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ZENODO
Preprint . 2026
License: CC BY
Data sources: ZENODO
ZENODO
Preprint . 2026
License: CC BY
Data sources: Datacite
ZENODO
Preprint . 2026
License: CC BY
Data sources: Datacite
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Solid Angle and the Fine-Structure Constant: Uncovering the Exact Geometric Relationship Between Hydrogen's Physical Scales

Authors: Harari, Zaki;

Solid Angle and the Fine-Structure Constant: Uncovering the Exact Geometric Relationship Between Hydrogen's Physical Scales

Abstract

We show that the ratio of the hydrogen Lyman-limit wavelength λ_Ly to the Bohr radius a₀ satisfies the exact identity λ_Ly/a₀ = 4π/α = Ω_sph/α, where α ≈ 1/137 is the fine-structure constant and Ω_sph = 4π sr is the solid angle of a complete sphere. Using only CODATA 2022 values of the fundamental constants and four lines of algebra, we demonstrate that every factor in this identity carries a transparent physical meaning: α measures the ratio of the electron's ground-state speed to c; the factor 2π encodes one complete oscillation cycle (h = 2πℏ); and the remaining factor of 2 follows from the virial theorem applied to the Coulomb potential, ⟨T⟩ = −E_total, which sets E_R = ½ m_e c² α². These two factors—2π and 2—are structurally identical to the azimuthal and polar integrals whose product yields Ω_sph = 4π sr. We stress that this decomposition is tied to the convention of expressing photon energy through the linear frequency ν via the Planck constant h; in a natural-unit convention based on ℏ the factor 2π does not appear, and the decomposition changes accordingly. The result is verified numerically to better than one part in 10⁸ using CODATA 2022 data. We further present the hierarchy of all three electromagnetic length scales of hydrogen (r_e, a₀, λ_Ly), each separated by specific powers of α and the factor 4π, and we discuss implications for dimensional analysis, atomic units, and extensions to hydrogenic ions and two-photon spectroscopy. The finite proton-mass correction shifts the ratio by +0.054%, in agreement with the measured Lyman limit. No new physics is proposed; the paper illuminates a geometric structure that is exact, experimentally grounded, and largely absent from standard presentations of atomic physics.

Keywords

atomic units, hydrogen atom, hydrogenic ions, dimensional analysis, fine-structure constant, solid angle, Lyman limit, Bohr radius

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
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