5.3. Modified Newtonian Dynamics

Modified Newtonian dynamics (MOND, Milgrom 1983a, b), which alters Newton's second law at low accelerations by introducing a multiplicative acceleration constant of 1.2 . 10^-8 cm s^-1, results in M/L ratios that do not require the presence of dark matter. While many attempts have been made to disprove MOND (e.g., Gerhard & Spergel 1992b), none of the presently existing measurements has been able to unambiguously refute MOND for either disk galaxies (van den Bosch & Dalcanton 2000) or dwarfs (e.g, Milgrom 1994; 1995; Côté et al. 1999). MOND remains a possible alternative to dark matter.