796 results on '"Particle horizon"'
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2. Do Physical Laws/Physics Parameter Constants Remain Invariant from a Prior Universe, to the Present Universe?
- Author
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Andrew Beckwith
- Subjects
Physics ,Theoretical physics ,De Sitter universe ,Steady State theory ,Big Rip ,Entropy (arrow of time) ,Flatness problem ,Particle horizon ,Distance measures ,Metric expansion of space - Abstract
The invariance of physical law between a prior to a present universe is brought up, as a continuation of analyzing entropy in today’s universe, and the relationship of entropy to information content in a prior universe. If or not there is enough information to preserve the amount of physical law also may play a role as to if or not additional dimensions for cosmological dynamics are necessary. more...
- Published
- 2018
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3. A New Model of the Birth of the Universe
- Author
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Alexey Belyaev
- Subjects
Cosmic age problem ,Physics ,De Sitter universe ,Astronomy ,Big Rip ,Non-standard cosmology ,Flatness problem ,Scale factor (cosmology) ,Particle horizon ,Metric expansion of space - Published
- 2017
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4. Does the cosmological principle exist in the rotating Universe?
- Author
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L. M. Chechin
- Subjects
Physics ,Big Rip ,Astronomy and Astrophysics ,Astrophysics ,Cosmological constant ,01 natural sciences ,Particle horizon ,Ekpyrotic universe ,Metric expansion of space ,Perfect Cosmological Principle ,Theoretical physics ,De Sitter universe ,0103 physical sciences ,010306 general physics ,010303 astronomy & astrophysics ,Flatness problem - Abstract
We find the probability density distribution of torque orientations in the Universe for the entire period of its evolution. It is shown that in the early Universe the orientation of its spin is random, and the cosmological principle is satisfied. This result is naturally consistent with the CMBisotropy. In the modern Universe the rotation axis direction becomes anisotropic, and the cosmological principle, strictly speaking, is not satisfied. This is confirmed by the large-scale anisotropy in the distribution of space objects and by the torque alignment direction. But since the value of the angular velocity of our Universe is $$\omega_{U_{n}}\sim10^{-19}\;\text{Hz}$$ , finding of such rotation and its influence on the natural processes is extremely difficult. So today dominates the view that the Universe is isotropic, and the cosmological principle is satisfied in it. more...
- Published
- 2017
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5. Wormholes in fractional action cosmology
- Author
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Rami Ahmad El-Nabulsi
- Subjects
Physics ,010308 nuclear & particles physics ,Phantom energy ,General Physics and Astronomy ,Big Rip ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Particle horizon ,Metric expansion of space ,General Relativity and Quantum Cosmology ,Theoretical physics ,Classical mechanics ,De Sitter universe ,0103 physical sciences ,Dark energy ,Wormhole ,010306 general physics ,Scale factor (cosmology) - Abstract
In this work we study wormholes solutions based on fractional action cosmology. We discuss cosmic dynamics of the universe in the presence of wormhole and wormhole wave function in closed Friedmann–Robertson–Walker (FRW) universe. We have observed that cosmic acceleration with traversable wormhole may be realized without the need of exotic matter like dark and phantom energy unless the scale factor of the universe obeys a power law dominated by a negative fractional parameter, which is constrained from type Ia supernovae data. Besides, we have derived wormholes wave function in a closed FRW universe and we have found that a wormhole can survive in the presence of quantum effects only if the expansion of the universe is accelerated with time. more...
- Published
- 2017
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6. About the Universe
- Author
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Angel Fierros Palacios
- Subjects
Physics ,De Sitter universe ,media_common.quotation_subject ,Big Rip ,Astrophysics ,Zero-energy universe ,Flatness problem ,Universe ,Scale factor (cosmology) ,Particle horizon ,Metric expansion of space ,media_common - Abstract
In this paper, it is proposed that the size of the classical electron, which is a stable elemental particle with the smallest concentration of matter in Nature, can be used to explain the very big size of the Universe. In order to reach that objective, the apparent size of heavenly bodies as seemed each other at very big distances in space, is used as a fundamental concept. Also, it is proved that the size, shape, mass, and future of the Universe are ruled by the speed of light, and the range of gravitational interactions. more...
