Precise and creative control of material below the wavelength of a radiation (like visible light 390 to 780 nanometers) can be used to create invisibility. Better nanoprecise materials help facilitate this. radio and radar wave invisibility is projected for 18 months and visible light in 5 years.
Pendry and his co-authors also propose using metamaterials because they can be tuned to bend electromagnetic radiation - radio waves and visible light, for example - in any direction. A cloak made of those materials, with a structure designed down to the submicroscopic scale, would neither reflect light nor cast a shadow.
Instead, like a river streaming around a smooth boulder, light and all other forms of electromagnetic radiation would strike the cloak and simply flow around it, continuing on as if it never bumped up against an obstacle. That would give an onlooker the apparent ability to peer right through the cloak, with everything tucked inside concealed from view.
Already the scientists are a long way towards the easier goal of creating a cloak that can render objects invisible to radar or radio waves. Both have longer wavelengths than visible light, making them less challenging to work with.
"We are confident we can build a cloak that will work for radar within 18 months," said Prof Pendry, one of the authors of a research paper published today in the journal Science.
Here is the abstract at the journal Science, on Metamaterials and Negative Refractive Index. the article discusses the potential that these materials may hold for realizing new and seemingly exotic electromagnetic phenomena.
Here is some background on metamaterials