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Cosmic Physics: the High Energy Frontier (by Floyd Stecker)

  1. Dec 19, 2003 #1

    marcus

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    this is a really good survey of all the cosmic ray and gammaray burst news, and the new detectors planned, with some interesting physical discussion of the processes involved

    It is 54 pages, but only about 50 of that is text.
    Floyd Stecker may be the or one of the top experts in this area. He looks like he's about 60 years old and still having fun. Born in the Bronx (in the 1940s I guess), recipient of several awards etc. also
    has co-authored with Glashow.

    the survey
    "Cosmic Physics: the High Energy Frontier" is at
    http://arxiv.org/astro-ph/0309027

    it has brief sections on testing LV (lorentz invariance violation) which explicitly assume that LV involves having a preferred frame
    The more I read in this area the more I get the impression that this is what high-energy astronomers think LV means (!), implying that their current work has little or no bearing on LQG, which was constructed not to break Lorentz invariance in that sense---and does not imply a preferred frame.

    Apparently G. Amelino-Camelia at one time had a version of DSR that had a preferred frame, but no version of LQG I've ever heard of has had one! When you look up the references in Stecker to where he says some forms of "quantum gravity" suggest a preferred frame you see that he references slightly old DSR papers by G. A-C. and a paper by Glashow in the 1990s. He does not point to any actual LQG papers to illustrate his point. (I dont think there would likely be any, but if you go back far enough who knows.)

    It is an excellent paper though. In case anyone is curious, sections 2.6.3 and 3.10 on pages 17 and 32 have some discussion of Lorentz invariance breaking---with the analysis based on assuming a preferred frame. This is how approaches to testing "quantum gravity" are discussed.

    I recommend this to all and sundry. High energy astronomy is probably what is taking over from accelerators as defining where new physics will develop. The particle and gammaray energies being observed are fantastic----particle energies inferred by the fireworks they set off are up in the peta- and exa- electronvolts. So it is worth finding out about and this paper gives a good way in.
     
    Last edited: Dec 19, 2003
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  3. Dec 19, 2003 #2

    Nereid

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    neutrinos too

    It's not just gammas, protons, nuclei etc ..

    At least one detector (AMANDA II) will also, it is hoped, explore high energy (mere TeV ) neutrinos.

    The Stecker paper explores this regime too.
     
  4. Dec 19, 2003 #3

    marcus

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    Re: neutrinos too

    right you are! and he puts in a good word for neutrinos whereas that the universe is opaque to high-energy light but transparent to high-energy neutrinos---they are better for seeing the early U in his view IIRC
     
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