When light passes from air to water, it is refracted. This refraction is dependent upon the index of refraction of water, which is basically the ratio of the speed of light in air to its speed in water. Scientists have demonstrated a negative index of refraction in a material. The material are composites which show unusual electromagnetic properties. The new composites consist of wires and cut rings of copper inside a fiberglass sheet, arranged in square boxes. When microwaves strike on this material, they refract in the opposite direction to that in all other materials ( Science , 292, p77).