In my post title, "
B" is a common reference to magnetism, while "
2" refers to "double".
"The magnetic moment of an electron is approximately twice what it should be in classical mechanics. The factor of two implies that the electron appears to be twice as effective in producing a magnetic moment as the corresponding classical charged body." –
Wikipedia This is also true for muons and all fundamental fermions with electric charge. It is embodied in their spin g-factors, (a.k.a. "
g_{s}" with the subscript for "spin-½").
g_{s} is very nearly 2. A "g-factor" is obviously a factor, but in the case of
g_{s}, it's a
fudge factor to force calculation to match observation.
I mention this because Lincoln surprisingly doesn't, despite its prominence in the video's title. What's going on is this. No one in physics actually knows why
g_{s} is 2. Classically,
g = 1 is used merely for unit conversion. So, to avoid embarrassment, physicists talk about the minutia remaining after subtracting 2 from
g_{s}. Thus, "
The physics of g – 2".
I'm not saying decimal place minutia isn't important (it does relate to the fine structure constant,
α after all). It's just that it seems the proverbial cart is getting in front of the horse. So, once again, here's what's wrong (and how it's Phyxed).
The spin magnetic moment (
μ_{s}) is given by an equation with proportionality constant
g_{s} over the reduced Planck constant (
ħ). However,
ħ = h/2pi, which means the Planck constant is reduced by dividing it by a
classical rotation (i.e.
2pi radians). This is
ridiculous, considering that physicists beat into the heads of poor grad students that fermion spin is NOT classical. In fact, it's experimentally proven that fermions return to their exact initial state after a
double rotation (i.e.
4pi radians).
"
…physical effects of the difference between the rotation of a spin-½ particle by 360° as compared with 720° have been experimentally observed in classic experiments in neutron interferometry. In particular, if a beam of spin-oriented spin-½ particles is split, and just one of the beams is rotated about the axis of its direction of motion and then recombined with the original beam, different interference effects are observed depending on the angle of rotation. In the case of rotation by 360°, cancellation effects are observed, whereas in the case of rotation by 720°, the beams are mutually reinforcing." -
Wikipedia My point is that for spin-½, the Planck constant must be reduced by
4pi rather than
2pi. Then the mysterious need for
g_{s} = 2 disappears.
- It's no coincidence that 4pi radians and 4pi steradians accomplish the same resolution of the mysterious spin g-factor. It is consistent with intrinsic spin occurring in a 3-plane about a temporal axis (i.e. as chronaxial spin).