scholarly journals How can rainbow gravity affect gravitational force?

2016 ◽  
Vol 25 (14) ◽  
pp. 1650101 ◽  
Author(s):  
Akram Sadat Sefiedgar
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Force ◽  
Entropic Force ◽  
Recent Proposal ◽  
Modified Newtonian Dynamics ◽  
Corrected Entropy ◽  
Newtonian Dynamics ◽  
Area Law ◽  
Einstein’S General Relativity

According to Verlinde’s recent proposal, the gravity is originally an entropic force. In this paper, we obtain the corrections to the entropy-area law of black holes within rainbow gravity. The corrected entropy-area law leads to the modifications of the number of bits [Formula: see text]. Inspired by Verlinde’s argument on the entropic force, and using the modified number of bits, we can investigate the effects of rainbow gravity on the modified Newtonian dynamics, Newton’s law of gravitation, and Einstein’s general relativity in entropic force approach.

scholarly journals The question on the existence of black holes

2021 ◽  
Vol 34 (4) ◽  
pp. 464-469
Author(s):  
C. Y. Lo
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Force ◽  
Dimensional Space ◽  
Dimensional Theory ◽  
The Earth ◽  
Light Rays ◽  
Necessary Existence ◽  
Bending Of Light ◽  
Einstein’S General Relativity

Simulation shows that general relativity would lead to the existence of black holes if gravitation is always attractive. However, although we observed an invisible and extremely heavy object governs the orbits of stars at the center of our galaxy, we still cannot determine the existence of a black hole. Thus, one may ask whether black holes actually exist. Einstein’s general relativity has been established, because its prediction on the bending of light rays has been confirmed by observation. However, Einstein’s prediction on the increment of weight for a piece of metal as the temperature increases is proven incorrect by experiments, which actually show a reduction of weight. This leads to the necessary existence of repulsive gravitational force, which has been demonstrated by a charged capacitor hovering above the earth. Thus, Einstein, Newton, Galileo, and Maxwell all made the error of overlooking the repulsive gravitational charge-mass interaction. Thus, it is necessary to rejustify the existence of black holes, because gravity is not always attractive. Moreover, repulsive gravitational force makes it necessary to extend general relativity to a five-dimensional theory. Thus, to find out whether black holes exist, it is necessary to investigate the repulsive gravitation and a five-dimensional space.

scholarly journals Alternatives to Dark Matter (?)

2004 ◽  
Vol 220 ◽  
pp. 17-26 ◽  
Author(s):  
Anthony Aguirre
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
General Idea ◽  
Galactic Dynamics ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Visible Matter

It has long been known that Newtonian dynamics applied to the visible matter in galaxies and clusters does not correctly describe the dynamics of those systems. While this is generally taken as evidence for dark matter it is in principle possible that instead Newtonian dynamics (and with it General Relativity) breaks down in these systems. Indeed there have been a number of proposals as to how standard gravitational dynamics might be modified so as to correctly explain galactic dynamics without dark matter. I will review this general idea (but focus on “MOdified Newtonian Dynamics”, or “MOND”), and discuss a number of ways alternatives to dark matter can be tested and, in many cases, ruled out.

scholarly journals ENTROPIC GRAVITY, MINIMUM TEMPERATURE, AND MODIFIED NEWTONIAN DYNAMICS

2011 ◽  
Vol 26 (37) ◽  
pp. 2783-2791 ◽  
Author(s):  
F. R. KLINKHAMER ◽  
M. KOPP
Keyword(s):  
Minimum Temperature ◽  
Degrees Of Freedom ◽  
Gravitational Force ◽  
Wave Length ◽  
Gravitational Acceleration ◽  
De Sitter ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Entropic Gravity ◽  
Holographic Screen

Verlinde's heuristic argument for the interpretation of the standard Newtonian gravitational force as an entropic force is generalized by the introduction of a minimum temperature (or maximum wave length) for the microscopic degrees of freedom on the holographic screen. With the simplest possible setup, the resulting gravitational acceleration felt by a test mass m from a point mass M at a distance R is found to be of the form of the modified Newtonian dynamics (MOND) as suggested by Milgrom. The corresponding MOND-type acceleration constant is proportional to the minimum temperature, which can be interpreted as the Unruh temperature of an emerging de Sitter space. This provides a possible explanation of the connection between local MOND-type two-body systems and cosmology.

