Editing Lamb shift (section)

==In the hydrogen spectrum==
{{Main|Lyman series}}
In 1947, [[Hans Bethe]] was the first to explain the Lamb shift in the [[hydrogen spectrum]], and he thus laid the foundation for the modern development of [[quantum electrodynamics]]. Bethe was able to derive the Lamb shift by implementing the idea of mass renormalization, which allowed him to calculate the observed energy shift as the difference between the shift of a bound electron and the shift of a free electron.<ref name=BetheEmagShift>
{{cite journal |last=Bethe|first=H. A.|date=1947|title=The Electromagnetic Shift of Energy Levels|url=http://link.aps.org/doi/10.1103/PhysRev.72.339|journal=Phys. Rev.|volume=72|issue=4|pages=339–341|bibcode=1947PhRv...72..339B|doi=10.1103/PhysRev.72.339|s2cid=120434909 |url-access=subscription}}
</ref> The Lamb shift currently provides a measurement of the [[fine-structure constant]] α to better than one part in a million, allowing a [[Precision tests of QED|precision test of quantum electrodynamics]].

His calculation of the Lamb shift has been stated to have revolutionized quantum electrodynamics and having "opened the way to the modern era of [[particle physics]]".<ref name=":0" />