Recently, I heard someone saying that even when an electron exists in an orbital around an atom it is still emitting electromagnetic (EM) radiation. Of course, from a classical perspective, I was told that when an electron orbits the nucleus of an atom it would eventually collide with the nucleus because it would be radiating EM waves. Now I also know that it is wrong to say that an electron is orbiting the nucleus, but are electrons 'still' emitting EM radiation even if it is not in an excited state? If so, what kind of radiation is this?
There are some related questions and answers about this subject. So it appears that a non-excited electron would not be radiating EM radiation. Most of the answers are based on a theory (QED). However, isn't it possible to just measure whether a non-exited atom is radiating?
