In article <29a2dc35-7ff1-4ba1...@googlegroups.com
israel socratus <socrat...@gmail.com
> Is electron's spin real?
> In 1925, Samuel Goudsmit and George Uhlenbeck claimed that
> some of the mischievous features of the hydrogen spectrum could be
> successfully explained by assuming that electrons act as if they actually have a spin.
> Because electron is spinning with a rotational velocity equivalent to the speed
> of light (which is practically impossible) the only conclusion is that an electron
> can't spin about its own axis, and thus, spin is just a representative term.
> There was a time when we wanted to be told what an electron is.
> The question was never answered. No familiar conceptions can be woven
> around the electron; it belongs to the waiting list.
> --- Sir Arthur Stanley Eddington
> We know electron by what it does, not by what it is.
Of course, an electron is not a tiny hard sphere spinning with an
angular momentum which can be understood with classical physics.
However, spin is not just a label like color in QCD or isospin, but
really has something to do with angular momentum, as is shown by the
Einstein--de Haas effect.