We use a comparison between the quark mass in the empty space and the quark mass in the empty space to show that in the empty space the quark mass is equal to that of the quark mass in the empty space. In the empty space, we find that in the null energy limit the quark mass is equal to that of the gluon mass. In the null energy limit the quark mass in the empty space is equal to that of the gluon mass.