- Published
- 2017
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7. Validity of Expanding Universe Theory—Static Universe Still Consistent with Hubble’s Law
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Yosuke Yashio
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Physics ,010308 nuclear & particles physics ,05 social sciences ,Big Rip ,Astronomy ,01 natural sciences ,Particle horizon ,Metric expansion of space ,De Sitter universe ,Hubble volume ,0502 economics and business ,0103 physical sciences ,Static universe ,Flatness problem ,Astrophysics::Galaxy Astrophysics ,050203 business & management ,Scale factor (cosmology) - Abstract
This note questions the validity of the Expanding Universe Theory with simple mathematics and shows Static Universe is still consistent with Hubble’s Law without assumption of expansion of the space (or the universe). If we had an explosion of a huge cel... more...
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- 2017
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8. A Possible Alternative to the Accelerating Universe IV
- Author
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F. R. Tangherlini
- Subjects
Physics ,010504 meteorology & atmospheric sciences ,media_common.quotation_subject ,Big Rip ,Astrophysics ,01 natural sciences ,Particle horizon ,Universe ,Metric expansion of space ,De Sitter universe ,Hubble volume ,0103 physical sciences ,010303 astronomy & astrophysics ,Flatness problem ,Scale factor (cosmology) ,0105 earth and related environmental sciences ,media_common - Abstract
This work briefly reviews and extends the author’s three previous works (2015), Journal of Modern Physics, 6, 78-87, and 1360-1370; (2016), 7, 1829-1844 that propose as an alternative to the accelerating ΛCDM universe, the decelerating Einstein de Sitter (EdS) universe, in which dark energy is a different phase of dark matter located only in intergalactic space (IGS), and that instead of a negative pressure, it has an index of refraction n≈1.50, and hence a reduced speed of light c / n through it. This allows the EdS universe to expand the extra distance necessary to obtain the diminished brightness of the Type Ia supernovae. In view of the recent suggestion that the universe is not accelerating, but possibly expanding uniformly, a table is given comparing both the accelerating and uniformly expanding universes with the EdS universe supplemented by the reduced speed of light. It is shown that fitting the uniformly expanding universe leads to a smaller value of n, and hence too short an age for the EdS universe, unlike the case with fitting the accelerating universe. The main result is that the proposed reduced speed of light in the IGS predicts discordant redshifts. It is shown that the current explanation of “accidental superposition,” is most likely insufficient to explain the number of observations, and that the present proposal could make up the difference. It can be tested astronomically, as illustrated in a figure. more...
- Published
- 2017
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9. The Universe at Lattice-Fields
- Author
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Giovanni Guido and Gianluigi Filippelli
- Subjects
Physics ,010308 nuclear & particles physics ,media_common.quotation_subject ,Big Rip ,01 natural sciences ,Particle horizon ,Universe ,Metric expansion of space ,Theoretical physics ,Classical mechanics ,De Sitter universe ,0103 physical sciences ,Dark energy ,Zero-energy universe ,010303 astronomy & astrophysics ,Flatness problem ,media_common - Abstract
We formulate the idea of a Universe crossing different evolving phases where in each phase one can define a basic field at lattice structure (Uk) increasing in mass (Universe-lattice). The mass creation in Uk has a double consequence for the equivalence “mass-space”: Increasing gravity (with varying metric) and increasing space (expansion). We demonstrate that each phase is at variable metric beginning by open metric and to follow a flat metric and after closed. Then we define the lattice-field of intersection between two lattice fields of base into universe and we analyse the universe in the Nucleo-synthesis phase (intersection-lattice ) and in the that of recombination (intersection-lattice ). We show that the phase is built on the intersection of the lattices of the proton (Up) and electron (Ue) or . We show UH to be at variable metric (open in the past, flat in the present and closed in the future). Then, we explain some fundamental aspects of this universe UH: Hubble’s law by creating the mass-space in it, its age (13.82 million of Years) as time for reaching the flat metric phase and the value of critic density. In last we talk about dark universe lattice , having hadronic nature, and calculating its spatial step and its density in present phase of . more...
