MOND vs. dark matter in light of historical parallels

Abstract

MOND is a paradigm that contends to account for the mass discrepancies in the Universe without invoking `dark' components, such as `dark matter' and `dark energy'. It does so by supplanting Newtonian dynamics and General Relativity, departing from them at very low accelerations. Having in mind readers who are historians and philosophers of science, as well as physicists and astronomers, I describe in this review the main aspects of MOND -- its statement, its basic tenets, its main predictions, and the tests of these predictions -- contrasting it with the dark-matter paradigm. I then discuss possible wider ramifications of MOND, for example the potential significance of the MOND constant, $a_0$, with possible implications for the roots of MOND in cosmology. Along the way I point to parallels with several historical instances of nascent paradigms. In particular, with the emergence of the Copernican world picture, that of quantum physics, and that of relativity, as regards their initial advent, their development, their schematic structure, and their ramifications. For example, the interplay between theories and their corollary laws, and the centrality of a new constant with converging values as deduced from seemingly unrelated manifestations of these laws. I demonstrate how MOND has already unearthed a number of unsuspected laws of galactic dynamics (to which, indeed, $a_0$ is central) predicting them a priori, and leading to their subsequent verification. I parallel the struggle of the new with the old paradigms, and the appearance of hybrid paradigms at such times of struggle. I also try to identify in the history of those established paradigms a stage that can be likened to that of MOND today.

29 pages, 19 figures, Based on a talk at the conference `Dark Matter & Modified Gravity', Aachen, February 2019 Added a discussion of gravitational waves. Added references

References in corpus (40)

• A direct empirical proof of the existence of dark matter
• Dark Matter Candidates from Particle Physics and Methods of Detection
• The Radial Acceleration Relation in Rotationally Supported Galaxies
• A dominant population of optically invisible massive galaxies in the early Universe
• Bimetric MOND gravity
• A Novel Test of the Modified Newtonian Dynamics with Gas Rich Galaxies
• Galaxies as simple dynamical systems: observational data disfavor dark matter and stochastic star formation
• The Tensor-Vector-Scalar theory and its cosmology
• THINGS about MOND
• MOND theory
• A Tale of Two Paradigms: the Mutual Incommensurability of LCDM and MOND
• The Relation between Stellar and Dynamical Surface Densities in the Central Regions of Disk Galaxies
• Dwarf Spheroidals in MOND
• Cosmology and Convention
• Λ CDM is Consistent with SPARC Radial Acceleration Relation
• Andromeda Dwarfs in Light of MOND
• The high mass end of the Tully-Fisher relation
• Galactic rotation curves, the baryon-to-dark-halo-mass relation and space-time scale invariance
• Dynamical friction in modified Newtonian dynamics
• Universal MOND relation between the baryonic and `dynamical' central surface densities of disc galaxies
• Testing MOND Over a Wide Acceleration Range in X-Ray Ellipticals
• A new formulation of the external field effect in MOND and numerical simulations of ultra-diffuse dwarf galaxies $-$ application to NGC 1052-DF2 and NGC 1052-DF4
• Evolution of spiral galaxies in modified gravity: II- Gas dynamics
• Marriage à-la-MOND: Baryonic dark matter in galaxy clusters and the cooling flow puzzle
• The Third Law of Galactic Rotation
• The Extremely High Dark Matter Halo Concentration of the Relic Compact Elliptical Galaxy Mrk 1216
• Dipolar Particles in General Relativity
• Noncovariance at low accelerations as a route to MOND
• The candidate cluster and protocluster catalog (CCPC) II: Spectroscopically identified structures spanning 2 < z < 6.6
• Debye entropic force and modified Newtonian dynamics
• The holographic screen at low temperatures
• MOND and the dark baryons
• Study of gravitational fields and globular cluster systems of early-type galaxies
• Directly testing gravity with Proxima Centauri
• Halo Acceleration Relation
• An Uneven Vacuum Energy Fluid as $\Lambda$, Dark Matter, MOND and Lens
• Dark Energy, Paradigm Shifts, and the Role of Evidence
• Imprint of the galactic acceleration scale on globular cluster systems
• Milgrom Relation Models for Spiral Galaxies from Two-Dimensional Velocity Maps
• Globular Clusters as a Test for Gravity in the Weak Acceleration Regime

Cited by in corpus (31)

• From galactic bars to the Hubble tension: weighing up the astrophysical evidence for Milgromian gravity
• The KBC void and Hubble tension contradict $\Lambda$CDM on a Gpc scale $-$ Milgromian dynamics as a possible solution
• Models of modified-inertia formulation of MOND
• Tripotential MOND theories
• Generalizations of Quasilinear MOND (QUMOND)
• Detecting the Figure Rotation of Dark Matter Halos with Tidal Streams
• Boltzmann hierarchies for self-interacting warm dark matter scenarios
• Deep-MOND polytropes
• Visions in Quantum Gravity
• Non-Newtonian mathematics instead of non-Newtonian physics: Dark matter and dark energy from a mismatch of arithmetics
• Mass-Velocity Dispersion Relation in MaNGA Brightest Cluster Galaxies
• MOND fiducial specific angular momentum of disc galaxies
• Emergent gravity fails to explain color-dependent galaxy-galaxy lensing signals from SDSS Dr7
• What if the universe expands linearly? A local general relativity to solve the "zero active mass" problem
• Dark matter as a gravitational effect in the embedding theory approach
• Central-surface-densities correlation in general MOND theories
• Broader view of bimetric MOND
• Self-Interacting Dark Matter in Cosmology: accurate numerical implementation and observational constraints
• Testing CCC+TL Cosmology with Galaxy Rotation Curves
• Why did the dark matter hypothesis supersede modified gravity in the 1980s?
• Weyl-Invariant Gravity and the Nature of Dark Matter
• Solar System, Astrophysics, and Cosmology from the Derivative Expansion
• Is MOND necessarily nonlinear?
• The $\kappa$-model under test of the SPARC database
• Comparison of HMG and flat rotation velocities inferred from galaxy-galaxy weak lensing
• Universal Basic Mass Density inside Dark Matter Halos
• Modified Newtonian dynamics and hadronic scales
• Examining Baryonic Faber-Jackson Relation in Galaxy Groups
• Hydrostatic equilibrium of X-ray gas in X-COP clusters with HMG
• Bimetric MOND as a framework for variable-$G$ theories -- local systems and cosmology
• Analysis of the equations of motion of fictitious matter in embedding theory