[HN Gopher] The Mystery of Spin
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       The Mystery of Spin
        
       Author : cratermoon
       Score  : 11 points
       Date   : 2022-11-26 19:36 UTC (1 days ago)
        
 (HTM) web link (www.math.columbia.edu)
 (TXT) w3m dump (www.math.columbia.edu)
        
       | BMc2020 wrote:
       | _There's no mystery here about what the spin angular momentum is:
       | all one has done is used the proper definition of the angular
       | momentum as infinitesimal generator of rotations and taken into
       | account the fact that in this case rotations also act on the
       | vector values, not just on space. One can easily generalize this
       | to tensor-valued wave-functions by using the matrices for
       | rotations on them, getting higher integral values of the spin._
       | 
       | Well, Duh.
        
         | the__alchemist wrote:
         | I'd prefer to see less use of "all one has done", "just",
         | "easily", and "trivial".
        
         | wnoise wrote:
         | I know you're being sarcastic, but this is actually just table-
         | stakes for any sort of research in fundamental physics. This is
         | quite analogous to linear momentum being the generator of
         | translation, yet having mysterious components in E&M that
         | aren't a particle moving, but charge interacting with the
         | somewhat inscrutable "vector potential".
        
         | [deleted]
        
       | quickthrower2 wrote:
       | If I understand the point of the article it is:
       | 
       | a. Not worth understanding the mysteries.
       | 
       | b. Electrons have spin classically, so no need to talk about
       | Quantum Field Theory
       | 
       | And then posts some equations about spin.
       | 
       | I presume (a) is because we would get into "God" territory and
       | (b) is to make the discussion simpler.
        
         | tinym wrote:
         | No, the mysteries that "are deep, hard to understand, and not
         | worth the effort" are why Scientific American is publishing
         | this junk article. My lay theory is that SA hasn't been worth
         | reading in decades and basically nobody can write well about
         | quantum mechanics for a casual audience..
        
       | mhh__ wrote:
       | Tomonagas book "the story of spin" is a banger. Really gentle at
       | times but very detailed and insightful at other times
        
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       (page generated 2022-11-27 23:00 UTC)