Ultra-High Energy Cosmic Rays and Symmetries of Spacetime

2000/12/31 by O. Bertolami
Physics and Astronomy · #astro-ph

paper · pdf

published as Gen.Rel.Grav. 34 (2002) 707-713 · Expanded discussion, 9 pages, plain Latex. This essay was selected for an Honorable Mention by the Gravity Research Foundation, 2001

arxiv created 2001/05/15 · arxiv updated 2009/12/01

Abstract

High energy cosmic rays allow probing phenomena that are inacessible to accelerators. Observation of cosmic rays, presumebly protons, with energies beyond 4 × 10¹⁹ eV, the so-called Greisen-Zatsepin-Kuzmin (GZK) cut-off, give origin to two puzzles: How do particles accelerate to such energies ? Are their sources within 50 - 100 Mpc from Earth, or Lorentz invariance is actually a broken symmetry ?

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