The mass lowest limit of a black hole: the hydrodynamic approach to quantum gravity

TL;DR

This paper uses a quantum hydrodynamic approach to derive gravitational equations, suggesting a minimum black hole mass near the Planck scale due to quantum repulsive effects preventing collapse below this limit.

Contribution

It introduces a quantum hydrodynamic framework to analyze black hole formation, revealing a quantum potential that sets a lower mass limit for black holes.

Findings

Quantum potential generates a repulsive force opposing collapse.

Black hole mass cannot be smaller than the Planck mass.

Maximum collapse occurs within a sphere twice the Compton length.

Abstract

In this work the quantum gravitational equations are derived by using the quantum hydrodynamic description. The outputs of the work show that the quantum dynamics of the mass distribution inside a black hole can hinder its formation if the mass is smaller than the Planck's one. The quantum-gravitational equations of motion show that the quantum potential generates a repulsive force that opposes itself to the gravitational collapse. The eigenstates in a central symmetric black hole realize themselves when the repulsive force of the quantum potential becomes equal to the gravitational one. The work shows that, in the case of maximum collapse, the mass of the black hole is concentrated inside a sphere whose radius is two times the Compton length of the black hole. The mass minimum is determined requiring that the gravitational radius is bigger than or at least equal to the radius of the state of maximum collapse.