  Quantum gravity arguments and the entropy bound for effective field theories
proposed in PRL 82, 4971 (1999) lead to consider two correlated scales which
parametrize departures from relativistic quantum field theory at low and high
energies. A simple estimate of their possible phenomenological implications
leads to identify a scale of around 100 TeV as an upper limit on the domain of
validity of a quantum field theory description of Nature. This fact agrees with
recent theoretical developments in large extra dimensions. Phenomenological
consequences in the beta-decay spectrum and cosmic ray physics associated to
possible Lorentz invariance violations induced by the infrared scale are
discussed. It is also suggested that this scale might produce new unexpected
effects at the quantum level.
