Sabine Hossenfelder is offering a new version
of modified Newtonian dynamics, or MOND, which she calls Covariant Emergent
Gravity, or CEG. She explains it at her blog Backreaction here and in an arXiv paper here. She shows that CEG fits the data on the radial acceleration of
stars in galaxies much better than particle dark matter. There’s no doubt that
she’s right. The problem is that there’s ample evidence for the existence of
dark matter, and no known reason why the acceleration of gravity should
suddenly change at some distance from a center of mass.
