Michio Kaku Quote

In general, the internal structures implanted inside the metamaterial must be smaller than the wavelength of the radiation. For example, microwaves can have a wavelength of about 3 centimeters, so for a metamaterial to bend the path of microwaves, it must have tiny implants embedded inside it that are smaller than 3 centimeters. But to make an object invisible to green light, with a wavelength of 500 nanometers (nm), the metamaterial must have structures embedded within it that are only about 50 nanometers long-and nanometers are atomic-length scales requiring nanotechnology. (One nanometer is a billionth of a meter in length. Approximately five atoms can fit within a single nanometer.) This is perhaps the key problem we face in our attempts to create a true invisibility cloak. The individual atoms inside a metamaterial would have to be modified to bend like a snake.