Not really, no. Re (a), the mysteries that Woit says are not worth understanding are the ones described in the parenthesis at the end of the first paragraph. (

Not really, no. Re (a), the mysteries that Woit says are not worth understanding are the ones described in the parenthesis at the end of the first paragraph. (As far as I can tell from reading the actual paper Woit links to, he is being nice about how off base the paper actually is.) As he notes in the second paragraph, the actual story--i.e., how spin actually works in QM--is worth understanding. Re (b), Woit is not saying electrons have spin classically, he's saying electrons (and other quantum particles) have spin in non-relativistic QM, or more precisely that spin can be modeled in non-relativistic QM, so the claim made by Sebens and Carroll that QFT is needed to understand spin is wrong. (AFAIK the key contribution QFT makes is the spin statistics connection, which is a different issue that is not discussed in the article.) The equations Woit posts are a basic presentation of how spin can be modeled in non-relativistic QM.