Fontem paginae Constans structurae subtilis inspicere

{{Capsa tabellaria
	|; Constans structurae subtilis
	| Dimensiones: [[Quantitas sine dimensionibus|Nulla dimensio]]
	| Magnitudo: 0.0072973525693<br /><small>(vel ∼ {{ofrac|137.035999084}})</small>
}}

[[Fasciculus:Fabry Perot Etalon Rings Fringes.png|right|thumb|upright=1|Haec {{Creanda|en|Wave interference|d|Q136980|interferentia}} (per {{Creanda|en|Fabry–Pérot interferometer|d|Q1359945|interferometrum Fabryanum–Perotianum}} capta) {{Creanda|en|Fine structure|d|Q1402041|structura subtilis|structuram subtilem}} atomi {{Creanda|en|Deuterium|d|Q102296|deuterium|deuterii}} ostendit.]]

{{Res|Constans structurae subtilis}}{{Convertimus}} vel {{Res|constans Sommerfeldiana}} ({{mvar/phyalpha}} notata), est [[quantitas constans|constans]] [[physica]] primaria quae fortitudinem [[electromagnetismus|interactionis electromagneticae]] inter [[particula elementaris|particulas elementares]] statuit.

Quantitas est {{Creanda|en|Dimensionless quantity|d|Q126818|quantitas sine dimensionibus|numerus simplex sine dimensionibus}} – ergo e nullo peculiari [[systema unitatum mensurae|systemate mensurae]] dependet – et secundum formulam {{math|4{{mvar/pi}}{{mvar/epsilon_0}}{{mvar/hbar}}{{mvar/c}}{{mvar/phyalpha}} {{=}} {{mvar/phye}}<sup>2</sup>}} ad copulationem [[electron]]is et [[campus electricus|campi electrici]] attinet. Nomen ''constantis Sommerfeldianae'' in honorem [[physicus|physici]] [[Germania|Theodisci]] {{Creanda|en|Arnold Sommerfeld|Arnoldus Sommerfeld|Arnoldi Sommerfeld}} ([[1868]]–[[1951]]) electum est, qui anno [[1916]] quantitatem proposuit ad {{Creanda|en|Bohr model|d|Q172948|regula Bohriana atomi|regulam Bohrianam atomi}} augendam. Numerus {{mvar/phyalpha}} quidem hiatum in {{Creanda|en|Fine structure|d|Q1402041|structura subtilis|structura subtili}} {{Creanda|en|Spectral line|d|Q212111|linea spectralis|linearum spectralium}} [[atomus|atomi]] [[hydrogenium|hydrogenii]], quem [[Albertus Abraham Michelson|Albertus A. Michelson]] et {{Creanda|en|Edward W. Morley|d|Q320889|Eduardus Gulielmus Morley|Eduardus G. Morley}} anno [[1887]] praecise mensi erant, definit.

Quantitati constanti circa una centensima tricensima septima pars congruit, vel {{math|0.0072973525693 ≃ {{vfrac|137.035999084}}}} (incertitudine fere {{abbr|1.5 × 10<sup>−10</sup>|“Trium viginti milliardesimarum partium”}}).<ref name="codata-alpha">{{cite web
	| last1 = Mohr
	| first1 = P. J.
	| last2 = Taylor
	| first2 = B. N.
	| last3 = Newell
	| first3 = D. B.
	| year = [[2019]]
	| title = Fine-structure constant
	| work = CODATA Internationally recommended 2018 values of the fundamental physical constants
	| publisher = [[National Institute of Standards and Technology]]
	| url = https://physics.nist.gov/cgi-bin/cuu/Value?alph
}}</ref> Physici nesciunt cur numerus sit talis et non alius,<ref name="feynman-1985">{{cite book
	| last = Feynman
	| first = R.
	| author-link = Ricardus Feynman
	| year = [[1985]]
	| title = QED: The Strange Theory of Light and Matter
	| publisher = [[Princeton University Press]]
	| isbn = 978-0-691-08388-9
	| title-link = QED: The Strange Theory of Light and Matter
	| url = https://archive.org/details/qedstrangetheory00feyn_822/page/n133
	| page = 129
 }}</ref> sed plures modos noscunt ut eius valorem metiantur.

== Definitio ==
Per alias constantes primarias definita, sic {{mvar/phyalpha}} scribi potest:

<math display="block">\alpha = \frac{e^2}{2 \varepsilon_0 h c} = \frac{e^2}{4 \pi \varepsilon_0 \hbar c}</math>

ubi

* {{mvar/phye}} est [[onus electricum]] elementare ({{*ie}} onus [[proton]]is vel [[electron]]is)
* {{mvar/Planck}} est [[constans Planckiana]]
* {{mvar/hbar}} est [[constans Planckiana minuta]], {{*ie}} {{math|{{mvar/hbar}} {{=}} {{vfrac|{{mvar/Planck}}|2{{mvar/pi}}}}}}
* {{mvar/c}} est [[celeritas lucis]]
* {{mvar/epsilon_0}} est [[constans electrica]]

Post {{Creanda|en|2019 redefinition of the SI base units|d|Q3076763|reformatio unitatum primariarum Systematis Internationalis Unitatum anni 2019|reformationem unitatum primariarum systematis metrici anni 2019}}, sola quantitas hic numerata quae definitione exacta caret ({{*ie}} per experimenta metienda est) est constans electrica ({{mvar/epsilon_0}}).

== Notae ==
<references />

{{NexInt}}
* [[Constans Planckiana]]
* [[Mechanica quantica]]
* [[Systema internationale unitatum]]

[[Categoria:Notiones in physica]]
[[Categoria:Physica]]
[[Categoria:Quantitates constantes physicae]]