- Published
- 2017
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10. A Wave Function for the Spin of the Early Universe Derived from the Wheeler-DeWitt Equation
- Author
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Juan Carlos Echaurren
- Subjects
Physics ,General Relativity and Quantum Cosmology ,symbols.namesake ,De Sitter universe ,Quantum mechanics ,symbols ,Big Rip ,Zero-energy universe ,Hartle–Hawking state ,Flatness problem ,Particle horizon ,Scale factor (cosmology) ,Metric expansion of space - Abstract
The wave function for the spin the early universe is obtained through the adaption of the quantum formalism to one solution of the Wheeler-DeWitt’s equation [1], associated with the wave function of the universe. In addition, some observations performed by Stephen Hawking in relation to the vorticity of the universe [2] are used. This wave function for the spin could be used for indirectly to demonstrate the presence of dark matter in the universe. more...
- Published
- 2017
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11. From the Oscillating Universe to Relativistic Energy: A Review
- Author
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Carmine Cataldo
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Physics ,010308 nuclear & particles physics ,media_common.quotation_subject ,Big Rip ,Hypersphere ,Simple harmonic motion ,01 natural sciences ,Particle horizon ,Universe ,Theoretical physics ,Classical mechanics ,De Sitter universe ,0103 physical sciences ,Speed of light ,Ball (mathematics) ,010306 general physics ,media_common - Abstract
We hypothesize a closed Universe belonging to the oscillatory class. More precisely, we postulate a Universe that evolves following a simple harmonic motion whose pulsation is equal to the ratio between the speed of light and the mean radius of curvature. The existence of at least a further spatial dimension is contemplated. Although the space we are allowed to perceive is curved, since it is identifiable with a hypersphere whose radius depends on our state of motion, the Universe in its entirety, herein assimilated to a four-dimensional ball, is to be considered as being flat. All the points are replaced by straight line segments: In other terms, what we perceive as being a point is actually a straight line segment crossing the center of the above mentioned four-dimensional ball. In the light of these hypotheses, we can easily obtain the identity that represents the so called relativistic energy. In this paper we discuss, more thoroughly than elsewhere, the deduction of the so called mass-energy equivalence. Moreover, by carrying out a simple comparison with the way in which we perceive a bi-dimensional surface, the noteworthy concept of dimensional thickness is introduced. more...
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- 2017
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12. Time Enough for Our Universe
- Author
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Derek York
- Subjects
Physics ,Theoretical physics ,De Sitter universe ,media_common.quotation_subject ,Phantom energy ,Big Rip ,Steady State theory ,Flatness problem ,Universe ,Particle horizon ,media_common - Published
- 2019
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13. The large-scale universe: The past, the present and the future
- Author
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G. P. Cherepanov
- Subjects
010302 applied physics ,Physics ,Age of the universe ,Big Rip ,Astrophysics::Cosmology and Extragalactic Astrophysics ,02 engineering and technology ,Surfaces and Interfaces ,Cosmological constant ,Astrophysics ,Condensed Matter Physics ,01 natural sciences ,Particle horizon ,Metric expansion of space ,Ekpyrotic universe ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Mechanics of Materials ,De Sitter universe ,0103 physical sciences ,General Materials Science ,Flatness problem - Abstract
Contrary to the common approach of the general relativity, the author uses his invariant integral of physical mesomechanics to model and study the universe at the large scale of about 100 MPc in the Euclidian space. The flatness of the universe proven by numerous probes of the WMAP and PLANCK satellite missions necessitates this approach. From the invariant integral of cosmology, the interaction force of two point masses in the cosmic-gravitational field is derived. This force is proven to be a sum of two terms, the one being the Newtonian gravity and the other the repulsion force caused by the cosmological constant. Both terms make up the right-hand part of the evolution equation of the dynamic universe. Qualitatively in agreement with the FLRW and ACDM models, and WMAP and PLANCK mission data, the exact solution of this equation has provided the history of the early decelerating universe and the asymptotic description of the Big Bang, the expansion at an almost constant rate in the middle age, and the current stage of the accelerated expansion of the universe. The age of the universe is found to be equal to 12.3 billion years. It is shown that neutron stars become stable Black Holes when their masses are greater than 6.7Msun. Then, it is assumed that the universe not only expands but also revolves, and the evolution equations of the revolving and expanding universe are advanced, with the cosmological constant being defined in terms of the angular velocity of the universe. A singular solution of these evolution equations has described the history of the revolving and expanding universe, at least, up to the age of about ten billion years. Orbital velocities of stars in the Milky Way are calculated to be about 250 km/s independent of the distance of stars from the galaxy center. Using the equation of the fractal dimension of the universe as a power-law fractal, the thickness of a disk-shaped universe is found. The graviton of minimum frequency is hypothesized to be the smallest elementary particle and the building block of everything. more...
