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In simplest terms, what is null dust?

  1. Oct 26, 2009 #1
    The links I pull up assume that the reader knows what null dust is. Which I don't. An explanation would be appreciated.
    The question came up when looking for an (equally absent) clear explanation of Vaidya spacetime.
    This, in turn, came up while looking at the article http://prola.aps.org/abstract/PRD/v70/i10/e101502; perhaps also could someone tell me whether this is just a rerun of the outmoded "white hole" construction?
     
  2. jcsd
  3. Oct 26, 2009 #2

    George Jones

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    Null dust is a pressureless fluid (the dust part) that has lightlike streamlines (the null part).

    For the Vaidya spacetime, take a look at sections 4.3.5 and 5.1.8 in Eric Poisson's notes,

    http://www.physics.uoguelph.ca/poisson/research/agr.pdf.

    Better yet, see if your library has a copy of the excellent book, A Relativist's Toolkit: The Mathematics of Black Hole Mechanics, into which the notes evolved.

    Your prola link doesn't work, and I have access to prola. Can you find an arXiv link?
     
  4. Oct 26, 2009 #3

    cristo

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    There's a stray semicolon at the end of that link. The correct one is: http://prola.aps.org/abstract/PRD/v70/i10/e101502
     
  5. Oct 26, 2009 #4
    Thanks, George Jones and Christo.
    George Jones: I have downloaded the Poisson book on GR, and will be looking working through the sections you mentioned. Thank you for your book recommendation, but I presently have no access to a decent academic library. Christo answered about the link.
     
  6. Oct 26, 2009 #5

    George Jones

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    No. A wormhole need exotic stuff to hold it open, and this example uses radiation with negative energy density.

    arXiv link:

    http://arxiv.org/abs/gr-qc/0406080.
     
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