Lamb Shift

In physics, the Lamb shift, named after Willis Lamb (1913–2008), is a small difference in energy between two energy levels and (in term symbol notation) of the hydrogen atom in quantum electrodynamics (QED). According to Dirac, the and orbitals should have the same energies. However, the interaction between the electron and the vacuum causes a tiny energy shift on . Lamb and Robert Retherford measured this shift in 1947, and this measurement provided the stimulus for renormalization theory to handle the divergences. It was the harbinger of modern quantum electrodynamics developed by Julian Schwinger, Richard Feynman, and Shinichiro Tomonaga. Lamb won the Nobel Prize in Physics in 1955 for his discoveries related to the Lamb shift.