[SEMINARI]: Dr. Mavromatos: The Quest for Quantum gravity : Testing times for theories?

[Arcadi Santamaria]

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PLEASE, NOTICE THE CHANGE OF TITLE AND ABSTRACT 
OF THE SEMINAR BY DR. MAVROMATOS
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                              S E M I N A R I

        [Image]        Departament de Física Teòrica         [Image]
                  Universitat de València - IFIC (UV-CSIC)
                      46100 Burjassot (València) Spain

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           The Quest for Quantum gravity : Testing times for theories?

                              Dr. N. Mavromatos

                          (King's College, London)

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                     Aula de Seminaris de Física Teòrica
                  Thursday 09 of March of 2000 at 11:30 AM
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                                    Resum

  A satisfactory model for quantum gravity may necessitate a completely new
 perception for space time at sub-Planckian (length) scales, which may even
    have a cellular (foamy) structure. After a brief introduction to some
 theoretical models (including string and brane theories) I discuss physical
   consequences of such cellular (foamy) structures for the propagation of
   low-energy matter. In particular I argue that there may be non-trivial
     `optical' properties of the quantum-gravity `medium'resulting in a
   non-trivial index of refraction and other stochastic effects as far as
   propagation of, say, massless particles is concerned. The phenomenon is
     analogous to light dispersion by atoms in the air, but the crucial
 difference is that the phenomenon becomes stronger the higher the energy of
  the probe is, which may be qualitatively understood by the fact that high
  energy probes cause a bigger `distortion' of the space time fluid. Given
  that such effects build up the further the particle probe travels thorugh
    the foam, it becomes apparent that the most sensitive probes of such
potential quantum-gravity effects should be astrophysical. I detail one such
example, light from Gamma-Ray-Bursters (GRB) the majority of which are known
      to date to be at cosmological distances from earth. I discuss how
quantum-gravity phenomenology can be done using such probes. Some discussion
 on other tests of quantum gravity foam (both terrestrial and astrophysical
    (such as high-energy neutrinos from cosmic rays) can be given if time
                                  allows.

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