We interpret the de Broglie frequency in terms of a harmonic oscillato
r model applied to a material particle. The amplitude of the force cou
ld be thought of as the particle self-gravitational interaction, when
its mass fluctuates in position through a distance equal to the Planck
length, The reason for proposing this model is the following: in orde
r to compare in an unambiguous way the undulatory properties of a part
icle of nonzero rest mass with the photon, we need to consider a chara
cteristic speed of the material particle from among the various possib
le ''speed states'' in which this particle can be found. The model is
also used as a means of comparing the relative strengths of the gravit
ational, electric, and strong nuclear forces.