MOND as the basis for an extended theory of gravity

2015 ◽  
Vol 93 (2) ◽  
pp. 217-231 ◽  
Author(s):  
S. Mendoza
Keyword(s):  
Equivalence Principle ◽  
Clusters Of Galaxies ◽  
Relativistic Theory Of Gravity ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Acceleration Of The Universe ◽  
Theory Of Gravity ◽  
The Universe ◽  
Geometric Nature ◽  
Bending Of Light

This review describes why the geometric nature of space–time, the Einstein equivalence principle, and the geodesic motion of particles show the possibility of building an extended relativistic theory of gravity on regions where the Tully–Fisher law is valid. It is also shown how a metric construction of gravity can have a modified Newtonian dynamics behaviour compatible with the Tully–Fisher law and the bending of light observed in individual, groups, and clusters of galaxies. It is also reviewed how this metric theory of gravity fits reasonably well on cosmological scales explaining the current acceleration of the universe.

scholarly journals DIRECT DETERMINATIONS OF THE REDSHIFT BEHAVIOR OF THE PRESSURE, ENERGY DENSITY, AND EQUATION OF STATE OF THE DARK ENERGY AND THE ACCELERATION OF THE UNIVERSE

2005 ◽  
Vol 20 (06) ◽  
pp. 1113-1120 ◽  
Author(s):  
RUTH A. DALY ◽  
S. G. DJORGOVSKI
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Radio Galaxy ◽  
A Priori ◽  
Acceleration Rate ◽  
Acceleration Of The Universe ◽  
Theory Of Gravity ◽  
The Universe

One of the goals of current cosmological studies is the determination of the expansion and acceleration rates of the universe as functions of redshift, and the determination of the properties of the dark energy that can explain these observations. Here the expansion and acceleration rates are determined directly from the data, without the need for the specification of a theory of gravity, and without adopting an a priori parameterization of the form or redshift evolution of the dark energy. We use the latest set of distances to SN standard candles from Riess et al. (2004), supplemented by data on radio galaxy standard ruler sizes, as described by Daly & Djorgovski (2003, 2004). We find that the universe transitions from acceleration to deceleration at a redshift of zT≈0.4, with the present value of q0=-0.35±0.15. The standard "concordance model" with Ω0=0.3 and Λ=0.7 provides a reasonably good fit to the dimensionless expansion rate as a function of redshift, though it fits the dimensionless acceleration rate as a function of redshift less well. The expansion and acceleration rates are then combined with a theory of gravity to determine the pressure, energy density, and equation of state of the dark energy as functions of redshift. Adopting General Relativity as the correct theory of gravity, the redshift trends for the pressure, energy density, and equation of state of the dark energy out to z~1 are determined, and are found to be generally consistent with the concordance model; they have zero redshift values of p0=-0.6±0.15, f0=0.62±0.05, and w0=-0.9±0.1.

THE HOLOGRAPHIC SCENARIO, THE MODIFIED INERTIA AND THE DYNAMICS OF THE UNIVERSE

2012 ◽  
Vol 27 (34) ◽  
pp. 1250208 ◽  
Author(s):  
JAUME GINÉ
Keyword(s):  
Casimir Effect ◽  
Dynamical Evolution ◽  
High Energy ◽  
Accelerated Expansion ◽  
Late Time ◽  
Holographic Model ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Expansion Of The Universe ◽  
The Universe

This paper attempts to connect two new gravitational mechanisms: the Verlinde's holographic model of gravity and the modification of inertia resulting from a Hubble-scale Casimir effect (MiHsC) of McCulloch. First we give a short survey about how the holographic scenario can give the correct dynamics of the universe. The introduction of a two-holographic screens one comparable to the Hubble horizon and a second screen that takes into account the contribution of all the matter between the test particle and the observer gives directly the modified Friedmann acceleration equation for the dynamical evolution of the universe. Improvements of this equation using the quantum corrections will realize the inflation at high energy scales and the late-time acceleration (i.e. the accelerated expansion of the universe nowadays) obviating the dark energy. From both models we can derive a version of Modified Newtonian Dynamics (MOND) observed in the dynamics of the astronomical objects obviating the dark matter and explaining other astronomical anomalies. A first connection between both theories is given at the end of the paper.

scholarly journals THE FAILURES OF THE STANDARD MODEL OF COSMOLOGY REQUIRE A NEW PARADIGM

2012 ◽  
Vol 21 (14) ◽  
pp. 1230003 ◽  
Author(s):  
PAVEL KROUPA ◽  
MARCEL PAWLOWSKI ◽  
MORDEHAI MILGROM
Keyword(s):  
Standard Model ◽  
Cold Dark Matter ◽  
Universal Constant ◽  
Classical Dynamics ◽  
New Paradigm ◽  
Local Systems ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
The Standard Model ◽  
The Universe

