The universe as a closed anisotropic universe born in a black hole

TL;DR

This paper explores a model where our universe originated inside a black hole within Einstein--Cartan gravity, suggesting torsion and particle production can lead to a nonsingular bounce and subsequent inflation, explaining current observations.

Contribution

It introduces a novel scenario where the universe emerges from a black hole, incorporating torsion and particle production to avoid singularities and produce inflation.

Findings

Torsion can prevent singularities via a bounce.

Particle production can trigger inflation after the bounce.

The universe can isotropize and resemble current observations.

Abstract

We consider a universe formed in a black hole in the Einstein--Cartan theory of gravity. The interior of a Schwarzschild black hole can be represented by the Kantowski--Sachs metric that describes a closed anisotropic universe. We use this metric to derive the field equations with a relativistic spin fluid as a source. We show that torsion may prevent a singularity and replace it with a nonsingular bounce if particle production dominates over shear. Particle production after the last bounce can generate a finite period of inflation, during which the universe expands and isotropizes to the currently observed state. Our universe might have therefore originated from a black hole.