Gravitational alternatives to dark matter with tensor mode speed equaling the speed of light

2019 ◽  
Vol 100 (10) ◽  
Author(s):  
Constantinos Skordis ◽  
Tom Złośnik
Keyword(s):  
Dark Matter ◽  
Speed Of Light ◽  
Tensor Mode

scholarly journals Formation of Elements and Compounds in Space in Early Universe

2016 ◽  
Vol 8 (6) ◽  
pp. 86
Author(s):  
Abdul L. Bhuiyan
Keyword(s):  
Dark Matter ◽  
High Temperature ◽  
Early Universe ◽  
High Speed ◽  
Virtual State ◽  
Speed Of Light ◽  
Electron Positron ◽  
Living Organisms ◽  
The Universe

<p class="1Body">At the end of the period of contraction of the universe, all objects transform into gravity particles such as photons and electron- positron pairs which exist in virtual state in spacetime at an extremely high temperature. These particles move with extremely high speed comparable to the speed of light. As the early universe starts cooling, the speed of the particles starts to decrease when photons and electron- positron pairs move out of spacetime and appear as real particles. As the temperature continues to fall due to cooling, the electron- positron pairs start forming quarks (u and d) while simultaneously the energy of photons transform into dark matter. The u quarks and d quarks then continue to form nuclei of different elements including radio elements. Simultaneously, the lighter elements such as hydrogen, nitrogen, carbon, oxygen, phosphorus, etc. form the precursors to DNAs and RNAs of living organisms.</p>

scholarly journals Can a negative-mass cosmology explain dark matter and dark energy?

2019 ◽  
Vol 626 ◽  
pp. A5 ◽  
Author(s):  
H. Socas-Navarro
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Cosmological Model ◽  
Large Scale ◽  
Dark Matter Halos ◽  
Challenging Problem ◽  
Speed Of Light ◽  
Negative Mass ◽  
Galactic Dark Matter

A recent study by Farnes (2018, A&A, 620, A92) proposed an alternative cosmological model in which both dark matter and dark energy are replaced with a single fluid of negative mass. This paper presents a critical review of that model. A number of problems and discrepancies with observations are identified. For instance, the predicted shape and density of galactic dark matter halos are incorrect. Also, halos would need to be less massive than the baryonic component, otherwise they would become gravitationally unstable. Perhaps the most challenging problem in this theory is the presence of a large-scale version of the “runaway effect”, which would result in all galaxies moving in random directions at nearly the speed of light. Other more general issues regarding negative mass in general relativity are discussed, such as the possibility of time-travel paradoxes.

MAXWELL BRANE COSMOLOGY WITH HIGHER-ORDER STRING CURVATURE CORRECTIONS, A NONMINIMALLY COUPLED SCALAR FIELD, DARK MATTER–DARK ENERGY INTERACTION AND A VARYING SPEED OF LIGHT

2009 ◽  
Vol 18 (02) ◽  
pp. 289-318 ◽  
Author(s):  
R. A. EL-NABULSI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Friedmann Equation ◽  
Building Blocks ◽  
Higher Order ◽  
Alternative Theory ◽  
Speed Of Light ◽  
Energy Interaction ◽  
Curvature Term

We investigate the cosmological effects of an alternative theory of gravity on the four-dimensional Randall–Sundrum braneworld of type II with a higher-order string curvature term added to the action. We discuss the possibility of a varying speed of light, which has recently attracted considerable attention, in the presence a Maxwell field and of a dynamically evolving bulk scalar field nonminimally coupled to scalar curvature in a quadratic form, together with a dark matter–dark energy interaction term. After deriving the modified Friedmann equation on the brane, as well as the scalar field equations, we then analyze the dynamical equations obtained so far. Special attention is paid to scaling solutions which could be important building blocks in constructing the models of dark energy. The constructed model exhibits several features of cosmological and astrophysical interest for both the early and the late universe, consistent with recent observations, in particular the ones concerned with celerity of light, four and five gravitational constants, black hole masses and entropies.