- Published
- 2016
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14. Effects of cosmological constant on clustering of Galaxies
- Author
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Sudhaker Upadhyay, Ahmed Farag Ali, Mir Faizal, and Mir Hameeda
- Subjects
Physics ,010308 nuclear & particles physics ,FOS: Physical sciences ,Big Rip ,Astronomy and Astrophysics ,Lambda-CDM model ,General Relativity and Quantum Cosmology (gr-qc) ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Cosmological constant ,Astrophysics ,Astrophysics - Astrophysics of Galaxies ,01 natural sciences ,General Relativity and Quantum Cosmology ,Particle horizon ,Metric expansion of space ,Thermodynamics of the universe ,Space and Planetary Science ,De Sitter universe ,Astrophysics of Galaxies (astro-ph.GA) ,0103 physical sciences ,Statistical physics ,010303 astronomy & astrophysics ,Flatness problem - Abstract
In this paper, we analyse the effect of the expansion of the universe on the clustering of galaxies. We evaluate the configurational integral for interacting system of galaxies in an expanding universe by including effects produced by the cosmological constant. The gravitational partition function is obtained using this configuration integral. Thermodynamic quantities, specifically, Helmholtz free energy, entropy, internal energy, pressure and chemical potential are also derived for this system. It is observed that they depend on the modified clustering parameter for this system of galaxies. It is also demonstrated that these thermodynamical quantities get corrected because of the cosmological constant., Comment: 6 pages, 1 figure, Published in MNRAS more...
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- 2016
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15. Ghost Dark Energy in a Cyclic Universe
- Author
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Ahmad Sheykhi, M. Tavayef, and Biruni Üniversitesi
- Subjects
Physics ,Cyclic ,Ghost ,Deceleration parameter ,010308 nuclear & particles physics ,General Mathematics ,Phantom energy ,General Physics and Astronomy ,Big Rip ,General Chemistry ,01 natural sciences ,Particle horizon ,Thermodynamics of the universe ,Classical mechanics ,De Sitter universe ,Dark energy ,0103 physical sciences ,General Earth and Planetary Sciences ,Zero-energy universe ,010306 general physics ,General Agricultural and Biological Sciences - Abstract
In this paper, we investigate the Ghost Dark Energy (GDE) and the Generalized Ghost Dark Energy (GGDE) in a cyclic universe in which the high-energy regime is modified by the effects of quantum gravity, causing a turnaround (and a bounce) of the universe. First, we study the non-interacting cases for both of these models. We find that, in the absence of interaction in a cyclic universe, the deceleration parameter becomes a constant; as a result, the universe cannot move from an accelerated expansion phase to a deceleration phase and so cannot reach turnaround point and starts to contract. Then, we extend our study to the interacting GDE and GGDE models. We obtain the evolution of the dark energy density, the deceleration and the equation of state parameters for these models in a cyclic universe. In this case, the transition from an accelerated expansion phase to the deceleration phase in the future (near the turnaround point) can be achieved in a cyclic universe. © 2016, Shiraz University., Research Institute for Astronomy and Astrophysics of Maragha more...
