  Whenever we consider any relativistic quantum wave equation we are confronted
with the Klein paradox, which asserts that incident particles will suffer a
surplus of reflection when dispersed by a discontinuous potential. Following
recent results on the Dirac equation, we propose a solution to this paradox for
the Klein-Gordon case by introducing virtual beams in a natural well-posed
generalization of the method of images in the theory of partial differential
equations. Thus, our solution considers a global reflection coefficient
obtained from the two contributions, the reflected particles plus the incident
virtual particles. Despite its simplicity, this method allows a reasonable
understanding of the paradox within the context of the quantum relativistic
theory of particles (according to the original setup for the Klein paradox) and
without resorting to any quantum field theoretic issues.
