In a Leonard Susskind video lecture at http://www.youtube.com/watch?v=VtBRKw1Ab7E&feature=relmfu at 8:30 minutes he talks about an electron entering a strong magnetic field will precess, in fact does a demo of the precession with a stick. He states that the precession will end with radiated energy from the electon. Later on around 17:00 he talks about the setup of an electron at 45 degrees in a strong magnet, then sending the electron through a magnet at 0 degrees. He is very emphatic that only one photon of a very specific wavelength (and no other radiated energy) may or may not be detected depending on whether the electon was "flipped". This seems to be a contridiction. Clearly, based on the first part of the lecture, the electron will start to precess when it enters the second magnetic setup, but where is the photon (radiated energy) associated with the ending of the precession? Where is the evidence the electron has stopped precessing?