Consider a hydrogen atom with an electron in some excited state. Now, in order for an electron to drop to a lower state, a photon of a specified energy, which is determined by the energy difference of the two states, must be emitted. Do we know what happens to the electron during this transition? Does the electron physically move to the lower state in a manner that is possibly governed by the laws of relativity? Or, does the electron at the higher energy state cease to exist and a "new" electron comes into existence at the lower energy state in a manner that might be instantaneous? Also, does the emitted photon have a preferential direction, and if so, what determines it?