Emergent electromagnetism

TL;DR

This paper introduces the concept of emergent electric fields within a modified electromagnetism framework, linking it to emergent gravity, and demonstrates its role in resolving black hole singularities.

Contribution

It formulates a novel theory of electromagnetism with emergent electric fields and couples it to emergent gravity, providing new insights into black hole singularity resolution.

Findings

Emergent electric fields can be distinguished from fundamental ones in observations.

The modified theory allows for nonsingular black hole solutions.

Coupling emergent electromagnetism with gravity resolves singularities.

Abstract

We introduce the concept of emergent electric field. This is distinguished from the fundamental one in that the emergent electric field directly appears in observations through the Lorentz force, while the latter enters the phase space as the canonical momentum of the electromagnetic field. In Hamiltonian classical electromagnetism this concept naturally appears after introducing the topological $\theta$ term. Furthermore, we show that in the spherically symmetric model the concept of emergent electric field allows us to formulate a modified theory of electromagnetism that is otherwise impossible. The relation between the fundamental and the emergent electric fields is derived from the imposition of general covariance of the electromagnetic strength tensor, which is a nontrivial task in the canonical formulation the modified theory is based on. We couple this theory to emergent modified gravity, where a similar distinction between spacetime and gravity is made such that the spacetime, which defines the observable geometry, is an emergent field composed of the fundamental gravitational field. In this more encompassing emergent field theory coupling gravity and electromagnetism, we show that the spherically symmetric model contains a nonsingular black hole solution where not only modified gravity but also modified electromagnetism is crucial for a robust singularity resolution and to avoid the existence of (super)extermal black holes.