Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Giovanni Amelino testing QG

  1. Feb 17, 2004 #1


    User Avatar
    Gold Member


    A perspective on Quantum Gravity Phenomenology1
    Giovanni Amelino-Camelia
    aDipart. Fisica, Univ. Roma \La Sapienza” and INFN Sez. Roma1
    P.le Moro 2, 00185 Roma, Italy
    I give a brief overview of some Quantum-Gravity-Phenomenology research lines, focusing on studies of cosmic rays and gamma-ray bursts that concern the fate of Lorentz symmetry in quantum spacetime. I also stress that the most valuable phenomenological analyses should not mix too many conjectured new features of quantum spacetime, and from this perspective it appears that it should be dicult to obtain reliable guidance on the quantum-gravity
    problem from the analysis of synchrotron radiation from the Crab nebula and from the analysis of phase coherence of light from extragalactic sources. Forthcoming observatories of ultra-high-energy neutrinos should provide several opportunities for clean tests of some simple hypothesis for the short-distance structure of spacetime. In particular, these neutrino studies, and some related cosmic-ray studies, should provide access to the regime E> mEp.
    1 Quantum Gravity Phenomenology
    Quantum-gravity research used to be completely detached from experiments. The horrifying smallness of the expected quantum-gravity e ects, due to the overall suppression by powers
    of the ratio of the Planck length (Lp ~ 10-35m) versus the characteristic wavelength of the particles involved in the process, had led to the conviction that experiments could never
    possibly help. But recently there has been a sharp change in the attitude of a signi cant fraction of the quantum-gravity community. This is reflected also by the tone of recent
    quantum-gravity reviews (see, e.g., Refs. [[1,2,3,4])]as compared to the tone of quantum gravity reviews published up to the mid 1990s (see, e.g., Ref. [[5, 6]]).
    The fact that the smallness of an e ect does not necessarily imply that it cannot be studied experimentally is not actually a new idea. There are several examples in physics, and even
    remaining in the context of fundamental physics there is the noteworthy example of studies of the prediction of proton decay within certain granduni ed theories of particle physics.
    The predicted proton-decay probability is really small, suppressed by the fourth power of the ratio between the mass of the proton and the granduni cation scale [mproton=Egut]4 ~ 10-64 ,
    but in spite of this truly horrifying suppression, with a simple idea we have managed to acquire an excellent sensitivity to the new e ect. The proton lifetime predicted by granduni ed theories is of order 1039s and \quite a few” generations of physicists should invest their
    i thought this might be interesting, some may have read it already
    sorry about the quality of reproduction.
    Last edited: Feb 17, 2004
  2. jcsd
  3. Feb 18, 2004 #2


    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    this is the best survey article in Quantum Gravity Phenomenology
    (testing QG theories by observation) so far, as far as I know

    here is an alternative link, to the one wolram gave

    http://arxiv.org/gr-qc/0402009 [Broken]

    Giovanni A-C chaired the first QG session of last July's
    "Tenth Marcel Grossmann Meeting on General Relativity"
    which was on QG testing
    and he gave a summary talk which basically defines the field
    and tells where it is and what the prospects are

    to me this says that currently this paper that wolram linked us to is the definitive mainstream word on testing QG theories

    so where does Jerzy Kowalski-Glikman fit in
    a slightly belligerant looking young man in a motorcycle jacket (see his website)

    http://www.ift.uni.wroc.pl/JK-G/ [Broken]

    well he fits in at the footnote at the bottom of page 5
    down below equation (3)

    and in that footnote his work is somewhat overshadowed by
    Amelino-Camelia's own work

    be that as it may Jerzy K-G also gave a paper at that session of Tenth Marcel Grossmann and my private opinion of K-G is very high
    Last edited by a moderator: May 1, 2017
  4. Feb 18, 2004 #3


    User Avatar
    Gold Member

    the large boost high velocity regime, seems to be an
    important aspect in testing QG, i am attempting to
    understand this area of research, i am not sure if it
    will provide an answer, given that there is so many
    unknowns of the properties of planck scale, but it may
    be an interesting path to follow.
  5. Feb 18, 2004 #4


    User Avatar
    Gold Member


    Abstract. We consider the implications for laser interferometry of the quantum-gravity-motivated modifications in the laws of particle propagation, which are presently being considered in attempts to explain puzzling observations of ultra-high-energy cosmic rays. We show that there are interferometric set-ups in which the Planck-scale effect on propagation leads to a characteristic signature. A naive estimate is encouraging with respect to the possibility of achieving Planck-scale sensitivity, but we also point out some severe technological challenges which would have to be overcome in order to achieve this sensitivity.
    as i am not a member i can not get the full article, anyone have an
    Last edited by a moderator: Apr 20, 2017
  6. Feb 18, 2004 #5


    User Avatar
    Gold Member


    Constraints on possible Lorentz symmetry violation (LV) of order E/M_Planck for electrons and photons in the framework of effective field theory (EFT) are discussed. Using (i) the report of polarized MeV emission from GRB021206 and (ii) the absence of vacuum \v{C}erenkov radiation from synchrotron electrons in the Crab nebula, we improve previous bounds by 10^-10 and 10^-2 respectively. We also show that the LV parameters for positrons and electrons are different, discuss electron helicity decay, and investigate how prior constraints are modified by the relations between LV parameters implied by EFT.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook