  We show how Special Relativity sets tight constraints on the form of possible
relations that may exist between the four-momentum of a particle and the wave
four-vector. More specifically, we demonstrate that there is just one way,
according to Special Relativity, to relate the finite energy and momentum of a
corpuscle with the characteristics of a plane wave, frequency, wave vector and
amplitude: that is by laws of direct proportionality like de Broglie equation
and Planck-Einstein equation.
