  Surface plasmons at metal interfaces are collective excitations of the
conduction electrons and the electromagnetic field. They exist in "curved
three-dimensional space-times" defined by the shape of the metal surface and
the spatial distribution of the dielectric constant near the surface. Here we
show that surface plasmon toy models of many non-trivial space-time metrics,
such as wormholes and black holes, can be easily built and studied in
experiments. For example, a droplet of dielectric on the metal surface behaves
as a black hole for surface plasmons within a substantial frequency range. On
the other hand, a nanohole in a thin metal membrane may be treated as a
wormhole connecting two "flat" surface plasmon worlds located on the opposite
interfaces of the membrane.
