fine-structure constant
E590229
The fine-structure constant is a fundamental dimensionless constant of nature that characterizes the strength of the electromagnetic interaction between charged particles.
All labels observed (1)
| Label | Occurrences |
|---|---|
| fine-structure constant canonical | 3 |
Statements (49)
| Predicate | Object |
|---|---|
| instanceOf |
dimensionless physical constant
ⓘ
electromagnetic coupling constant ⓘ fundamental constant of nature ⓘ |
| alsoKnownAs | Sommerfeld constant NERFINISHED ⓘ |
| appearsIn |
Breit interaction
NERFINISHED
ⓘ
Compton scattering formulas NERFINISHED ⓘ Dirac equation solutions for hydrogen ⓘ Thomson scattering cross section ⓘ atomic energy level splittings ⓘ atomic physics ⓘ quantum electrodynamics ⓘ quantum field theory ⓘ scattering cross sections ⓘ |
| approximateValue |
0.00729735257
ⓘ
1/137 ⓘ |
| category |
electromagnetism
ⓘ
fundamental physical constants ⓘ quantum electrodynamics ⓘ |
| characterizes | strength of electromagnetic interaction ⓘ |
| CODATA2018Uncertainty | 0.0000000000011 ⓘ |
| CODATA2018Value | 0.0072973525693 ⓘ |
| definedAs |
e²/(4πϵ₀ħc)
ⓘ
μ₀c e²/(2h) ⓘ |
| dependsOn |
Planck constant
NERFINISHED
ⓘ
elementary charge ⓘ reduced Planck constant ⓘ speed of light in vacuum ⓘ vacuum permeability ⓘ vacuum permittivity ⓘ |
| dimension | dimensionless ⓘ |
| governs | fine structure of atomic spectra ⓘ |
| introducedInContextOf | Bohr–Sommerfeld model of the atom NERFINISHED ⓘ |
| isApproximately | 1/137.035999084 ⓘ |
| isDimensionless | true ⓘ |
| isPositive | true ⓘ |
| isScaleIndependentInQED | approximately true at low energies ⓘ |
| isUniversal | true ⓘ |
| namedAfter | Arnold Sommerfeld NERFINISHED ⓘ |
| numericalValue | 0.0072973525693 ⓘ |
| relatedTo |
electromagnetic interaction
ⓘ
elementary charge ⓘ quantum of action ⓘ |
| roleIn |
Lamb shift
ⓘ
Rydberg constant expressions ⓘ anomalous magnetic moment of the electron ⓘ precision tests of quantum electrodynamics ⓘ |
| symbol | α ⓘ |
| usedFor |
determining other fundamental constants
ⓘ
testing Standard Model of particle physics ⓘ |
Referenced by (3)
Full triples — surface form annotated when it differs from this entity's canonical label.
subject surface form:
ħ