Assume a system of two hydrogen atoms. No other matter exists inside or outside of the system. Initial condition is one H with an electron in the n=2 state. That state decays to ground and emits EM that is absorbed by the electron on the second H. Repeat forever (maybe). Some questions: Is the "space" occupied by these atoms effectively 1-D with each atom being the end points. I.e. the EM couldn't be emitted outside of those bounds. Would the oscillation continue forever or would it decay somehow? Since there is no reference matter to compare to would it the size of each atom and their distance from each other be undefined? Since the above is undefined then so is the frequency of oscillation? This is not a HW problem. I'm posting this to get a better understanding of the matter/space connection. I wish there was a forum entitled "dumb speculative questions".