From: UFO UpDates - Toronto <post.nul>
Date: Fri, 06 Mar 2009 07:50:37 -0500
Archived: Fri, 06 Mar 2009 07:50:37 -0500
Subject: Closer To Making Invisibility Cloak




Source: PhysOrg.Com - Douglas, Isle Of Man

http://www.physorg.com/news155477880.html

March 5th, 2009


Scientists Closer To Making Invisibility Cloak A Reality

J.K. Rowling may not have realized just how close Harry Potter's
invisibility cloak was to becoming a reality when she introduced
it in the first book of her best-selling fictional series in
1998. Scientists, however, have made huge strides in the past
few years in the rapidly developing field of cloaking. Ranked
the number five breakthrough of the year by Science magazine in
2006, cloaking involves making an object invisible or
undetectable to electromagnetic waves.

A paper published in the March 2009 issue of SIAM Review,
"Cloaking Devices, Electromagnetic Wormholes, and Transformation
Optics," presents an overview of the theoretical developments in
cloaking from a mathematical perspective.

One method involves light waves bending around a region or
object and emerging on the other side as if the waves had passed
through empty space, creating an "invisible" region which is
cloaked. For this to happen, however, the object or region has
to be concealed using a cloaking device, which must be
undetectable to electromagnetic waves. Manmade devices called
metamaterials use structures having cellular architectures
designed to create combinations of material parameters not
available in nature.

Mathematics is essential in designing the parameters needed to
create metamaterials and to show that the material ensures
invisibility. The mathematics comes primarily from the field of
partial differential equations, in particular from the study of
equations for electromagnetic waves described by the Scottish
mathematician and physicist James Maxwell in the 1860s.

One of the "wrinkles" in the mathematical model of cloaking is
that the transformations that define the required material
parameters have singularities, that is, points at which the
transformations fail to exist or fail to have properties such as
smoothness or boundness that are required to demonstrate
cloaking. However, the singularities are removable; that is, the
transformations can be redefined over the singularities to
obtain the desired results.

The authors of the paper describe this as "blowing up a point."
They also show that if there are singularities along a line
segment, it is possible to "blow up a line segment" to generate
a "wormhole." (This is a design for an optical device inspired
by, but distinct from the notion of a wormhole appearing in the
field of gravitational physics.) The cloaking version of a
wormhole allows for an invisible tunnel between two points in
space through which electromagnetic waves can be transmitted.

Some possible applications for cloaking via electromagnetic
wormholes include the creation of invisible fiber optic cables,
for example for security devices, and scopes for MRI-assisted
medical procedures for which metal tools would otherwise
interfere with the magnetic resonance images. The invisible
optical fibers could even make three-dimensional television
screens possible in the distant future. The effectiveness and
implementation of cloaking devices in practice, however, are
dependent on future developments in the design, investigation,
and production of metamaterials. The "muggle" world will have to
wait on further scientific research before Harry Potter's
invisibility cloak can become a reality.

More information: The paper is co-authored by Allan Greenleaf of
the University of Rochester; Yaroslav Kurylev of University
College London; Matti Lassas of Helsinki University of
Technology; and Gunther Uhlmann of the University of Washington.
To read this article in its entirely, visit
http://www.siam.org/journals/sirev/51-1/71682.html

Source: Society for Industrial and Applied Mathematics


[Thanks to 'The Norm' for the lead]



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