# Question about Quantum Theory regarding hydrogen atom and photon

by euquila
Tags: atom, hydrogen, photon, quantum, theory
 PF Gold P: 1,168 Question about Quantum Theory regarding hydrogen atom and photon It is also fair to say that QM does not describe dynamics of electromagnetic field at all. In Schroedinger's equation, there is nothing corresponding to radiation. No photons. Electromagnetic radiation is addressed by quantum theory of field and there the photons are introduced. But this theory in turn has difficulties describing atoms exactly, so we do not have exact calculation of what happens even for the simplest case like that you mentioned. The answer in quantum theory of fields depends also on how you look at quantum field $A$ (EM field). If you understand it as a probability function that photons will appear somewhere and do something, then (I think) the collapse of A happens instantaneously on the whole spherical surface, because it is only update of our knowledge about the state of the photon. If you think A is something objective independent of the observer, then the collapse cannot be instantaneous in relativistic theory, so, if it happens at all, it has to be continuous process. I am trying to discuss similar question "Are there quantum jumps?" here: http://www.physicsforums.com/showthr...=1#post3832997