Fine-Structure Constant definition of Fine-Structure Constant in the Free Online Encyclopedia.

fine-structure constant [′fīn ‚strək·chər ′kän·stənt]

(physics)

A fundamental dimensionless constant, equal toe²/(4πε₀ℏc) in International System (SI) units and toe²/(ℏc) in centimeter-gram-second (cgs) electrostatic units, whereeis the elementary charge, ℏ is Planck's constant divided by 2π,cis the speed of light, and ε₀is the electric constant; numerically, it is equal to 0.007 297 352 533 ± 0.000 000 000 027 or to 1/(137.035 999 76 ± 0.000 000 50); symbolized α. Also known as Sommerfeld fine-structure constant.

Fine-Structure Constant

(α), a dimensionless quantity formed from universal physical constants: α = e²/hc ≠ 1/137, where e is the elementary electric charge, h is Planck’s constant, and c is the speed of light in a vacuum. According to the most accurate measurements, which are based on the Josephson effect, α^–1 = 137.0359 ± 0.0004. The constant α is called the fine-structure constant because it determines the fine structure of the energy levels of an atom in the sense that the magnitude of the fine-structure splitting is proportional to α². In quantum electrodynamics, α is a natural parameter that characterizes the strength of the electromagnetic interaction.

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No references found	In recent years, astrophysical data have indicated that the fine-structure constant called alpha has increased since the early universe. Terrific timekeeper: optical atomic clock beats world standard by Weiss, P. / Science News Pepper, New Method for High-Accuracy Determination of the Fine-Structure Constant Based on Quantized Hall Resistance, Phys. Temperature dependence of the Hall and longitudinal resistances in a ... by Cage, M.E. / Journal of Research of the National Institute of Standards and Technology Since 2001, Flambaum and his colleagues have presented growing evidence that another constant, known as alpha or the fine-structure constant, has also varied (SN: 10/6/01, p. Universe in Flux: constant of nature might have changed by Weiss, P. / Science News	fine delay fine earth Fine Gael fine gold fine grading fine grain fine gravel fine grinding fine index fine mineral surfacing fine sand fine sawn fine silver Fine Structure fine stuff Fine, Henry Burchard Fine, Irving Fine, Vivian Fine-Aggregate Concrete fine-drawn fine-grain fine-grained fine-grown fine-line printer fine-screen halftone Fine-Structure Constant fine-textured Fine-Wooled Sheep Raising fineblanking Finelli, Giuliano fineness fineness modulus fineness of grind Fineness of Precious Metals fineness ratio finer finery finery process Fines Fines, Indisputable finesse finfoot finfooted mammal Fingal Fingal's Cave finger finger bit finger board finger chute finger coal finger gripper	fine-line printer fine-looking fine-mannered Fine-mapping fine-mesh Fine-Mesh Screen Fine-needle aspiration Fine-needle aspiration fine-needle aspiration biopsy fine-needle aspiration biopsy fine-needle aspiration biopsy Fine-Needle Aspiration Cytology Fine-Needle Aspiration of the Thyroid Fine-Needle Aspiration Puncture Fine-Needle Aspiration Specimens Fine-Needle Capillary Biopsy Fine-Needle Thyroid Aspiration Fine-Needle Transthoracic Aspiration Fine-needle-Catheter Jejunostomy Fine-Pitch Ball Grid Array Fine-Pitch Grid Array Fine-Pitch Quad Flat Pack Fine-Pitched High Density Buildup Fine-print Fine-print Fine-Scale Genetic Structure fine-screen halftone fine-spun Fine-Structure Constant fine-structure constants fine-textured fine-textured Fine-Thank You fine-tooth fine-tooth comb fine-tooth combs fine-toothed fine-toothed comb fine-toothed combs fine-tune fine-tune fine-tuned fine-tuned fine-tunes fine-tunes fine-tuning fine-tuning fine-wool Fine-Wooled Sheep Raising Fine/Very Fine fineable fineable fineable fineable fineblanking FINEC Finecorsa fined fined

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In recent years, astrophysical data have indicated that the fine-structure constant called alpha has increased since the early universe.

Terrific timekeeper: optical atomic clock beats world standard by Weiss, P. / Science News

Pepper, New Method for High-Accuracy Determination of the Fine-Structure Constant Based on Quantized Hall Resistance, Phys.

Temperature dependence of the Hall and longitudinal resistances in a ... by Cage, M.E. / Journal of Research of the National Institute of Standards and Technology

Since 2001, Flambaum and his colleagues have presented growing evidence that another constant, known as alpha or the fine-structure constant, has also varied (SN: 10/6/01, p.

Universe in Flux: constant of nature might have changed by Weiss, P. / Science News

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