  This article presents a global and generalized perspective of electrodynamic
meta-materials formed by space and time engineered modulations, which we name
Generalized Space-Time Engineered Modulation (GSTEM) Metamaterials, or GSTEMs.
In this perspective, it describes metamaterials from a unified spacetime
viewpoint and introduces accelerated metamaterials as an extra type of dynamic
metamaterials. First, it positions GSTEMs in the even broader context of
electrodynamic systems that include (non-modulated) moving sources in vacuum
and moving bodies, explains the difference between the moving-matter nature of
the latter and the moving-perturbation nature of GSTEMs, and enumerates the
different types of GSTEMs considered, namely Space EMs (SEMs), Time EMs (TEMs),
Uniform Space-Time EMs (USTEMs) and Accelerated Space-Time EMs (ASTEMs). Next,
it establishes the physics of the related interfaces, which includes
direct-spacetime scattering and inverse-spacetime transition transformations.
Then, it exposes the physics of the GSTEM metamaterials formed by stacking
these interfaces and homogenizing the resulting crystals; this includes an
original explanation of light deflection by USTEMs as being a spacetime
weighted averaging phenomenon and the demonstration of ASTEM light curving and
black-hole light attraction. Finally, it discusses some future prospects.
Useful complementary information and animations are provided in the
Supplementary Material.
