Perex
Milgromian dynamics (MOND) is an alternative to non-baryonic cold dark matter, proposed by Moti Milgrom in 1983. In this talk, I will review the successes and challenges that the MOND paradigm faces on the scales of galaxies, galaxy groups, and galaxy clusters. Firstly, I will focus on the dynamical regularities and empirical laws shown by galaxies, which point to the existence of a characteristic acceleration scale. These observational facts that were predicted a-priori by MOND. Next, I will illustrate the problem of galaxy clusters in MOND and discuss possible solutions to this long-standing challenge.