A historical perspective on modified Newtonian dynamics

Abstract

I review the history and development of modified Newtonian dynamics (MOND) beginning with the phenomenological basis as it existed in the early 1980s. I consider Milgrom's papers of 1983 introducing the idea and its consequences for galaxies and galaxy groups, as well as the initial reactions, both negative and positive. The early criticisms were primarily on matters of principle, such as the absence of conservation laws and perceived cosmological problems; an important step in addressing these issues was the development of the Lagrangian-based nonrelativistic theory of Bekenstein and Milgrom. This theory led to the development of a tentative relativistic theory that formed the basis for later multifield theories of gravity. On an empirical level the predictive success of the idea with respect to the phenomenology of galaxies presents considerable challenges for cold dark matter. For MOND the essential challenge remains the absence of a generally accepted theoretical underpinning of the idea and, thus, cosmological predictions. I briefly review recent progress in this direction. Finally I discuss the role and sociology of unconventional ideas in astronomy in the presence of a strongly entrenched standard paradigm. PACS Nos.: 01.65.+g, 95.35.+d, 98.62.−g, 98.80.−k.Résumé : Nous passons en revue l'histoire et le développement de la dynamique newtonienne modifiée (MOND), en commençant avec la base phénoménologique, telle qu'elle existait au début des années 1980. Nous étudions la publication de Milgrom en 1983, qui introduit les idées et les conséquences pour les galaxies et les amas de galaxies, avec les réactions initiales, positives et négatives. Les premières critiques portaient sur des points de principe, comme l'absence de lois de conservation et de possibles problèmes cosmologiques. Une étape importante pour répondre à ces questions paraît dans le papier de Bekenstein et Milgrom qui développe une théorie non relativiste basée sur un Lagrangien. Cette théorie mène au développement d'un essai de théorie relativiste qui forme la base pour des théories à venir de gravité à champs multiples. Sur une base empirique, le succès des prédictions concernant la phénoménologie des galaxies présente tout un défi pour la matière noire froide. Pour MOND, la difficulté demeure l'absence d'une base théorique généralement acceptée soutenant ses idées de base et conséquemment les prédictions cosmologiques. Nous revoyons brièvement les récents progrès dans cette direction. Nous discutons finalement du rôle et de la sociologie d'idées non conventionnelles en astronomie en présence de paradigmes fortement ancrés. [Traduit par la Rédaction]

Emergent Gravity and the Dark Universe

“…The observed flattening of rotation curves, as well as many other observations of dark matter phenomena, indicate that they are controlled by the Hubble acceleration scale a 0 , as first pointed out by Milgrom [32]. It is an empirical fact [33][34][35] that the 'missing mass problem', usually interpreted as observational evidence for dark matter, only occurs when the gravitational acceleration falls below a certain critical value that is of the order of a 0 . This criterion can be alternatively formulated in terms of the surface mass density.…”

“…In this case one finds a M = a 0 /6, which is indeed the acceleration scale that appears in Milgrom's phenomenological fitting formula [34,35]. We like to emphasise that these scaling relations are not new laws of gravity or inertia, but appear as estimates of the strength of the extra dark gravitational force.…”

“…The last expression is the generalization of equation (35). Since the entropy is only removed from the region M we can treat the medium as being incompressible outside of M .…”

“…To get the right amount one would need to multiply a M by about a factor of 3 according to [33,35]. Equation (102) also can not account for the observed strong gravitational lensing due to dark matter in the central parts of the cluster, since the projected surface mass densities required for strong lensing are larger than the expected value a M /πG by about factor of 6 [61].…”

Search for Dark Matters at Accelerators

“…However we must keep in mind that this model is not the only one proposed for the interpretations of the nature of dark matter, and that some of these are impossible to be tested at accelerators. One obvious example is the MOdification of the Newtonian Dynamics (MOND) on very large astronomical scales, a well known ad hoc solution of the missing mass problem that was invoked by Milgrom [14], and has stimulated the publications of many thousand of refereed theoretical papers until recent [15]. But, with few exceptions, all types of candidates DM particles, such as for example supersymmetric (SUSY) particles, primordial black holes, MACHO's, sterile neutrinos,axions, etc.…”