The modified Newtonian dynamics—MOND and its implications for new physics

Abstract

No more salient issue exists in contemporary astrophysics and cosmology than that of the elusive "dark matter". For many years already Milgrom's paradigm of modified Newtonian dynamics (MOND) has provided an alternative way to interpret observations without appeal to invisible dark matter. MOND had been successful in elucidating economically the dynamics of disk galaxies of all scales, while doing less well for clusters of galaxies; in its original form it could not address gravitational lensing or cosmology. After reviewing some of the evidence in favor of MOND, I recollect the development of relativistic formulations for it to cope with the last deficiency. I comment on recent work by various groups in confronting TeVeS, a relativistic embodiment of MOND, with observational data on gravitational lensing and cosmology. Throughout I ask what sort of physics can be responsible for the efficacy of MOND, and conclude with an appraisal of what theoretical developments are still needed to reach a full description of the world involving no unobserved matter.

Understanding local dwarf spheroidals and their scaling relations under MOdified Newtonian Dynamics

“…On the other hand, some researchers (see e.g. Bekenstein 2006 and references therein) claim that the Pioneer anomaly can be explained by the MOND hypothesis. This assumption can prove wrong if uneven thermal radiation in the spacecrafts is found (Toth & Turyshev 2009), which could possibly come from the flyby anomaly (Turyshev 2009).…”

Causality and the speed of sound

“…Low-energy effective field theories have been rejected when, despite having Lorentz-invariant Lagrangians, they admit superluminal fluctuations [5]. Subluminal propagation of field fluctuations has been imposed as a condition on a relativistic gravitation theory for the MOND paradigm [6,7].…”

Constraints on non-Newtonian gravity and light elementary particles from measurements of the Casimir force by means of a dynamic atomic force microscope

“…The modified Newtonian dynamics is discussed [6] as an alternative to the proposed existence of dark matter which should comprise about 23% of the Universe mass. On the other hand, if it is granted that the most realistic according to astrophysics, cold, dark matter exists in nature, the question arises as to what are its constituents.…”

“…Equations (4) and (5) were substituted in inequality (6). It was shown that the strongest constraints follow at the shortest separation a = 235 nm.…”