A toy model for a baby universe inside a black hole

• Published in: The European physical journal. C, Particles and fields Vol. 80; no. 5; pp. 1 - 10
• Main Authors: Chakrabarty, Hrishikesh, Abdujabbarov, Ahmadjon, Malafarina, Daniele, Bambi, Cosimo
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-05-2020; Springer; Springer Nature B.V; SpringerOpen
• Subjects: Analysis; Astronomy; Astrophysics and Cosmology; Big Bang theory; Black holes; Elementary Particles; Gravitation; Gravitational collapse; Gravitational effects; Hadrons; Heavy Ions; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Phase transitions; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Regular Article - Theoretical Physics; Specific gravity; String Theory; Universe
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-020-7964-0

We present a dynamical toy model for an expanding universe inside a black hole. The model is built by matching a spherically symmetric collapsing matter cloud to an expanding Friedmann–Robertson–Walker universe through a phase transition that occurs in the quantum-gravity dominated region, here modeled with semi-classical corrections at high density. The matching is performed on a space-like hyper-surface identified by the co-moving time at which quantum–gravity induced effects halt collapse. The purpose of the model is to suggest a possible reconciliation between the observation that black holes are well described by the classical solutions and the fact that the theoretical resolution of space–time singularities leads to a bounce for the collapsing matter.