The proton radius has been measured for many years to be 0.88 fm, with experiments using electron-proton scattering and by using atomic spectoscopy to look at the Lamb shift
seen by an orbiting electron, a shift which depends on the proton radius .
Willis Lamb, using highly sensitive microwave techniques developed at the Columbia Radiation Laboratory during the war, made precise measurements of the spectrum of hydrogen and found that they disagreed with predictions of Dirac's theory by about one part in 1,000 (this is known as the Lamb shift
By precisely measuring the wavelengths of these X-rays, the researchers could calculate a quantity known as the Lamb shift
, a small change in atomic energy levels caused by interactions between electrons bound to a nucleus but still moving around.
To investigate the question Muller and Schafer chose two physical effects at extreme ends of the range of our perception, the Lamb shift
in atomic hydrogen and the precession of planetary orbits.
I do not want to amble in relativistic fields of creation and annihilation operators, and vacuum fluctuations, spontaneous emmission and Lamb shifts
. Though I am drawn, I have been away too long.