## Spin (physics) |

ofstandard model particle physics of theelementary particles standard model in

andquantum mechanics ,particle physics **spin**is an form ofintrinsic carried byangular momentum , composite particles (elementary particles ), andhadrons .atomic nuclei ^{[1]}^{[2]}spin is one of two types of angular momentum in quantum mechanics, the other being

*orbital angular momentum*. the orbital is the quantum-mechanical counterpart to the classical angular momentum ofangular momentum operator and appears when there is periodic structure to its wavefunction as the angle varies.orbital revolution ^{[3]}^{[4]}the existence of spin angular momentum is from experiments, such as theinferred , in which silver atoms were observed to possess two possible discrete angular momenta despite having no orbital angular momentum.stern–gerlach experiment ^{[5]}in some ways, spin is like a

quantity; it has a definite magnitude, and it has a "direction" (butvector makes this "direction" different from the direction of an ordinary vector). all elementary particles of a given kind have the same magnitude of spin angular momentum, which is indicated by assigning the particle aquantization .spin quantum number ^{[2]}the

of spin is the (si unit ·n ·m ) or (s ·mkg ^{2}·s^{−1}), just as with classical angular momentum. in practice, spin is given as a spin quantum number by dividing the spin angular momentum by thedimensionless ħ, which has the same units of angular momentum, although this is not the full computation of this value. very often, the "spin quantum number" is simply called "spin". the fact that it is a quantum number is implicit.reduced planck constant when combined with the

, the spin of electrons results in thespin–statistics theorem , which in turn underlies thepauli exclusion principle ofperiodic table .chemical elements in 1924 was the first to propose a doubling of electron states due to a two-valued non-classical "hidden rotation".wolfgang pauli ^{[6]}in 1925, andgeorge uhlenbeck atsamuel goudsmit suggested the simple physical interpretation of a particle spinning around its own axis, in the spirit of theleiden university ofold quantum theory andbohr .sommerfeld ^{[7]} anticipated the uhlenbeck-goudsmit model in discussion withralph kronig several months earlier in copenhagen, but did not publish.hendrik kramers ^{[7]}the mathematical theory was worked out in depth by pauli in 1927. when derived hispaul dirac in 1928, electron spin was an essential part of it.relativistic quantum mechanics - quantum number
- magnetic moments
- curie temperature and loss of alignment
- direction
- mathematical formulation
- parity
- applications
- history
- see also
- references
- further reading
- external links

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In **spin** is an ^{[1]}^{[2]}

Spin is one of two types of angular momentum in quantum mechanics, the other being *orbital angular momentum*. The orbital ^{[3]}^{[4]} The existence of spin angular momentum is ^{[5]}

In some ways, spin is like a ^{[2]}

The ^{2}·s^{−1}), just as with classical angular momentum. In practice, spin is given as a

When combined with the

^{[6]} In 1925, ^{[7]} ^{[7]} The mathematical theory was worked out in depth by Pauli in 1927. When