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- 2016
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16. The Product of the Calculated Impedance and the Capacitance of the Universe Solves for Planck’s Time and 8π
- Author
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Stanley A. Koren and Michael A. Persinger
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Physics ,010308 nuclear & particles physics ,media_common.quotation_subject ,Big Rip ,Shape of the universe ,01 natural sciences ,Universe ,Particle horizon ,Metric expansion of space ,Theoretical physics ,Classical mechanics ,De Sitter universe ,0103 physical sciences ,010303 astronomy & astrophysics ,Flatness problem ,Scale factor (cosmology) ,media_common - Abstract
The prominence of 8π in cosmological solutions regarding the structure of space might be accommodated by factors other than the presence of mass. When the total set is considered a LC (inductance-capacitance) circuit, the “time constant†differs from Planck’s time by a factor of 8π which satisfies the numbers of turns (N) within the geometry of a universal solenoid. The calculated separation between two concentric spherical Casimir boundaries whose energies and pressures define the current universe is ~54 μm. If the volume of the universe was held constant the linear distance of this extraordinarily flat space would require the hypothetical entanglement velocity (~1023 m·s-1) continuing until the final epoch (~1018 s) of the universe to be integrated into a singular entity. We suggest that 8π may be a reflection of the temporal properties of an implicit solenoid-like spatial structure that will ultimately be manifested quite differently as the temporal boundary of the universe is approached. Two perspectives emerge. The first reflects the topological properties of a line that become the second derivative of the surface of a sphere. The second is the shape would be extraordinarily flat. more...
- Published
- 2016
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17. Rotation of the Universe at different cosmological epochs
- Author
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L. M. Chechin
- Subjects
Physics ,010308 nuclear & particles physics ,Big Rip ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Cosmological constant ,01 natural sciences ,Particle horizon ,Metric expansion of space ,General Relativity and Quantum Cosmology ,Theoretical physics ,Classical mechanics ,Space and Planetary Science ,De Sitter universe ,0103 physical sciences ,Inflationary epoch ,010303 astronomy & astrophysics ,Flatness problem ,Scale factor (cosmology) - Abstract
A step-by-step foundation for the differential character of the Universe’s rotation is presented. First, invoking the concept of spacetime foam with spin, it is reasonable to assume that the very early Universe can be described by the Dirac equation. Second, it is shown using the Ehrenfest theorem that, from a classical point of view, the early Universe can be described by the Papapetrou equations. Third, it is stressed that our Universe can perform only rotational motion. It is shown based on the spin part of the Papapetrou equations that the Universe’s rotation depends appreciably on the physical properties of a specific cosmological epoch. The rotational angular velocity is calculated for three basic cosmological epochs: the matter-dominated epoch, the transition period (from domination of matter to domination of vacuum), and the vacuum-dominated epoch. more...
- Published
- 2016
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18. Evolution and dynamics of a matter creation model
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Supriya Pan, J. de Haro, Andronikos Paliathanasis, Reinoud Jan Slagter, Universitat Politècnica de Catalunya. Departament de Matemàtiques, and Universitat Politècnica de Catalunya. EDP - Equacions en Derivades Parcials i Aplicacions more...
- Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,unification of inflation with current cosmic acceleration ,FOS: Physical sciences ,Big Rip ,General Relativity and Quantum Cosmology (gr-qc) ,Energia fosca (Astronomia) ,01 natural sciences ,General Relativity and Quantum Cosmology ,Particle horizon ,Metric expansion of space ,Theoretical physics ,De Sitter universe ,0103 physical sciences ,Zero-energy universe ,Dark energy (Astronomy) ,Particle Creation ,010303 astronomy & astrophysics ,Flatness problem ,Mathematical Physics ,Scale factor (cosmology) ,Physics ,Cosmologia ,010308 nuclear & particles physics ,Big Crunch ,Matemàtiques i estadística [Àrees temàtiques de la UPC] ,Astronomy and Astrophysics ,Mathematical Physics (math-ph) ,Cosmology ,Classical mechanics ,Space and Planetary Science ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
In a flat Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) geometry, we consider the expansion of the universe powered by the gravitationally induced `adiabatic' matter creation. To demonstrate how matter creation works well with the expanding universe, we have considered a general creation rate and analyzed this rate in the framework of dynamical analysis. The dynamical analysis hints the presence of a non-singular universe (without the big bang singularity) with two successive accelerated phases, one at the very early phase of the universe (i.e. inflation), and the other one describes the current accelerating universe, where this early, late accelerated phases are associated with an unstable fixed point (i.e. repeller) and a stable fixed (attractor) points, respectively. We have described this phenomena by analytic solutions of the Hubble function and the scale factor of the FLRW universe. Using Jacobi Last multiplier method, we have found a Lagrangian for this matter creation rate describing this scenario of the universe. To match with our early physics results, we introduce an equivalent dynamics driven by a single scalar field and discussed the associated observable parameters compared them with the latest PLANCK data sets. Finally, introducing the teleparallel modified gravity, we have established an equivalent gravitational theory in the framework of matter creation., Comment: 15 pages (two column format), 3 figures, Some typos corrected, Published version in MNRAS more...
