  We consider the behavior of the particles at ultra relativistic energies, for
both the Klein-Gordon and Dirac equations. We observe that the usual
description is valid for energies such that we are outside the particle's
Compton wavelength. For higher energies however, both the Klein-Gordon and
Dirac equations get modified and this leads to some new effects for the
particles, including the appearance of anti particles with a slightly different
energy.
