Scientists at the University of Pennsylvania have devised a possible new method to make an invisibility shield. The researcher's proposed "plasmonic screen" would prevent light from bouncing off an object, dramatically reducing its visibility. According to an article in News@Nature, there are many caveats regarding Star Trek-esque applications, but the theory still seems to hold water:
For visible-light shielding, says (scientist Nader) Engheta, nature has already provided suitable plasmonic materials: silver and gold. To reduce the scattering of longer-wavelength radiation such as microwaves, one could make the shield from a 'metamaterial': a large-scale structure with unusual electromagnetic properties, typically constructed from arrays of wire loops and coils.
(Scientist Andrea) Alù and Engheta's calculations show that spherical or cylindrical objects coated with such plasmonic shields do indeed produce very little light scattering. It is as though, when lit by light of the right wavelength, the objects become extremely small, so small that they cannot be seen.
UPDATE: I did say there were caveats, but several readers were quite disappointed after reading in the full article that only microscopic particles could be made invisible to the naked eye.