Black Hole Massive Thermodynamics

2018 ◽  
Author(s):  
Arbab Arbab
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Gravitational Force ◽  
Quantum Fluctuation ◽  
Photon Radiation ◽  
Photon Mass ◽  
Black Hole Mass ◽  
Speed Of Light ◽  
Curvature Force ◽  
Einstein’S General Relativity

A photon inside a gravitational eld dened by the accelerates g is found to have a gravitational mass given by mg = (ћ=2c3)g, where ћ is the reduced Planck's constant, and c is the speed of light in vacuum. This force is equivalent to the curvature force introduced by Einstein's general relativity. These photons behave like the radiation emitted by a black hole. A black hole emitting such a radiation develops an entropy that is found to increase linearly with black hole mass, and inversely with the photon mass. Based on this, the entropy of a solar black hole emitting photons of mass ~10-33eV amounts to ~1077 kB. The created photons could be seen as resulting from quantum fluctuation during an uncertainty time given by Δt = c/g. The gravitational force on the photon is that of an entropic nature, and varies inversely with the square of the entropy. The power of the massive photon radiation is found to be analogous to Larmor power of an accelerating charge.

scholarly journals Quantum Black Holes in the Sky

Universe ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. 43 ◽  
Author(s):  
Jahed Abedi ◽  
Niayesh Afshordi ◽  
Naritaka Oshita ◽  
Qingwen Wang
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Review Article ◽  
Compact Objects ◽  
Theoretical Underpinning ◽  
The Past ◽  
Einstein’S General Relativity

Black Holes are possibly the most enigmatic objects in our universe. From their detection in gravitational waves upon their mergers, to their snapshot eating at the centres of galaxies, black hole astrophysics has undergone an observational renaissance in the past four years. Nevertheless, they remain active playgrounds for strong gravity and quantum effects, where novel aspects of the elusive theory of quantum gravity may be hard at work. In this review article, we provide an overview of the strong motivations for why “Quantum Black Holes” may be radically different from their classical counterparts in Einstein’s General Relativity. We then discuss the observational signatures of quantum black holes, focusing on gravitational wave echoes as smoking guns for quantum horizons (or exotic compact objects), which have led to significant recent excitement and activity. We review the theoretical underpinning of gravitational wave echoes and critically examine the seemingly contradictory observational claims regarding their (non-)existence. Finally, we discuss the future theoretical and observational landscape for unraveling the “Quantum Black Holes in the Sky”.

scholarly journals Modified Newtonian Dynamics as an Entropic Force

2015 ◽  
Vol 06 (06) ◽  
pp. 786-793 ◽  
Author(s):  
Diego A. Carranza ◽  
Sergio Mendoza
Keyword(s):  
Entropic Force ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics

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 Quantum, noncommutative and MOND corrections to the entropic law of gravitation

2019 ◽  
Vol 33 (05) ◽  
pp. 1950018 ◽  
Author(s):  
Bijan Bagchi ◽  
Andreas Fring
Keyword(s):  
Correction Term ◽  
General Setting ◽  
Minimal Length ◽  
Analytic Method ◽  
Entropic Force ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Classical Setting ◽  
Free Parameters ◽  
Heisenberg's Uncertainty Principle

Quantum and noncommutative corrections to the Newtonian law of inertia are considered in the general setting of Verlinde’s entropic force postulate. We demonstrate that the form for the modified Newtonian dynamics (MOND) emerges in a classical setting by seeking appropriate corrections in the entropy. We estimate the correction term by using concrete coherent states in the standard and generalized versions of Heisenberg’s uncertainty principle. Using Jackiw’s direct and analytic method, we compute the explicit wavefunctions for these states, producing minimal length as well as minimal products. Subsequently, we derive a further selection criterium restricting the free parameters in the model in providing a canonical formulation of the quantum corrected Newtonian law by setting up the Lagrangian and Hamiltonian for the system.

scholarly journals On the Entanglement Entropy of Spacetime and Matter Based on the Action in General Relativity

2019 ◽  
Author(s):  
Hongwei Xiong ◽  
Shujuan Liu
Keyword(s):  
General Relativity ◽  
Gravitational Force ◽  
Entanglement Entropy ◽  
Fundamental Property ◽  
Action Principle ◽  
Classical Particles ◽  
The Relationship ◽  
Einstein’S General Relativity

We consider the conjecture of the relationship between the entanglement entropy of spacetime, matter and the action in Einstein's general relativity. Our analysis suggests the possibility of regarding the entanglement entropy of spacetime and matter as the dimensionless action in general relativity by using Planck units. In this case, the action principle originates from the maximization of the entanglement entropy. We also show that the fundamental property of entanglement entropy leads to attractive characteristic of gravitational force for classical particles.

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