/sci/ - Science & Math

[Anonymous No.941937]

Somebody please explain a particle having 1/2 spin. How could something going through two full rotations make it look any different than after going through one full rotation?

[Anonymous No.943034]

I am referencing Chemistry for Engineering Students (With Nuclear Chemistry) by Brown and Holme, which states that the spin of +/-1/2 is due to the electron's magnetic moment.

Further research of the magnet moment on wikipedia turned up the following:
Electrons and many elementary particles also have intrinsic magnetic moments, an explanation of which requires a quantum mechanical treatment and relates to the intrinsic angular momentum of the particles as discussed in the article electron magnetic dipole moment. It is these intrinsic magnetic moments that give rise to the macroscopic effects of magnetism, and other phenomena, such as electron paramagnetic resonance.
The magnetic moment of the electron is

where
is the Bohr magneton, S is electron spin,
and the electron g-factor is
in Dirac mechanics, but is slightly larger,
in reality due to quantum electrodynamics effects.
Again it is important to notice that is a negative constant multiplied by the spin, so the magnetic moment is antiparallel to the spin. This can be understood with the following classical picture: if we imagine that the spin angular momentum is created by the electron mass spinning around some axis, the electric current that this rotation creates circulates in the opposite direction, because of the negative charge of the electron; such current loops produce a magnetic moment which is antiparallel to the spin. Hence, a positron (the anti-particle of the electron) with its positive charge has its magnetic moment parallel to its spin.