I'm trying to fill a conceptual gap I have in the history of physics

In 1922 Stern and Gerlach make their experiment, proving that electrons have intrinsic angular momentum, however it takes a while for people to understand this. At first they think this is somehow caused by quantization of orbital angular momentum, but as the months go by they realize this is not possible

At some point someone does experiments with two magnets, realizing that the beam doesn't split again after identical measurements, but always splits in two after measurements at different angles <- This is the hole I want to fill

Based on the results of these consecutive measurements, Pauli, Sommerfeld, and a few others start proposing a new quantum number that can only take two values

Then in 1925 Ralph Kronig, as well as Uhlenbeck and Goudsmith, independently come up with the idea that this new quantum number is intrinsic angular momentum

Pauli is initially skeptic about this, but ends up embracing the idea and in 1927 publishes a paper containing the Pauli matrices we know and love today

  • $\begingroup$ Could you please be more clear? Gerlach carried out the experiment of Stern, that is why is called Stern–Gerlach experiment. And every SG experiment has two magnets! $\endgroup$
    – Mauricio
    Sep 5 at 14:28


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