The MOND acceleration scale a₀ ≈ 1.2 × 10⁻¹⁰ m/s² is empirically required to fit galaxy rotation curves. We note that this value is numerically close to cH₀/(2π) ≈ 1.08 × 10⁻¹⁰ m/s², within observational uncertainties. Motivated by horizon thermodynamics, we explore the hypothesis that a₀ is not a fundamental constant but rather set by the cosmic horizon. Under this hypothesis, a₀(z) = cH(z)/(2π), predicting that a₀ should scale with the Hubble parameter. This yields an increase by a factor ∼3 at redshift z = 2, testable with JWST rotation curves of high-redshift galaxies. Confirmation would establish a link between galaxy dynamics and cosmic expansion.
Austin Friedrich (2026) studied this question.