Events

Date: 22 September 2026   Time: 14:00 - 15:30     

Location: MB503

NOTE: Pre talk intro for non experts starts at 2pm, with seminar starting at 2.30pm

Title: Negative refraction and gravitational metamaterials: From optical geometry to dark matter

Abstract: In this talk I propose a novel reinterpretation of spacetime as an effective optical medium capable of exhibiting negative refraction. I show that this phenomenon is not a coordinate artifact, but rather a covariant property of energy-momentum flow, arising when phase propagation and energy transport become oppositely directed. I argue that such a regime is forbidden in minimally coupled general relativity and instead requires non-minimal disformal couplings, which induce an intrinsically anisotropic optical geometry. Within this framework, spacetime can support localized, finite-energy configurations that emerge directly from its optical structure. These objects, which I identify as gravitational metamaterials, behave as particle-like excitations whose effective dynamics, in the weak-field limit, naturally reproduces cold dark matter phenomenology. This suggests a new perspective in which dark matter is not a fundamental component but an emergent geometric manifestation with exotic optical properties. To test this paradigm, I discuss how negative refraction modifies gravitational lensing, potentially leading to observable signatures that distinguish these configurations from standard compact objects and their mimickers.