Since the first theoretical cloaking papers in 2006, the topic of optical invisibility has just gotten stranger and stranger. There have been proposals of optical wormholes, perfect optical illusions, space-time cloaks, and more. Perhaps even more surprising, however, is the speed at which practical implementations of a number of ideas have been achieved. Consider, for instance, this short video of a macroscopic optical invisibility cloak, a small-scale version of an object demoed at TED 2013 by physics professor Baile Zhang:
Impressive, is it not? This device is the implementation of a cloaking idea introduced in 2008* and described colorfully as “hiding under the carpet!” It holds the most promise in the short term for being able to effectively hide macroscopic (larger than microscopic) objects.
But what is a “carpet cloak,” and how does it work? To answer this, we delve back into the weird optics of cloaking devices, and their design using theoretical warpings of space!




