Born again

by Jorge Russo (ICREA & UB, Barcellona)

Wednesday 22 May 2024, 14:30 → 15:30 Europe/Rome

Room 281 (Physics and astronomy department)

Nonlinear electrodynamics (NLED) theories have wide-ranging applications, from string theory to black holes and cosmology. However, not all proposed NLED theories are physically meaningful. We find that many of these theories, including Max Born’s original 1933 formulation, exhibit causality for weak fields but become acausal under strong fields. Causality imposes stringent constraints, necessitating case-by-case verification. For theories with electromagnetic duality, we find a  simple construction of the general Lagrangian satisfying all causality conditions. We also prove that causality implies both the Dominant Energy Condition (DEC) and, surprisingly, the Strong Energy Condition (SEC). This has important implications for gravitational systems, including regular black holes supported by NLED matter.