Scientists at the University of California, Berkeley have engineered 3-D materials that can reverse the natural direction of visible and near-infrared light. As a result, the research raises the possibility that someday people can use the material in cloaking devices that render objects invisible to the human eye. That type of tactical technology goes well beyond the realm of H.G. Wells and Harry Potter, especially considering that some of the project's funding came from the U.S. Army Research Office and the U.S. Air Force Office of Scientific Research.

However, the researchers cautioned that they are still far off from invisibility cloaks and other applications. Developing a way to manufacture these materials on a large scale will be a challenge, they said.

"Unlike the cloak made famous in the Harry Potter novels, the metamaterials described here are made of metal and are fragile," said the scientists in a statement.

To create invisibility cloaks or shields, material would need to curve light waves completely around an object like a river flowing around a rock, the scientists said. For optical microscopes to discern individual, living viruses or DNA molecules, the resolution of the microscope must be smaller than the wavelength of light.

Two breakthroughs in the development of metamaterials -- composite materials with extraordinary capabilities to bend electromagnetic waves -- are reported separately this week in the Aug. 13 advanced online issue of Nature and in the Aug. 15 issue of Science.

Here is an illustration of how a fish in water is seen by an observer through positive refraction (left), and negative refraction (right), with the squiggly red lines marking the refraction of light and the purple lines representing the path towards the perceived location of the fish, which appears above its actual location.