- Published
- 2016
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19. The scale factor in a Universe with dark energy
- Author
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O. S. Sazhina and M. V. Sazhin
- Subjects
Physics ,010308 nuclear & particles physics ,Big Rip ,Astronomy and Astrophysics ,Lambda-CDM model ,01 natural sciences ,Particle horizon ,Metric expansion of space ,Thermodynamics of the universe ,symbols.namesake ,Classical mechanics ,Space and Planetary Science ,De Sitter universe ,0103 physical sciences ,symbols ,010303 astronomy & astrophysics ,Scale factor (cosmology) ,Mathematical physics ,Hubble's law - Abstract
The solution of the Friedmann cosmological equations for the scale factor in a model of the Universe containing matter having the equation of state of dust and dark energy is considered. The equation-of-state parameter of the dark energy is taken to be an arbitrary constant w = −1.006 ± 0.045, whose value is constrained by the current observational limits. An exact solution for the scale factor as a function of physical time and conformal time is obtained. Approximate solutions have been found for the entire admissible conformal time interval with an accuracy better than 1%, which exceeds the accuracy of the determined global parameters of our Universe. This is the first time an exact solution for the scale factor describing the evolution of the Universe in a unified way, beginning with the matter-dominated epoch and ending with the infinitely remote future, has been obtained. more...
- Published
- 2016
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20. The function of the universe
- Author
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Sylvain Battisti
- Subjects
Physics ,Theoretical physics ,De Sitter universe ,Hubble volume ,General Physics and Astronomy ,Big Rip ,Flatness problem ,Particle horizon ,Scale factor (cosmology) ,Metric expansion of space ,Ekpyrotic universe - Published
- 2016
- Full Text
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21. A Hydro-Dynamical Model for Gravity
- Author
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Berbente Corneliu
- Subjects
Physics ,energy formulation ,“fluid of gravitons” ,Age of the universe ,lcsh:Motor vehicles. Aeronautics. Astronautics ,media_common.quotation_subject ,graviton emission ,age of universe ,Graviton ,Aerospace Engineering ,Big Rip ,Particle horizon ,Universe ,High Energy Physics::Theory ,General Relativity and Quantum Cosmology ,Theoretical physics ,Classical mechanics ,Control and Systems Engineering ,De Sitter universe ,Gravity well ,lcsh:TL1-4050 ,Zero-energy universe ,media_common - Abstract
A hydro-dynamical model for gravity by using an analogy with the attraction of spherical sources in incompressible fluids is proposed. Information regarding a photon-like particle called graviton is taken using an author's previous paper (6). The substance and radiation interaction due to emission of gravitons takes place via an energy field made of the emitted gravitons and filling the entire universe. The energy distribution is considered uniform at the universe scale. A consequence of the proposed model is the increasing of the universal "constant" of gravity, as a function of the age of universe. more...
- Published
- 2016
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22. On evolution of the universe
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D. A. Slavnov
- Subjects
Big Bang ,Physics ,Physics::General Physics ,Nuclear and High Energy Physics ,Radiation ,010308 nuclear & particles physics ,media_common.quotation_subject ,Big Rip ,Astrophysics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Universe ,Particle horizon ,De Sitter universe ,0103 physical sciences ,Inflationary epoch ,Radiology, Nuclear Medicine and imaging ,010306 general physics ,Flatness problem ,Big Bounce ,media_common - Abstract
We consider the model of evolution of the Universe where the Big Bang is regarded as an explosion of a photon superstar. The inflationary epoch is not necessary in the model. The model describes the fundamental phenomena observed: the Universe is expanding at an increasing rate, it is homogeneous and isotropic and contains no antimatter, and its metrics is almost flat. more...
