Science:
A device to protect, or cloak, such objects as oil-drilling
rigs and ships floating on the ocean surface is being developed
by a researcher at the University of California, Berkeley.
Mohammad-Reza Alam, who has published
his
results in
Physical Review Letters, used computer simulations to
test his theory. Because ocean water tends to stratify into a
colder, denser layer below and a warmer, lighter layer above,
waves propagate either along the surface or along the interface
between the two layers. Interfacial waves have much shorter
wavelengths and lower speed than surface waves, so Alam
theorized that before a surface wave reaches a floating object,
he could change the wave into an interfacial one, which would
pass below the object, by introducing a patch of ripples of a
certain wavelength on the sea floor. A second, identical patch
of ripples on the other side of the object would turn the
interfacial wave back into a surface wave. Although the ocean
is much more complicated than the simulations, Alam's novel
approach offers a new twist on cloaking and could inspire a
whole new direction of research.
