  This research aims to consider a new principle of symmetry in the space-time
by means of the elimination of the classical idea of rest including a universal
minimum limit of speed in the subatomic world. Such a limit, unattainable by
the particles, represents a preferred inertial reference frame associated with
a cosmological background field that breaks Lorentz symmetry. So there emerges
a modified relativistic dynamics with a minimum speed related to the Planck
length of the early universe, which leads us to search for a quantum gravity at
low energies.
