GREAT ideas are often both simple and elegant. Such was the
suggestion made five years ago by Sir John Pendry of Imperial
College London that a perfect lens—free from any distortion or
loss of information—could be created if it were possible to
build materials that possessed certain surprising properties. On
November 17th, researchers unveiled a significant step towards
making such materials for visible light.  When a ray of light
crosses a boundary, such as that between air and a block of
glass, its path is altered. In the case of air and glass, the
light is bent towards the boundary. It is this bending, along
with using a curved surface, that is exploited to create the
traditional lenses used in cameras, telescopes and microscopes.
Conventional lenses can never be perfect because they always
fail to refocus the light that comes from the object under
investigation in the form of decaying waves. The image thus
cannot contain the information about the object carried by these
waves.  The extent to which the lig