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'Electromagnetic Wormhole' Possible with Invisibility Technology
http://www.physorg.com/news111414146.html
7.10.12

One of the views through the "wormhole." Different lengths result
in different bending of light. Credit: University of Rochester
The team of mathematicians that first created the mathematics
behind the "invisibility cloak" announced by physicists last
October has now shown that the same technology could be used to
generate an "electromagnetic wormhole."

In the study, which is to appear in the Oct. 12 issue of Physical
Review Letters, Allan Greenleaf, professor of mathematics at the
University of Rochester, and his coauthors lay out a variation on
the theme of cloaking. Their results open the possibility of
building a sort of invisible tunnel between two points in space.
"Imagine wrapping Harry Potter's invisibility cloak around a tube,"
says Greenleaf. "If the material is designed according to our
specifications, you could pass an object into one end, watch it
disappear as it traveled the length of the tunnel, and then see it
reappear out the other end."

Current technology can create objects invisible only to microwave
radiation, but the mathematical theory allows for the wormhole
effect for electromagnetic waves of all frequencies. With this in
mind, Greenleaf and his coauthors propose several possible
applications. Endoscopic surgeries where the surgeon is guided by
MRI imaging are problematical because the intense magnetic fields
generated by the MRI scanner affect the surgeon's tools, and the
tools can distort the MRI images. Greenleaf says, however, that
passing the tools through an EM wormhole could effectively hide
them from the fields, allowing only their tips to be "visible" at
work.

To create cloaking technology, Greenleaf and his collaborators use
theoretical mathematics to design a device to guide the
electromagnetic waves in a useful way. Researchers could then use
these blueprints to create layers of specially engineered,
light-bending, composite materials called metamaterials.

Last year, David R. Smith, professor of electrical and computer
engineering at Duke's Pratt School, and his coauthors engineered an
invisibility device as a disk, which allowed microwaves to pass
around it. Greenleaf and his coauthors have now employed more
elaborate geometry to specify exactly what properties are demanded
of a wormhole's metamaterial in order to create the "invisible
tunnel" effect. They also calculated what additional optical
effects would occur if the inside of the wormhole was coated with a
variety of hypothetical metamaterials.

Assuming that your vision was limited to the few frequencies at
which the wormhole operates, looking in one end, you'd see a
distorted view out the other end, according the simulations by
Greenleaf and his coauthors. Depending on the length of the tube
and how often the light bounced around inside, you might see just a
fisheye view out the other end, or you might see an Escher-like
jumble.

Greenleaf and his coauthors speculated on one use of the
electromagnetic wormhole that sounds like something out of science
fiction. If the metamaterials making up the tube were able to bend
all wavelengths of visible light, they could be used to make a 3D
television display. Imagine thousands of thin wormholes sticking up
out of a box like a tuft of long grass in a vase. The wormholes
themselves would be invisible, but their ends could transmit light
carried up from below. It would be as if thousands of pixels were
simply floating in the air.

But that idea, Greenleaf concedes, is a very long way off. Even
though the mathematics now says that it's possible, it's up to
engineers to apply these results to create a working prototype.
Greenleaf's coauthors are Matti Lassas, professor of mathematics at
the Helsinki University of Technology; Yaroslav Kurylev, professor
of mathematics at the University College, London; and Gunther
Uhlmann, Walker Family Endowed Professor of Mathematics at the
University of Washington.

Source: University of Rochester