The Pros And Cons Of MOND

In my view, this analysis is too critical and misses key achievements of MOND-derived theories in the cosmology realm (while doing to little to compare MOND to the competition). But it is still a notable article.

Modified Newtonian Dynamics (MOND) is an alternative to the dark matter hypothesis that attempts to explain the "missing gravity" problem in astrophysics and cosmology through a modification to objects' dynamics. Since its conception in 1983, MOND has had a chequered history. Some phenomena difficult to understand in standard cosmology MOND explains remarkably well, most notably galaxies' radial dynamics encapsulated in the Radial Acceleration Relation. But for others it falls flat -- mass discrepancies in clusters are not fully accounted for, the Solar System imposes a constraint on the shape of the MOND modification seemingly incompatible with that from galaxies, and non-radial motions are poorly predicted. An experiment that promised to be decisive -- the wide binary test -- has produced mainly confusion. This article summarises the good, the bad and the ugly of MOND's observational existence. I argue that despite its imperfections it does possess ongoing relevance: there may yet be crucial insight to be gleaned from it.

Harry Desmond, "Modified Newtonian Dynamics: Observational Successes and Failures" arXiv:2505.21638 (May 27, 2025) (8 pages) (invited contribution to the 2025 Gravitation session of the 59th Rencontres de Moriond).