[tt] the physics arXiv blog

[Eugen Leitl]

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From: the physics arXiv blog <howdy at arxivblog.com>
Date: Fri, 11 Jul 2008 14:14:47 -0500 (CDT)
To: eugen at leitl.org
Subject: the physics arXiv blog
Reply-To: the physics arXiv blog <howdy at arxivblog.com>


[1]the physics arXiv blog

   [2]If invisibility cloaks don't work, try the invisibility sheet

   Posted: 11 Jul 2008 01:17 AM CDT

   [3]Invisibility sheet 

   When it comes to invisibility cloaks, nobody has done more to advance
   the field than John Pendry, a theoretical physicist at Imperial
   College, London. It was he who suggested the idea in the first place
   and mapped out how one could be built in theory. He even got his hands
   dirty by  collaborating with the team of engineers who first built a
   working cloak.

   So when he pronounces on the subject, we sit up and listen.

   Pendry has clearly been worrying about the limitations  of
   invisibility cloaks. For a start, they work only in the microwave part
   of the spectrum and at a single specific freqeuncy. (Optical
   invisibility cloaks seem as far away as ever because of problems with
   light absorption.)

   The cloaks must be made of exotic materials with properties that vary
   throughout their structure and are in any case unobtainable in nature
   and so have to be designed and made by hand.

   The resulting cloaks are not perfect and probably never will be. To
   hide an object completely, the permittivity and permeability of these
   metamaterials must take infinite values at some points.

   So what to do? Pendry argues in a paper on the arxiv that instead of
   making objects invisible, you can hide them just as well by making
   them look like a flat conducting sheet. An eminently sensible
   suggestion.

   The advantage of this approach, he calculates, is that it readily
   works for visible light and over a wide range of frequencies. What's
   more, it can be done with ordinary materials that are available today.

   All that's needed is to hide your object under a material that he
   calls an isotropic dielectric. He's even done a number of simulations
   to show how such a material would make anything it covers look like a
   flat conducting sheet.

   Pendry doesn't bother with the practical details of how to make an
   isotropic dielectric material. But maybe he doesn't need to. He
   wouldn't by any chance be referring to water, would he?

   Ref: [4]arxiv.org/abs/0806.4396: Hiding Under the Carpet: a New
   Strategy for Cloaking

   [5][arXivblog?i=3LkgIx] 
   [6][arXivblog?i=0FIg3J] [7][arXivblog?i=wn87XJ]
   [8][arXivblog?i=4LitPj] [9][arXivblog?i=crsmXJ]
   [10][arXivblog?i=pPHW2j] [11][arXivblog?i=Qv4hiJ]
   [12][arXivblog?i=uEc1xj] [13][arXivblog?i=vRpqmJ] 
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References

   1. http://arxivblog.com/
   2. http://feeds.feedburner.com/~r/arXivblog/~3/332418170/
   3. http://arxivblog.com/wp-content/uploads/2008/07/invisibility-sheet.jpg
   4. http://arxiv.org/abs/0806.4396
   5. http://feeds.feedburner.com/~a/arXivblog?a=3LkgIx
   6. http://feeds.feedburner.com/~f/arXivblog?a=0FIg3J
   7. http://feeds.feedburner.com/~f/arXivblog?a=wn87XJ
   8. http://feeds.feedburner.com/~f/arXivblog?a=4LitPj
   9. http://feeds.feedburner.com/~f/arXivblog?a=crsmXJ
  10. http://feeds.feedburner.com/~f/arXivblog?a=pPHW2j
  11. http://feeds.feedburner.com/~f/arXivblog?a=Qv4hiJ
  12. http://feeds.feedburner.com/~f/arXivblog?a=uEc1xj
  13. http://feeds.feedburner.com/~f/arXivblog?a=vRpqmJ
  14. http://arxivblog.com/
  15. http://www.feedburner.com/fb/a/emailunsub?id=8632699&key=kesJ612ZsV
  16. http://feeds.feedburner.com/arXivblog
  17. http://feeds.feedburner.com/arXivblog

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Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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