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Attractive and repulsive light force

  1. Jul 15, 2009 #1
    http://www.sciencedaily.com/releases/2009/07/090713131556.htm

    I'm confused...photons have no charge and no mass. This article seems to say there is an attractive and repulsive force between photons, but that can't be electromagnetic and it can't be gravity..so what are they talking about?
     
  2. jcsd
  3. Jul 15, 2009 #2

    Born2bwire

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    Well, there is a radiation pressure from light. Photons still have a momentum despite not having any mass and the transfer of the momentum will result in a force. But the article specifically states that these forces are not the product of radiation pressure so I think one would need to read the journal article to find out the specific mechanism.
     
  4. Jul 16, 2009 #3

    Andy Resnick

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    I agree- the article is not exactly clear. It is claimed the force is a different effect from laser tweezers (which is casued by induced dipoles), but no information about their model is presented in that website.
     
  5. Jul 16, 2009 #4

    ZapperZ

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    Here is the full abstract of this paper:

    So it definitely appears that (i) this is a guided EM wave (ii) it is then similar to Casimir effect of bounded wave (iii) it is analogous to the "bonding" and "antibonding" state that we get in chemical bonds that depends on the phase of the wavefunction.

    Reading the paper quickly, it definitely appears that this is a purely classical effect. It has nothing to do with a photon having attractive or repulsive force.

    Zz.
     
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