I've been reading about nuclear magnetic resonance, and one aspect is bothering me. (I haven't studied quantum physics yet.) Quantum mechanically, the proton has only 2 energy states: spin +1/2 spin and spin -1/2. In NMR, a pulse of electromagnetism is applied to alter the orientation of the proton, ie. in a classical sense, to alter the angle between the axis of the spinning proton and the direction of the external magnetic field. Texts write of angles of 90 degrees, 60 degrees, 30 degrees etc... But what do these various angles represent in a quantum sense? I thought the proton can only be in one of 2 different states (+1/2 and -1/2)???