As you may have noticed, above you will find words for "A small difference between the energy levels 2S_½ and 2P_½ of the hydrogen atom, not predicted by the Dirac equation, whose detection in the Lamb–Retherford experiment of 1947 foreshadowed the development of quantum electrodynamics (in which the discrepancy is explained to be an effect of the emission and re-absorption of virtual photons); such a difference between otherwise expectedly equal energy levels of hydrogen or any other type of atom.". Hover the mouse over the word you'd like to know more about to view its definition. Click to find a better fitting word. Finally, thanks to ChatGPT, the overall results have been greatly improved.