A big part of the fun of this blogging gig (for me at least) is watching stories resurface and reiterate themselves over time. Point in case: metamaterials and ‘invisibility cloaks’, which cropped up a few times last year, and which raise their head again with news from Hong Kong University that researchers have discovered a theoretical method for not only making things appear invisible, but also for making one thing appear to be another thing entirely. Confused? Well, this might help:
The trick is to create a material in which the permittivity and permeability are complementary to the values in a nearby region of space containing the mouse we want to hide. “Complementary” means that the material cancels out the effect that the mouse has on a plane lightwave passing through. So a plane wave would be bent by the mouse but then bent back into a plane as it passes through the complementary material, making the mouse disappear.
The second step is to then distort this plane wave in the way that an elephant would. This means creating transformational material that distorts a plane lightwave in the same way as an elephant. So anybody looking at this mouse would instead see an elephant.
An invisibility cloak is just a special case of this, when the mouse is simply replaced by the illusion of free space, say Chan and co.