= Lamb-Retherford experiment
{c}
{tag=1955 Nobel Prize in Physics}
{title2=1947}
{title2=Lamb shift experiment}
Published as "Fine Structure of the Hydrogen Atom by a Microwave Method" by <Willis Lamb> and Robert Retherford (1947) on <Physical Review>. This one actually has <open accesses> as of 2021, miracle! https://journals.aps.org/pr/pdf/10.1103/PhysRev.72.241
<Microwave> technology was developed in <World War II> for <radar>, notably at the <MIT Radiation Laboratory>. Before that, people were using much higher frequencies such as the <visible spectrum>. But to detect small energy differences, you need to look into longer wavelengths.
This experiment was fundamental to the development of <quantum electrodynamics>. As mentioned at <Genius: Richard Feynman and Modern Physics by James Gleick (1994)> chapter "Shrinking the infinities", before the experiment, people already knew that trying to add <electromagnetism> to the <Dirac equation> led to <infinities in quantum field theory>[infinities] using previous methods, and something needed to change urgently. However for the first time now the theorists had one precise number to try and hack their formulas to reach, not just a philosophical debate about infinities, and this led to major breakthroughs. The same book also describes the experiment briefly as:
> Willis Lamb had just shined a beam of microwaves onto a hot wisp of hydrogen blowing from an oven.
It is two pages and a half long.
They were at <Columbia University> in the <Columbia Radiation Laboratory>. Robert was Willis' graduate student.
Previous less experiments had already hinted at this effect, but they were too imprecise to be sure.
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