When quantum electrodynamics, the quantum field theory of electrons and photons, was being developed after World War II, one of the major challenges for theorists was calculating a value for the Lamb ...
A spectral transition of hydrogen atoms resonates with CMB photons at a wavelength of 21 centimeters as they pass through, distorting the CMB black body spectrum and providing a way to probe the ...
In addition to shifting and splitting described so far, the hydrogen‐like atomic spectra exhibit shifting and splitting originated by interactions between the electron and the nucleus.