- Published
- 2016
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23. The Shell Model of the Universe: A Universe Generated from Multiple Big Bangs
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Tower Chen and Zeon Chen
- Subjects
Physics ,010308 nuclear & particles physics ,Big Crunch ,Phantom energy ,Big Rip ,Astronomy ,01 natural sciences ,Particle horizon ,Metric expansion of space ,De Sitter universe ,0103 physical sciences ,010303 astronomy & astrophysics ,Flatness problem ,Scale factor (cosmology) - Abstract
The Current Standard Model of the Universe asserts that the universe is generated from a single Big Bang event followed by inflation. There is no center to this universe, hence, no preferential reference frame to describe the motions of celestial objects. We propose a new, Shell Model of the Universe, which contends that the universe is created from multiple, concentric big bangs. Accordingly, that origin presents itself as a unique, preferential reference frame, which furnishes the simplest description of the motions of galaxies in the cosmos. This is similar in manner to how planetary motion is more straightforwardly described via a sun-centered Solar System rather than an earth-centered one. The appeal of the Shell Model of the Universe lies in its simplistic ability to resolve the paradox of quasars, explain the variability in Hubble’s Constant, and solve the problematic accelerated expansion of the universe. more...
- Published
- 2016
- Full Text
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24. Geddanken Experiment for Quark Star Idea, Quantum Wavelength Limit, Minimum Time, and Early Universe Temperature, from First Principles
- Author
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Andrew Beckwith
- Subjects
Physics ,Theoretical physics ,Classical mechanics ,De Sitter universe ,Quantum cosmology ,Heat death of the universe ,Big Rip ,Zero-energy universe ,Flatness problem ,Particle horizon ,Big Bounce - Abstract
We initially look at a non singular universe representation as given by Rovelli and Vidotto, in terms of a quantum bounce, via minimum mass quark stars, as a start of how to estimate of entropy and also of the number of operations of an expanding universe. The bench mark used is, to after considering a quark star, to look at the mass of a universe, estimated, and from there, we can obtain the entropy if we look at the Schwartzshield radii of a universe, and then the radii of the universe about 380,000 years after the big bang. In the latter, we show how to get the number of operations as akin to the reasoning used by Seth Lloyd, in 2001, and also from there close with a few comments as to the “naturalness” of heavy Gravity from this formulation of entropy, which is based upon a start of considering what is a Planck star, as far as minimum quantum effects in Black hole physics, and by extension early universe cosmology. more...
- Published
- 2016
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25. Bulk viscous quintessential inflation
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Supriya Pan, Jaume Haro, Universitat Politècnica de Catalunya. Departament de Matemàtiques, and Universitat Politècnica de Catalunya. EDP - Equacions en Derivades Parcials i Aplicacions
- Subjects
bulk viscous ,General relativity ,media_common.quotation_subject ,quintessence ,FOS: Physical sciences ,Big Rip ,General Relativity and Quantum Cosmology (gr-qc) ,01 natural sciences ,Particle horizon ,General Relativity and Quantum Cosmology ,Metric expansion of space ,Theoretical physics ,De Sitter universe ,0103 physical sciences ,nonsingular ,010303 astronomy & astrophysics ,Mathematical Physics ,media_common ,Physics ,Inflation (cosmology) ,Cosmologia ,010308 nuclear & particles physics ,Matemàtiques i estadística [Àrees temàtiques de la UPC] ,Astronomy and Astrophysics ,Inflation ,Universe ,Cosmology ,Space and Planetary Science ,Inflationary epoch - Abstract
The incorporation of bulk viscosity process to General Relativity leads to the appearance of nonsingular backgrounds that, at early and late times, depict an accelerated universe. These backgrounds could be analytically calculated and mimicked, in the context of General Relativity, by a single scalar field whose potential could also be obtained analytically. We will show that, we can build viable backgrounds that, at early times, depict an inflationary universe leading to a power spectrum of cosmological perturbations which match with current observational data, and after leaving the inflationary phase, the universe suffers a phase transition needed to explain the reheating of the universe via gravitational particle production, and finally, at late times, it enters into the de Sitter phase that can explain the current cosmic acceleration., Version accepted for publication in IJMPD more...
