Hey all, I'm currently in my second QM class, and I have a question about the emission of photons. Last semester, as we studied the wavefunction of a hydrogen electron, the professor briefly mentioned that the energy levels correspond to the observed energies of photons emitted from hydrogen atoms. In general, however, an electron will be in a linear combination of the eigenstates. Since the photon energies are only measured to be discrete, does this mean that the emission of a photon corresponds with a measurement of the electron's energy? NB: I haven't learned QED yet, so please give me a dumbed-down answer. Thanks.