Black hole cosmology
A black hole cosmology (also called Schwarzschild cosmology or black hole cosmological model) is a cosmological model in which the observable universe is the interior of a black hole. Such models were originally proposed by theoretical physicist Raj Pathria, and concurrently by mathematician I. J. Good.Any such model requires that the Hubble radius of the observable universe be equal to its Schwarzschild radius, that is, the product of its mass and the Schwarzschild proportionality constant. This is indeed known to be nearly the case; at least one cosmologist, however, considers this close match to be a coincidence.In the version as originally proposed by Pathria and Good, and studied more recently by, among others, Nikodem Popławski,
 the observable universe is the interior of a black hole existing as one of possibly many inside a larger parent universe, or multiverse. According to  general relativity, the gravitational collapse of a sufficiently compact mass forms a singular Schwarzschild black hole. In the Einstein–Cartan–Sciama–Kibble theory of gravity, however, it forms a regular Einstein–Rosen bridge, or wormhole.