1. Visible light cloak: a light bending fabric that renders a cloaked object invisible to the human eye from any viewing angle. Made from a rigid synthetic polymer composed of tiny rods spaced about 350 nanometers apart. Researchers laid the cloak over a flat surface with a small bump in the middle. The cloak bent incoming light rays around the bump and bounced them back as if they had struck a flat surface. Observers would never know the bump existed. For now, it can only hide small imperfections on flat surfaces.
2. Sound cloak: Stacked sheets of one-millimeter thick perforated plastic. Placed over a 10cm long block of wood the cloak bent sound waves heading toward the block so that they avoided the cloaked area and rebounded as if it were not there. If the block had ears, it would not have heard any sound from outside the cloak. Sonic cloaks could steer sound waves around beams and columns in a concert hall to give every seat perfect acoustics.
3. Earthquake cloak: A blueprint for seismic cloaks that could protect buildings from earthquakes, made of giant concrete cylinders, 60 to 200 feet in diameter, each drilled with small holes to manipulate seismic waves. The cylinders would be installed underground, arranged to encircle a building's foundation. As the cylinders deflect the seismic waves they would also absorb some of the waves' energy and convert it into heat and sound. The cloaked building would vibrate barely at all, while buildings around it would experience a weakened temblor.
4. Water cloak: A means of cloaking ships as they move through the water. A network of small water-deflecting blades and pumps encasing the bottom of the ship. It would scoop up water in front of the bow, steer it around the ship and release it behind the stern. The result: the ship would glide through the water without disturbing it. Cloaked ships could move faster and be harder to spot.
*Discover Magazine Special Issue



