There are basically two types of PARTICLES: BOSONS and fermions. We will talk about that in a bit. We don’t have to worry about it YET. The spatial part of the WAVE functions that we are talking about now will be the same for both types of particles. What is different for different particles (that we are talking about now) is their mass and their electric charge. If they have no mass (e.g. photons), then they have no dispersion which means the phase velocity is the same as the group velocity. If they do have mass then they will have some dispersion.

There are basically two types of particles: bosons and fermions. We will talk about that in a bit. We don’t have to worry about it yet. The spatial part of the wave functions that we are talking about now will be the same for both types of particles. What is different for different particles (that we are talking about now) is their mass and their electric charge. If they have no mass (e.g. photons), then they have no dispersion which means the phase velocity is the same as the group velocity. If they do have mass then they will have some dispersion.