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Title: Do wide binary stars show a MOND-like boost in orbital velocity?
Plain: Pairs of stars orbiting each other thousands of times farther apart than the Earth and Sun feel very weak mutual gravity. If MOND is right, they should move noticeably faster than Newton predicts.
Precise: For Gaia wide binaries with internal Newtonian accelerations $g_N$ below $\sim 1e-8\ \mathrm{cm}/\mathrm{s}^2$ (projected separations above about 5000 to 7000 AU for solar-mass pairs), measure $\gamma = G_{\mathrm{eff}} / G$ from the distribution of relative velocities, accounting for hidden triple companions, projection and eccentricities. MOND with the Milky Way external field effect predicts $\gamma \sim 1.4$; Newtonian gravity predicts $\gamma = 1$. An answer is $\gamma$ with uncertainty below 0.05.
Settled by: A wide-binary sample with full 3D relative velocities and spectroscopic exclusion of hidden companions, analyzed with a pre-registered pipeline.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: contested
Status note: Chae (2023) reported a MOND-like boost, Banik et al. (2024) found Newton preferred at $16\sigma$, and Chae et al. (2026) reported $\gamma = 1.60 (+0.24, -0.14)$ from 36 binaries with 3D velocities, above both Newton and standard MOND predictions.
Posed since: (empty)