Russo, J. G. (Jorge Guillermo)Townsend, Paul K.2025-05-052025-05-0520242542-4653https://hdl.handle.net/2445/220830Born’s original 1933 theory of nonlinear electrodynamics (in contrast to the later BornInfeld theory) is acausal for strong fields. We explore the issue of strong-field causality violation in families of theories containing Born and/or Born-Infeld, and many variants that have been previously proposed in contexts that include cosmology and black hole physics. Many of these variants are acausal and hence unphysical. A notable exception is the modified Born-Infeld theory with ModMax as its conformal weak-field limit. 1 p.application/pdfengcc-by (c) Russo, J.G. et al., 2024http://creativecommons.org/licenses/by/4.0/Sistemes hamiltoniansElectrodinàmicaHamiltonian systemsElectrodynamicsinfo:eu-repo/semantics/article7571212025-05-05info:eu-repo/semantics/openAccess