scholarly journals Electromagnetic waves propagating in the string axiverse

2018 ◽  
Vol 2018 (4) ◽  
Author(s):  
Daiske Yoshida ◽  
Jiro Soda
Keyword(s):  
Dark Matter ◽  
Electromagnetic Field ◽  
Dispersion Relation ◽  
Resonance Frequency ◽  
Parametric Resonance ◽  
Electromagnetic Waves ◽  
Coupling Constant ◽  
Speed Of Light ◽  
Coherent Oscillation ◽  
Chern Simons

Abstract It is widely believed that axions are ubiquitous in string theory and could be dark matter. The peculiar features of axion dark matter are coherent oscillations and a coupling to the electromagnetic field through the Chern–Simons term. In this letter, we study the consequences of these two features of axions with mass in the range $10^{-13}\,{\rm eV}$ to $10^{3}\,{\rm eV}$. First, we study the parametric resonance of electromagnetic waves induced by the coherent oscillation of the axion. Since the resonance frequency is determined by the mass of the axion dark matter, if we detect this signal, we can get information on the mass of the axion dark matter. Second, we study the velocity of light in the background of the axion dark matter. In the presence of the Chern–Simons term, the dispersion relation is modified and the speed of light will oscillate in time. It turns out that the change in the speed of light would be difficult to observe. We argue that future radio wave observations of the resonance can give rise to a stronger constraint on the coupling constant and/or the density of the axion dark matter.

scholarly journals Idea of multi cohesive areas - foundation, current status and perspective

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 104-127
Author(s):  
Maciej Chojnowski
Keyword(s):  
Experimental Data ◽  
Dark Matter ◽  
Dark Energy ◽  
Theoretical Model ◽  
Theoretical Foundation ◽  
Quantum Particle ◽  
Current Status ◽  
Speed Of Light ◽  
Current Experimental Data ◽  
Matter Sector

Abstract The idea of multi cohesive areas is a new, theoretical model of quantum particle mass. This model contains a dark matter sector. Moreover, it can explain the current experimental data on both dark matter and dark energy phenomena. In this work, the current status of this idea from theoretical and experimental perspective will be shown. It will be done by presenting the motivation behind its creation, its theoretical foundation and how it explains the mentioned current experimental data. The result from this work is a proof that in the further MCA development, quantities like particles or fields have to find a new image in which they are created by the speed of light. The conclusion from this work is that the mentioned development can create a theory for all interactions. Moreover, such a theory will have a practical value. Namely, by using this theory, the “disappearing” matter in the visible world will be available by changing into dark matter. This, together with the fact that the current dark matter models do not yield any significance outcomes, is a proof that such a development is at least worth considering.

scholarly journals Warm dark matter and Hubble constant tensions

2019 ◽  
pp. 46-48 ◽  
Author(s):  
S. Parnovsky
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Energy Density ◽  
Cosmological Model ◽  
Hubble Constant ◽  
Baryonic Matter ◽  
Speed Of Light

The tensions between the values of Hubble constant obtained from the early and the late Universe could be eliminated if we use the ΛWDM cosmological model with dark energy, baryonic matter and warm dark matter (WDM) with characteristic velocities about 16 % of the speed of light. A pressure of WDM is equal to its energy density multiplied by factor 0.009.

scholarly journals Gravitational Waves in Axion Dark Matter

Universe ◽  
2020 ◽  
Vol 6 (7) ◽  
pp. 89 ◽  
Author(s):  
Chong-Sun Chu ◽  
Jiro Soda ◽  
Daiske Yoshida
Keyword(s):  
Dark Matter ◽  
Gravitational Waves ◽  
Parametric Amplification ◽  
Coupling Constant ◽  
Speed Of Light ◽  
Coherent Oscillation ◽  
Axion Field ◽  
Specific Frequency ◽  
Chern Simons

Axion dark matter is interesting as it allows a natural coupling to the gravitational Chern–Simons term. In the presence of an axion background, the gravitational Chern–Simons term produces parity violating effects in the gravitational sector, in particular on the propagation of gravitational waves. Previously, it has been shown that the coherent oscillation of the axion field leads to a parametric amplification of gravitational waves with a specific frequency. In this paper, we focus on the parity violating effects of the Chern–Simons coupling and show the occurrence of gravitational birefringence. We also find deviation from the speed of light of the velocity of the gravitational waves. We give constraints on the axion-Chern–Simons coupling constant and the abundance of axion dark matter from the observation of GW170817 and GRB170817A.

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