I have a question regarding the magnetic moment of an atom. If you just have one atom, and you apply an external magnetic field in lets say the z-direction. Then the magnetic moment will precess around the direction of the magnetic field applied, and depending on the quantum numbers it can precess in different quantized directions.
The question is rather simple: WHY does it precess around the magnetic field ? My book only states that it do indeed precess if a magnetic field is applied, but as I'm asking, I'm not sure WHY it does ? Why can't it just point in one direction all the time ?