"That’s true if you look at the propagating component of light waves. But light also records smaller sub-wavelength details in its evanescent components, which do not propagate. At least not usually. What [John] Pendry showed [about 10 years ago] was that evanescent components can propagate in a material with a negative refractive index, and he pointed out that a thin film of silver ought to have just the right properties. Since then, the race has been on to build superlenses. In 2005, Nicolas Fang at the University of Illinois at Urbana-Champaign created one that could record details as small as one-sixth of a wavelength. That was a significant improvement over the diffraction limit, but why not better?" - Steven Perez from Bookmarklet