TITLE: What makes an electron-proton barrier?
QUESTION [0 upvotes]: An electron (negative charge) and a positron (positive charge) annihilate in pure energy. For an electron and a proton it is all similar, the different charge, the mutual attraction and the emission of EM radiation.
What is the mechanism by which an electron and a proton do not annihilate, but stop their approach at some distance?
To confine the answers, please do not refer to statements such as that the calculated energy levels are stable states. This is a consequence of the initial observations; the corresponding calculations only reflect the observations.

REPLY [2 votes]: As has been already said, the proton is not the anti-particle of the electron. Now, in your post, you say that electron and positron annihilate. Actually what we call "an electron" is a special excitation of what we call "electron/positron field". When you solve the Dirac equation for hydrogenoïds it is very clear that what we call an electron is in fact not just the two first components of the field. So "negative excitation" annihilates with its positive counterpart. There has never been any reason for the electron to annihilates with the proton. Particles do not annihilate because they have the opposite charge. They annihilate because they are particle/anti-particle counterpart (think of the neutrinos: no charge but annihilates with the anti-neutrino).
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