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New Class off Materials with negative Eps and Mu



Interesting article from the "weird science" forum...

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---------- Forwarded message ----------
Date: Wed, 22 Mar 2000 23:39:43 +0200
From: hamdi ucar <hamdix@verisoft.com.tr>
To: freenrg <freenrg-l@eskimo.com>, vortex <vortex-l@eskimo.com>
Subject: New Class off Materials with negative Eps and Mu

(Repost)
http://ucsdnews.ucsd.edu/newsrel/science/mccomposite.htm

They say the material is composed of copper rings. Not so unusual. - hamdi ucar


UCSD PHYSICISTS DEVELOP NEW CLASS OF COMPOSITE MATERIALS WITH 'REVERSED'
PHYSICAL PROPERTIES NEVER BEFORE SEEN

Minneapolis, MN-Physicists at the University of California, San Diego have
produced a new class of composite materials with unusual physical
properties that scientists theorized might be possible, but have never
before been able to produce in nature.

The remarkable achievement, detailed in a paper that will appear in a
forthcoming issue of Physical Review Letters, was announced here today at
a meeting of the American Physical Society. The UCSD physicists said they
expect their discovery to open up a new subdiscipline within physics and
produce an array of commercial applications for this material, on which
the university has applied for a patent.

"Composite materials like this are built on a totally new concept," said
the two co-leaders of the UCSD team, Sheldon Schultz and David R. Smith,
who announced their discovery at a news conference. "While they obey the
laws of physics, they are predicted to behave totally different from
normal materials and should find interesting applications."

The unusual property of this new class of materials is essentially its
ability to reverse many of the physical properties that govern the
behavior of ordinary materials. One such property is the Doppler effect,
which makes a train whistle sound higher in pitch as it approaches and
lower in pitch as it recedes. According to Maxwell's equations, which
describe the relationship between magnetic and electric fields, microwave
radiation or light would show the opposite effect in this new class of
materials, shifting to lower frequencies as a source approaches and to
higher frequencies as it recedes.

Similarly, Maxwell's equations further suggest that lenses that would
normally disperse electromagnetic radiation would instead focus it within
this composite material. This is because Snell's law, which describes the
angle of refraction caused by the change in velocity of light and other
waves through lenses, water and other types of ordinary material, is
expected to be exactly opposite within this composite.

"If these effects turn out to be possible at optical frequencies, this
material would have the crazy property that a flashlight shining on a slab
can focus the light at a point on the other side," said Schultz. "There's
no way you can do that with just a sheet of ordinary material."

He notes that the development of this new class of materials, which was
financed by the National Science Foundation and the Department of Energy,
is entirely consistent with the laws of physics and was predicted as a
possibility in 1968 by a Russian theorist, V.G. Veselago. "But until now,"
Schultz adds, "no one had the material, so it couldn't be verified."

Underlying the reversal of the Doppler effect, Snell's law, and Cerenkov
radiation (radiation by charged particles moving through a medium) is that
this new material exhibits a reversal of one of the "right-hand rules" of
physics which describe a relationship between the electric and magnetic
fields and the direction of their wave velocity.

The new materials are known by the UCSD team colloquially as "left-handed
materials," after a term coined by Veselago, because they reverse this
relationship. What that means is physically counterintuitive-pulses of
electromagnetic radiation moving through the material in one direction are
composed of constituent waves moving in the opposite direction.

The UCSD physicists emphasized that while they believe their new class of
composites will be shown to reverse Snell's law, the specific composite
they produced will not do so at visible-light frequencies. Instead, it is
now limited to transmitting microwave radiation at frequencies of 4 to 7
Gigahertz-a range somewhere between the operation of household microwave
ovens (3.3 Gigahertz) and military radars (10 Gigahertz).

However, Schultz said the UCSD team will soon be attempting to verify that
a composite constructed on similar principles will be able to focus and
disperse microwaves in exactly the opposite manner as normal lenses. "We
did not do this experiment yet," he said. "But this is what the equations
predict. Physicists will understand that if our data presented in our
paper are correct, given Maxwell's equations, then this will be the
result."


The idea for the new composite came from Smith, building on the work of
John Pendry of Imperial College, London. In 1996, Pendry described a way
of using ordinary copper wires to create a material with the property
physicists call "negative electric permittivity." Electric
permittivity-often referred to as the "dielectric constant"-is the
response of a material to electromagnetic radiation.

"When you take a material like plastic, glass or sapphire and you shine
microwaves onto it, you can characterize how the microwaves going through
it will behave by a parameter called electric permittivity," explained
Schultz. Most known materials in nature have a positive electric
permittivity.

Pendry also recently suggested a way of using copper rings to make a
material with negative magnetic permeability at microwave frequencies.
Just about all of the magnetic materials in nature, those that respond to
magnetic rather than electric fields, have what physicists call a
"positive magnetic permeability."

What's unusual about the new class of materials produced by the UCSD team
is that it simultaneously has a negative electric permittivity and a
negative magnetic permeability, a combination of properties never before
seen in a natural or man-made material.

"And the interesting thing is that it's produced with no magnetic
material," said Schultz. "It's all done with copper."

"The bottom line," said Smith, "is that this material-this metamaterial,
at frequencies where both the permittivity and permeability are negative,
behaves according to a left-handed rule, rather than a right-handed rule."

# # #

David Smith can be reached March 20-22 in Minneapolis at 612-331-1900.

Sheldon Schultz can be reached March 20-23 in Minneapolis at 612-333-4545

Messages for the UCSD scientists can also be left at the APS meeting
pressroom at 612-335-6735, 6736, 6737, 6738. Pressroom Hours: Mon.-Wed.
8AM to 5PM, Thurs. 8AM to noon. The news conference will take place at 1
p.m. March 21 at the Minneapolis Convention Center, Room 203B.