Cosmological models that invoke warm or cold dark matter cannot explain observed regularities in the properties of dwarf galaxies, their highly anisotropic spatial distributions, nor the correlation between observed mass discrepancies and acceleration. These problems with the standard model of cosmology have deep implications, in particular in combination with the observation that the data are excellently described by Modified Newtonian Dynamics (MOND). MOND is a classical dynamics theory which explains the mass discrepancies in galactic systems, and in the universe at large, without invoking 'dark' entities. MOND introduces a new universal constant of nature with the dimensions of acceleration, a0, such that the pre-MONDian dynamics is valid for accelerations a ≫ a0, and the deep MONDian regime is obtained for a ≪ a0, where spacetime scale invariance is invoked. Remaining challenges for MOND are (i) explaining fully the observed mass discrepancies in galaxy clusters, and (ii) the development of a relativistic theory of MOND that will satisfactorily account for cosmology. The universal constant a0 turns out to have an intriguing connection with cosmology: ā0 ≡ 2πa0 ≈ cH0 ≈ c2(Λ/3)1/2. This may point to a deep connection between cosmology and internal dynamics of local systems.

Cosmological principle in Newtonian dynamics

2020 ◽  
Vol 35 (16) ◽  
pp. 2050131 ◽  
Author(s):  
David Benisty ◽  
Eduardo I. Guendelman
Keyword(s):  
Equivalence Principle ◽  
Consistency Condition ◽  
Nonlinear Function ◽  
Newtonian Potential ◽  
Second Law ◽  
Newtonian Gravity ◽  
Cosmological Principle ◽  
The Poisson Equation ◽  
Newtonian Dynamics ◽  
The Universe

A correspondence between the equivalence principle and the homogeneity of the universe is discussed. In Newtonian gravity, translation of co-moving coordinates in a uniformly expanding universe defines an accelerated frame. A consistency condition for the invariance of this transformation which requires a well-defined transformation for the Newtonian potential, yields the Friedmann equations. All these symmetries are lost when we modify Newton’s Second Law (NSL) or the Poisson equation. For example, by replacing NSL with nonlinear function of the acceleration, the concept of relative acceleration is lost and the homogeneity of the universe breaks.

scholarly journals Gravitational Lensing and Modified Newtonian Dynamics

2001 ◽  
Vol 18 (2) ◽  
pp. 189-191
Author(s):  
Daniel J. Mortlock ◽  
Edwin L. Turner
Keyword(s):  
General Relativity ◽  
Gravitational Lensing ◽  
A Priori ◽  
Massive Particle ◽  
Speed Of Light ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Visible Matter ◽  
Relativistic Extension ◽  
The Universe

AbstractGravitational lensing is most often used as a tool to investigate the distribution of (dark) matter in the universe, but, if the mass distribution is known a priori, it becomes, at least in principle, a powerful probe of gravity itself. Lensing observations are a more powerful tool than dynamical measurements because they allow measurements of the gravitational field far away from visible matter. For example, modified Newtonian dynamics (MOND) has no relativistic extension, and so makes no firm lensing predictions, but galaxy–galaxy lensing data can be used to empirically constrain the deflection law of a MONDian point-mass. The implied MONDian lensing formalism is consistent with general relativity, in so far as the deflection experienced by a photon is twice that experienced by a massive particle moving at the speed of light. With the deflection law in place and no invisible matter, MOND can be tested wherever lensing is observed.

scholarly journals Oscillating Cosmological Force Modifies Newtonian Dynamics

Galaxies ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 45
Author(s):  
Igor I. Smolyaninov
Keyword(s):  
Lorentz Invariance ◽  
Planck Scale ◽  
Scale Factor ◽  
Disk Galaxies ◽  
Cosmological Constant Problem ◽  
Quantum Oscillations ◽  
Newtonian Dynamics ◽  
Acceleration Of The Universe ◽  
The Universe ◽  
Central Gravitational Field

In the Newtonian limit of general relativity a force acting on a test mass in a central gravitational field is conventionally defined by the attractive Newtonian gravity (inverse square) term plus a small repulsive cosmological force, which is proportional to the slow acceleration of the universe expansion. In this paper we considered the cosmological-force correction due to fast quantum oscillations of the universe scale factor as a potential solution of the cosmological constant problem. These fast fluctuations of the cosmological scale factor violate Lorentz invariance at the Planck scale, and they induce strong changes to the current sign and magnitude of the average cosmological force, thus making it one of the potential probable causes for the modification of Newtonian dynamics in galaxy-scale systems. The modified cosmological force may be responsible for the recently discovered “cosmic-clock” behavior of disk galaxies in the low-redshift universe. The obtained results have strong implications for astroparticle physics since they demonstrate that typical galaxy rotation curves may be obtained without (or almost without) dark-matter particles.

scholarly journals STEP as a Decisive Test of MOND on Earth

2017 ◽  
Vol 45 ◽  
pp. 1760013
Author(s):  
Jonas P. Pereira
Keyword(s):  
Dark Matter ◽  
Equivalence Principle ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Current Design ◽  
Decisive Test ◽  
Alternative Theories

We review and emphasize the importance of the Satellite Test of the Equivalence Principle (STEP) in probing one of the most successful and popular alternative theories to dark matter known as Modified Newtonian Dynamics (MOND), on Earth. This would be achieved with no modification of STEP’s current design and sensitivity and if MOND exists STEP could in principle easily detect it.

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