Long-range retarded elastic metamaterials: wave-stopping, negative, and hypersonic or superluminal group velocity
This paper investigates new phenomena in elastic wave propagation in metamaterials, characterised
by long-range interactions. The kind of waves borne in this context unveil wave-stopping,
negative group velocity, instability and hypersonic or superluminal effects, both for instantaneous
and for nonlocal retarded actions. Closed form results are presented and a universal propagation
map synthesizes the expected properties of these materials. Perspectives in physics, engineering and
social dynamics are discussed.