Ciro Santilli @cirosantilli 35

Richard Feynman Quantum Electrodynamics Lecture at University of Auckland (1979) mentions it several times.

This was one of the first two great successes of quantum electrodynamics, the other one being the Lamb shift.

In youtu.be/UKbp85zpdcY?t=52 from freeman Dyson Web of Stories interview (1998) Dyson mentions that the original key experiment was from Kusch and Foley from Columbia University, and that in 1948, Julian Schwinger reached the correct value from his calculations.

Apparently first published at The Magnetic Moment of the Electron by Kusch and Foley (1948).

Bibliography:

Adds special relativity to the Schrödinger equation, and the following conclusions come basically as a direct consequence of this!

Experiments explained:

Experiments not explained: those that quantum electrodynamics explains like:See also: Dirac equation vs quantum electrodynamics.

The Dirac equation is a set of 4 partial differential equations on 4 complex valued wave functions. The full explicit form in Planck units is shown e.g. in Video 1. "Quantum Mechanics 12a - Dirac Equation I by ViaScience (2015)" at youtu.be/OCuaBmAzqek?t=1010:Then as done at physics.stackexchange.com/questions/32422/qm-without-complex-numbers/557600#557600 from why are complex numbers used in the Schrodinger equation?, we could further split those equations up into a system of 8 equations on 8 real-valued functions.

Extremely precocious, borderline child prodigy, he was reading Dirac at 13-14 from the library.

He started working at night and sleeping during the moring/early afternoon while he was at university.

He was the type of guy that was so good that he didn't really have to follow the university rules very much. He would get into trouble for not following some stupid requirement, but he was so good that they would just let him get away with it.

Besides quantum electrodynamics, Julian worked on radar at the Rad Lab during World War II, unlike most other top physicists who went to Los Alamos Laboratory to work on the atomic bomb, and he made important contributions there on calculating the best shape of the parts and so on.

He was known for being very formal mathematically and sometimes hard to understand, in stark contrast to Feynman which was much more lose and understandable, especially after Freeman Dyson translated him to the masses.

However, QED and the men who made it: Dyson, Feynman, Schwinger, and Tomonaga by Silvan Schweber (1994) does emphacise that he was actually also very practical in the sense that he always aimed to obtain definite numbers out of his calculations, and that was not only the case for the Lamb shift.

2s/2p energy split in the hydrogen emission spectrum, not predicted by the Dirac equation, but explained by quantum electrodynamics, which is one of the first great triumphs of that theory.

Note that for atoms with multiple electrons, 2s/2p shifts are expected: Why does 2s have less energy than 1s if they have the same principal quantum number?. The surprise was observing that on hydrogen which only has one electron.

Initial experiment: Lamb-Retherford experiment.

On the return from the train from the Shelter Island Conference in New York, Hans Bethe managed to do a non-relativistic calculation of the Lamb shift. He then published as The Electromagnetic Shift of Energy Levels by Hans Bethe (1947) which is still paywalled as of 2021, fuck me: journals.aps.org/pr/abstract/10.1103/PhysRev.72.339 by Physical Review.

The Electromagnetic Shift of Energy Levels Freeman Dyson (1948) published on Physical Review is apparently a relativistic analysis of the same: journals.aps.org/pr/abstract/10.1103/PhysRev.73.617 also paywalled as of 2021.

TODO how do the infinities show up, and how did people solve them?

www.mdpi.com/2624-8174/2/2/8/pdf History and Some Aspects of the Lamb Shift by G. Jordan Maclay (2019)

Currently an informal name for the Standard Model

Chronological outline of the key theories:

Experiments explained by QED but not by the Dirac equation:

Sponsored by National Academy of Sciences, located in Long Island.

Some photos at: www.nasonline.org/about-nas/history/archives/milestones-in-NAS-history/shelter-island-conference-photos.html on the website of National Academy of Sciences, therefore canon.

This is where Isidor Rabi exposed experiments carried out on the anomalous magnetic dipole moment and Willis Lamb presented his work on the Lamb shift.

It was a very private and intimate conference, that gathered the best physicists of the area, one is reminded of the style of the Solvay Conference.

QED and the men who made it: Dyson, Feynman, Schwinger, and Tomonaga by Silvan Schweber (1994) chapter 4.1 this conference was soon compared to the First Solvay Conference (1911), which set in motion the development of non-relativistic quantum mechanics.

A single line in the emission spectrum.

So precise, so discrete, which makes no sense in classical mechanics!

Has been the leading motivation of the development of quantum mechanics, all the way from the:

The principal quantum number thing fully determining energy is only true for the hydrogen emission spectrum for which we can solve the Schrödinger equation explicitly.

For other atoms with more than one electron, the orbital names are just a very good approximation/perturbation, as we don't have an explicit solution. And the internal electrons do change energy levels.

Note however that due to the more complex effect of the Lamb shift from QED, there is actually a very small 2p/2s shift even in hydrogen.