Wormholes on Earth?

According to a group of mathematicians, it may be possible to create devices with internal tunnels that are invisible to detection by electromagnetic waves—wormholes, in a sense. The group discusses the idea in a paper published in the October 29 online edition of Physical Review Letters. The scientists say that by custom designing the values of two parameters that describe electromagnetic (EM) materials, the electrical permittivity and magnetic permeability, around and inside a cylinder, a novel optical device could be produced. Essentially, most of the device would be invisible to detection by external EM radiation of a certain frequency, with only the ends of the cylinder being visible and accessible to the EM waves. “The chosen values for the permittivity and permeability would cause the coating to manipulate EM waves in a way that is not seen in nature,” explained University of Rochester mathematician Allan Greenleaf, one of the paper's authors, to PhysOrg.com. Permittivity is a measure of a material's readiness to become electrically polarized in response to an applied electric field (how well it “permits” the field). Permeability describes how magnetized a material becomes when a magnetic field is applied. Modern EM materials known as metamaterials allow theoretical designs, such as a wormhole, to be physically constructed, at least in principle. Greenleaf and his colleagues, Yaroslav Kurylev of University College in London, Matti Lassas of the Helsinki University of Technology, and Gunther Uhlmann of the University of Washington, use the word “wormhole” in more of a mathematical sense than physical.

That is, the devices would act as wormholes from the viewpoint of Maxwell's equations, the four fundamental equations that describe the relationship between electric fields, magnetic fields, electric charge, and electric current. For any other frequencies than those for which the permittivity and permeability were designed, the tunnel region would look roughly like a solid cylinder.