Such a scenario in which the universe is born from inside a wormhole (also called an Einstein-Rosen Bridge) is suggested in a paper from Indiana University theoretical physicist Nikodem Poplawski in Physics Letters B.
The Einstein-Cartan-Kibble-Sciama theory of gravity provides a simple scenario in early cosmol-
ogy which is alternative to standard cosmic inflation and does not require scalar fields. The torsion of spacetime prevents the appearance of the cosmological singularity in the early Universe filled with Dirac particles averaged as a spin fluid. Instead, its expansion starts from a state at which the Universe has a minimum but finite radius. We show that the dynamics of the closed Universe immediately after this state naturally solves the flatness and horizon problems in cosmology because of an extremely small and negative torsion density parameter, 10^−69. This scenario also suggests that the contraction of our Universe preceding the state of minimum radius could correspond to the dynamics of matter inside the event horizon of a newly formed black hole existing in another universe.
Well, a spinning black hole would have imparted some spin to the space-time inside it, and this should show up as a “preferred direction” in our universe, says Poplawski. Such a preferred direction would result in the violation of a property of space-time called Lorentz symmetry, which links space and time. It has been suggested that such a violation could be responsible for the observed oscillations of neutrinos from one type to another
As the universe in a black hole expands to infinity, the boundary of the black hole becomes an Einstein-Rosen bridge connecting this universe with the outer universe. We recently suggested that all astrophysical blackholes may be Einstein-Rosen bridges (wormholes), each with a new univserse inside that formed simultaneously with the black hole. Accordingly, our own Universe may be the interior of a black hole existing in another universe, and the time asymmetry of motion at the boundary of this black hole may cause the perceived arrow of cosmic time. This description is possible because the torsion of spacetime, which is produced by the intrinsic spin of fermions, prevents the formation of singularities. Thus the gravitational collapse of a star composed of quarks and leptons to a black hole does not create a singularity, allowing matter inside the event horizon to reexpand. Since most stars rotate, most astrophysical black holes are rotating black holes. A universe born from a rotating black hole should inherit its preferred direction, related to the axis of rotation.
The proposed description of the origin of our Universe may explain the arrow of time. Although the laws of the ECKS theory of gravity are time-symmetric, the boundary conditions of the Universe are not, because the motion of matter through the event horizon of a black hole is unidirectional and thus it can define the arrow of time. The arrow of cosmic time of a universe inside a black hole would then be fixed by the time-asymmetric collapse of matter through the event horizon, before the subsequent expansion. Such an arrow of time would also be entropic: although black holes are states of maximum entropy in the frame of outside observers, new universes expanding inside black holes would allow entropy to increase further.