The Proton-to-Electron Mass Ratio from Methanol and Ammonia Absorption: Bounds in the Frame
Year: 2026
Type: article
Abstract: The proton-to-electron mass ratio, mu, is probed at cosmological distance by methanol absorption at redshift 0.89, which gives a fractional offset of zero within an uncertainty of 1.00e-07 (Bagdonaite et al. 2013). Spread over the 7.5 billion year lookback, the two-standard-deviation room corresponds to a mean rate of 2.67e-17 per year and a logarithmic-accumulation coupling of 3.14e-07. What that room means for the fine-structure constant depends entirely on the ratio linking the two constants: under a grand-unified-style linkage the methanol result alone would bound alpha's change to 1.03e-08, while under an electromagnetic-only linkage it bounds it at 2.00e-07. The frame's joint predictions are developed from these numbers. Computed from published inputs, not measured.
Author: Aldred, William Alexander
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225834868
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