Bending light through water or other media is high school science, hardly a subject that would appear to be controversial. But what happens to light in very special media that have a negative index of refraction is currently being hotly debated in leading physics journals and preprints. Ordinary materials such as glass lenses bend light so that the refracted ray is on the opposite side of the "normal," the imaginary line perpendicular to the surface of the medium. In a negative index material, also known as a left-handed material, light is refracted back on the same side of the normal. According to John Pendry of Imperial College, London, an ideal slab of such a material would act like a perfect lens, creating an image that would include details well below the stopping point for conventional lenses, called the diffraction limit. It sounds too good to be true, but for each complaint raised, proponents of negative index materials have at least a partial answer.
This article was originally published with the title Heat and Light.