Neither the astrophysicists who say that there is evidence of MOND in wide binaries, nor those who say there is not, are relenting, and I currently rate the debate as inconclusive.
If this paper is right, it is bad for MOND, but good for Deur, who reproduces MOND behavior in galaxies by another formula and mechanism.
Wide binaries (WBs) offer a unique opportunity to test gravity in the low-acceleration regime, where modifications such as Milgromian dynamics (MOND) predict measurable deviations from Newtonian gravity.
We construct a rigorous framework for conducting the wide binary test (WBT), emphasizing high quality sample selection, filtering of poor astrometric solutions, contamination mitigation, and uncertainty propagation. We show that undetected close binaries, chance alignments, and improper treatment of projection effects can mimic MOND-like signals. We introduce a checklist of best practices to identify and avoid these pitfalls. Applying this framework to Gaia DR3 data, we compile a high-purity sample of WBs within 130 pc with projected separations of 1 - 30 kAU, spanning the transition between the Newtonian and MOND regimes.
We find that the scaled relative velocity distribution of wide binaries does not exhibit the 20% enhancement expected from MOND and is consistent with Newtonian gravity across all separations. A meta-analysis of previous WBTs shows that apparent MOND signals diminish as methodological rigour improves. We conclude that when stringent quality controls are applied, there is no observational evidence for MOND-induced velocity boosts in wide binaries.
Our results place strong empirical constraints on modified gravity theories operating between a0/10 and 200 a0, where a0 is the MOND acceleration scale. Across this range of internal accelerations, Newtonian gravity is up to 1500x more likely than MOND for our cleanest sample.
Stephen A. Cookson, Indranil Banik, Kareem El-Badry, Will Sutherland, Zephyr Penoyre, Charalambos Pittordis, Cathie J. Clarke, "A Quality Framework for Testing Gravity with Wide Binaries: No Evidence for MOND" arXiv:2602.24035 (February 27, 2026) (published in MNRAS).
3 comments:
Link back to the latest paper by the other side.
https://dispatchesfromturtleisland.blogspot.com/2026/01/gravity-anomalies-seen-in-wide-binary.html
Indeed.
In that thread, I link to where Stacy McGaugh made his own judgment about who was right. At the time he picked Hernandez, who like Chae claimed evidence for MOND, but more cautiously and with a cleaner sample. Now Chae and Hernandez are on the same team. Meanwhile Banik is also still insisting no MOND... I think that the principles McGaugh uses in his original post, should still be applicable. If you drill down into the details, there is a common set of observational facts, and all these papers pick a subset of those facts and then analyze them using distinct criteria.
Do you have any thoughts (from a legal perspective) on the epistemology of resolving such a situation, where contradictory claims are derived from the same overall body of evidence?
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