A team of physicists at the Autonomous University of Barcelona, Spain, has constructed and experimentally demonstrated a magnetic wormhole – an object that allows electromagnetic wave propagation between two points in space through an invisible tunnel.

Wormholes are fascinating cosmological objects that can connect two distant regions of the Universe.

Constructing an artificial gravitational wormhole is an apparently unrealizable challenge. Large amounts of negative gravitational energy would be required, which makes impossible its realization with present technology.

In 2007, Prof Allan Greenleaf of the University of Rochester and co-authors presented a theoretical proposal for designing a wormhole for electromagnetic waves.

Prof Alvaro Sanchez from the Autonomous University of Barcelona’s Department of Physics and his colleagues used metamaterials and metasurfaces to build the wormhole experimentally, so that the magnetic field from a source, such as a magnet or an electromagnet, appears at the other end of the wormhole as an isolated magnetic monopole.

“The magnetic wormhole is an analogy of gravitational ones, as it changes the topology of space, as if the inner region has been magnetically erased from space,” said Prof Sanchez, senior author of a paper published in the journal Scientific Reports.

The wormhole in this experiment is a sphere made of different layers: an external layer with a ferromagnetic surface, a second inner layer, made of superconducting material, and a ferromagnetic sheet rolled into a cylinder that crosses the sphere from one end to the other.

The sphere is made in such a way as to be magnetically undetectable – invisible, in magnetic field terms – from the exterior.

“We experimentally show that the magnetic field from a source at one end of the wormhole appears at the other end as an isolated magnetic monopolar field, creating the illusion of a magnetic field propagating through a tunnel outside the 3D space,” Prof Sanchez and co-author wrote in the paper.

“Practical applications of the results can be envisaged, including medical techniques based on magnetism.”

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Jordi Prat-Camps et al. 2015. A Magnetic Wormhole. Scientific Reports 5, article number: 12488; doi: 10.1038/srep12488