Well, usually in quantum mechanics, as in classical physics, we are free to set the zero of energy anywhere we want, and consequently redefine the speed of phase rotation. It doesn't make a difference to the calculated results. But all that changes if we are going to study general relativity. With the approximations we're making, we might as well call it mc 2 . Now consider the effects of variations in time .
Time goes a little faster at the top of the helix than at the bottom.
Eventually it unwinds completely and starts to wind up again in the opposite direction. The top goes faster than the bottom, and starts to get ahead. Now the wave function has unwound completely. The top keeps rotating ahead of the bottom. It is now wound in the opposite direction.