{(Extract: Particle Spin)}[1st July 1988]

[Redbook5:199][19880701.1753c]{(Extract: Particle Spin)}[1st July 1988]

.1753

[continued]

'Every type of elementary particle has a definite value for its spin, either integral (e.g. light quanta) or half-integral (e.g. electrons, protons, neutrinos). Particles with half-integral spin obey Fermi-Dirac statistics; those with integral spin obey Bose-Einstein statistics, which differ in form as u/(1+u) differs from u/(1-u) – u being any function.* The conformity to law that underlies the Fermi-Dirac statistics for electrons was first recognised by Wolfgang Pauli and formulated as the Pauli exclusion principle, which played a decisive role in settling upon the shell structure in the periodic system of the elements.

'The basic duality of waves and corpuscles** is of universal significance for all kinds of elementary particles, even for composite particles in those experiments that cannot lead to a breakup of the particles into their component parts.'***

*It seems that the value of Spin is more like rotational symmetry than actual rotation. <880806>

**[This is (or was) a recognised term in this context, although perhaps a little old-fashioned nowadays. <20180622>]

***E[nyclopedia ]B[ritannica] XXV[.678ff 'Philosophy of Nature',], 682

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