  Lower-dimensionality at higher energies has manifold theoretical advantages
as recently pointed out. Moreover, it appears that experimental evidence may
already exists for it - a statistically significant planar alignment of events
with energies higher than TeV has been observed in some earlier cosmic ray
experiments. If this alignment is not a fluke, then the LHC should be able to
see effects associated with the dimensional crossover. Further,
(2+1)-dimensional spacetimes have no gravitational degrees of freedom, and
gravity waves cannot be produced in that epoch in the early universe. This
places a universal maximum frequency at which primordial gravity waves can
propagate, which may be accessible to future gravitational wave detectors such
as LISA. In this talk, the theoretical motivation for "vanishing dimensions" as
well as generic experimental and observational signature will be discussed.
