To: WSFAlist at keithlynch.net
Date: Sun, 3 Nov 2002 21:16:21 -0500
Subject: [WSFA] on the Casimir front
From: ronkean at juno.com
Reply-To: WSFA members <WSFAlist at keithlynch.net>

Experiment Could Reveal "Extra Dimensions," Exotic Forces
http://www.sciencedaily.com/releases/2002/10/021030073527.htm
[27]Purdue University
Date: 10/31/2002

   WEST LAFAYETTE, Ind. -- Physicists have devised a new experiment that
   will be used in the quest for exotic forces in nature and "additional
   spatial dimensions."

   The researchers have demonstrated an innovative way to measure a
   phenomenon known as the Casimir effect -- findings that also could
   have implications for the design of microscopic machines that contain
   tiny parts on the size scale of nanometers -- or billionths of a
   meter.

   The scientists are taking their theoretical findings a step further by
   conducting an experiment to prove that the theory works, said Ephraim
   Fischbach, a professor of physics at Purdue University.

   A paper that describes the theory for the experiment will appear in
   the Nov. 4 issue of Physical Review Letters, a journal published by
   the American Physical Society. The paper was written by Fischbach and
   Dennis E. Krause, a professor of physics at Wabash College, in
   Crawfordsville, Ind.

   The Casimir effect, predicted in 1948 by Dutch physicist Hendrick
   Casimir, is a force that pushes together two plates of metal placed
   near each other in empty space -- or a vacuum. The closer the plates
   are to each other, the stronger the force.

   What may be thought of as empty space is actually teeming with
   fleeting particles and electromagnetic fields. However, because the
   plates are so close to each other, many of the particles and fields
   cannot get between the plates. That means the space surrounding the
   plates contains more particles and energy than the space between the
   plates. The more energy-dense space surrounding the plates exerts a
   force on the metal, pushing the plates together.

   The strength of the Casimir effect depends on the number of electrons
   in the metal out of which the plates are made. For that reason, the
   Purdue physicists will test the effect using plates made of isotopes
   of the same metal. Isotopes are elements that contain the same number
   of electrons but different numbers of neutrons in the atom's nucleus.

   One portion of the experiment will use plates made out of nickel 58,
   an isotope of nickel that contains 28 protons and 30 neutrons in its
   nucleus. A second portion of the experiment will use plates made of
   nickel 64, which contains 28 protons and 36 neutrons.

   Because the plates made of nickel 58 and 64 have the same number of
   electrons, the Casimir forces acting on both sets of plates will be
   nearly identical. That means any measurable difference in force
   between the two sets of plates must be attributed to some entirely
   new, as-yet undiscovered force acting on the respective nuclei.

   Such knowledge could prove critical in the design of future devices
   containing tiny gears and motors that are measured in nanometers.
   Because these devices will contain moving parts placed extremely close
   to one another, they may be subjected to exotic forces that do not
   affect the parts inside large-scale machines.

   "When you actually make little gears, for example, they may stick
   together in funny ways," Fischbach said. "You can't just make a
   microscopic version of your car's transmission and expect it to work.
   Suddenly, on such small size scales, when moving parts are very close
   to one another, a lot of funny things happen.

   "In order to go from fundamental physics to applied nanotechnology,
   you really will have to understand the laws that govern what happens
   at a very small scale. This research helps to bridge the gap between
   very fundamental physics and really applied physics."

   The discovery of new forces, could, in turn, provide evidence for the
   existence of additional dimensions beyond the three spatial dimensions
   of length, width and height.

   "A new kind of gravity-like force would be the fingerprint of the fact
   that we may really live in a world that is more than three spatial
   dimensions," Fischbach said. "You wouldn't see this force over large
   distances, but you could see it over small distances."

   However, scientists must first devise a way to confidently measure the
   Casimir force.

   "Physicists know that the Casimir force exists," Fischbach said. "But
   we have to now understand it sufficiently well that we can say, 'I
   know when I line up the plates exactly like this, that I should see a
   certain force, which I can measure, and if I see something different,
   then there might be a new force on top of the Casimir force.'"

   Because nickel 58 and 64 have the same number of electrons but
   different nuclei, any difference in forces observed between the two
   sets of plates could provide evidence that those nuclei were
   interacting with "extra dimensions" that exist side-by-side with the
   known three dimensions, Fischbach said.

   Scientists have proven the existence of four fundamental forces of
   nature: gravity; electromagnetism; the strong force, which holds the
   nucleus of the atom together; and the weak force, which governs the
   energy production in stars and is responsible for some forms of
   radioactivity.

   Researchers have theorized that the universe contains additional
   dimensions beyond the three spatial dimensions observed in the
   everyday world. Theory also has suggested that, of the four known
   fundamental forces of nature, all but one -- gravity -- are confined
   to three dimensions. This could help to explain why gravity is weaker
   than the other forces.

   "In a sense, gravity gets dissipated by being spread out over more
   dimensions, and that's why gravity looks weak compared to the other
   forces," Fischbach said. "Gravity might sense and interact with these
   extra dimensions in such a way as to reveal their presence.

   "The point is that gravity actually penetrates these other
   dimensions."

   Previous research by Fischbach has suggested the existence of a
   so-called "fifth force" of nature. If other dimensions do exist, a
   gravity-like "fifth force" might be used to study and communicate with
   those dimensions, Fischbach said.

   Fischbach and Krause have worked recently with Ron Reifenberger, a
   Purdue professor of physics, and Stephen W. Howell, a postdoctoral
   research associate in the Department of Physics. They are now
   collaborating with two experimentalists, Ricardo Decca, a professor of
   physics at Indiana University-Purdue University Indianapolis, and
   Daniel Lopez, a scientist who is a member of the Nanofabrication
   Research Lab at Lucent Technologies.

   The experiment currently being designed by the team will use
   nanofabrication techniques to replace one of the plates in the above
   experiment with a tiny sphere. The remaining plate with the nickel
   coatings will be attached to a "microelectromechanical torsion
   oscillator," a setup that could be likened to a nanometer-scale
   version of a record player in which the record player's needle is the
   sphere. The device will record the force between the sphere and the
   plates, searching for a difference in the forces on the two nickel
   isotopes.

   The research has been funded by the U.S. Department of Energy.

   Editor's Note: The original news release can be found [28]here.
     _________________________________________________________________

   Note: This story has been adapted from a news release issued for
   journalists and other members of the public. If you wish to quote any
   part of this story, please credit Purdue University as the original
   source. You may also wish to include the following link in any
   citation:

References

  27. http://www.purdue.edu/

.

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