates more energy/mass than we see in our own universe.
All of this brand new conservation-violating mass that is spontaneously created inside this new universe is generated by quantum particle production which only occurs in near-singularity conditions. We already accept particle-antiparticle pairs popping in and out of existence in empty space. The gravitational conditions at near-singularity break the balance and stop the particle annihilation, leading to the production of an entire universe of matter almost instantaneously, which causes a big bang and subsequent inflation.
It also prevents a true singularity from ever forming - there is no divide-by-zero error in this model, though what has replaced it could be described as multiply-by-infinity. The mass of the new universe is influenced by the mass of the matter that vanished into the event horizon. For a typical stellar black hole, the mass of the new universe is 106 greater than our own universe according to his incomprehensible calculus.
So, if you threaten mother nature with the possibility of a singularity, she responds with a universe-sized explosion. Please do not share this information with the Pentagon.
We do not see the big bang because, from our perspective, thanks to time dilation, it literally never happens since infinite time must pass. The formation of the event horizon - the black hole itself - is the first instant of such a big bang, on this end, frozen in time by gravitational time distortion.
In other words, the only reason the black holes we observe haven't blown up and killed all of us is because time itself has prevented them from doing so, thanks to the obscene gravity levels present.
Where this other universe exists is anyone's guess, since the concept of 'inside' a black hole doesn't really have any meaning. Where is 'on the other side of the event horizon' which is a place you can never go. You have to be inside the event horizon when it forms to get there. Once it forms, you are locked out, or locked in.
There is a concept that has been floating around called fecund universe theory. It's been generally regarded as a neat idea but more on the crackpot side of things. This paper is describing a fundamental mechanism necessary for fecund universes. Someone should email this paper to Lee Smolin, he'd get a kick out of it.
We can verify this paper by comparing the outcomes described in the paper with observations of the past of our own universe, and by checking the math in detail, which is not my strong suit. :P Apparently, a consequence of this is the daughter universe 'inside' the black hole inherits its time directionality from the parent universe.
There is also a single 'white hole' (and yes that term IS in the original paper) in the daughter universe which links back to the black hole in the parent universe (a one-way Einstein/Rosen bridge aka wormhole). We would expect to find one and only one such white hole in our own universe, in whatever form it could maintain after surviving the big bang.
No, you cannot traverse this wormhole. If you could enter on this side, you would experience a big bang at ground zero. If you try to enter on the other side, you would be repelled with the force of the big bang, and if you got past it, the parent universe would be at time = infinity, heat death or whatever happens when a universe ends. This is not a highway to other universes unless you are an incredibly exotic form of matter and a time traveler.
There is also a mechanism (not explored) for explaining ratios of dark matter/matter and anti-matter/matter in the resulting universe. The author of this paper has a commendable and rare go-big-or-go-home attitude for attempting to solve most of the unsolved problems in cosmology at once.
As it stands, there are plenty of ways to falsify or confirm the idea, which is always a good thing.
TL;WTF: A black hole is an eternally time-frozen big bang, and a one-way wormhole into a daughter universe that was created from, but contains radically more matter than, what was present inside the event horizon when it formed. Somewhere in the daughter universe, one and only one white hole exists.
This is not a peer reviewed paper. You are looking at a mad scientist's room full of white boards filled with zany ideas, none of which are close to proven or really even rigorously formalized.
If you liked this article, please give it a quick review on ycombinator or StumbleUpon. Thanks