- Published
- 2018
26. Modeling holographic dark energy with particle and future horizons
- Author
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Samuel Lepe and Miguel Cruz
- Subjects
Physics ,Nuclear and High Energy Physics ,010308 nuclear & particles physics ,Entropy production ,Holography ,Big Rip ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,General Relativity and Quantum Cosmology (gr-qc) ,01 natural sciences ,General Relativity and Quantum Cosmology ,Coincidence ,Particle horizon ,law.invention ,Theoretical physics ,Singularity ,law ,0103 physical sciences ,Dark energy ,lcsh:QC770-798 ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,010303 astronomy & astrophysics ,Entropy (arrow of time) - Abstract
In this work we explore some cosmological properties coming from the particle and future horizons when are considered as candidates to model the dark energy sector within a holographic context in a flat Friedmann-Lemaitre-Robertson-Walker universe; we focus on some thermodynamics characteristics of the resulting dark energy scenario. Within the interacting scheme for cosmological fluids we obtain that in the dark sector, the dark energy fluid will always have negative entropy production and additionally, the positivity for the entropy and temperature can not be guaranteed simultaneously; this result holds for both horizons. However, this last issue can be solved if chemical potential is introduced in the thermodynamics description. For the non interacting approach, we obtain similar results as those of the single fluid description for the entropy behavior. We also find that the model admits a genuine big rip singularity when the dark energy density is sketched by the future horizon, in consequence the resulting parameter state can cross to the phantom regime. For the particle horizon case the cosmological fluid can emulate ordinary matter and the coincidence parameter has a decreasing behavior when the future horizon is elected., Comment: 19 pages, no figures. To appear in Nuclear Physics B more...
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- 2018
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27. Gravitational collapse and structure formation in an expanding universe
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Jasjeet Singh Bagla and Pritpal Kaur Sandhu
- Subjects
Physics ,Friedmann equations ,Big Rip ,Non-standard cosmology ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Particle horizon ,Education ,Metric expansion of space ,General Relativity and Quantum Cosmology ,Theoretical physics ,symbols.namesake ,De Sitter universe ,Gravitational collapse ,symbols ,Flatness problem ,Astrophysics::Galaxy Astrophysics - Abstract
We use Newtonian formalism to motivate the form of Friedmann equations that describe the expansion of the universe in the standard cosmological model. We use the same formalism to study the evolution of density perturbations in the universe. We show that a simple model like spherical collapse can be used to estimate the characteristics of halos of galaxies and clusters of galaxies. more...
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- 2015
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28. Dark Energy: Accelerating Expansion of the Universe and of the Higgs Quantum Space
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Jacob Schaf
- Subjects
Physics ,Gravitation ,De Sitter universe ,Phantom energy ,Dark energy ,Big Rip ,Astrophysics ,Zero-energy universe ,Particle horizon ,Metric expansion of space - Abstract
Dark energy, accelerating the expansion of the universe, is fourteen times larger than the ordinary mass-energy in the universe. So much energy can be found only in the scenario of the creation of the universe. Quantum condensation of the Higgs condensate (HC), after the Big-Bang, when the temperature fell through 10 15 Kelvin, liberates hundreds of GeV/boson. The Higgs potential energy well has the form: U(ρ) = −n(ϕ ϕ) + m(ϕ ϕ) 2 , where n > m, ϕ is a complex order parameter and ρ = ϕ ϕ is the condensate density. The depth of this potential well is generic and uniform throughout the universe. If ρ > n/m, the HC can lower its energy by freely expanding its volume, which is related with the accelereted expansion of the universe. Recent experimental observations, achieved with the help of the tightly synchronized clocks in orbit, show that the Higgs Quantum Space (HQS), ruling the inertial motion of matter and propagating light, is circulating round earth, round the sun and round the galactic center according to velocity fields, consistent with the local main astronomical motions, thereby appropriately creating the observed gravitational dynamics. In these Keplerian velocity fields, earth is very closely stationary with respect to the HQS, which explains the isotropy of light with respect to earth. It also explains the absence of the gravitational slowing of the GPS clocks, predicted by General Relativity, but not observed. This HQS-dynamics however cannot explain why the recession between the galaxies causes no light anisotropy. The isotropy of light proves that this recession too lets earth, the sun and the Milky-Way galaxy stationary with respect to the HQS. Obviously, this becomes possible only if the expansion of the universe is expansion of the HQS itself, showing that the expansion of the universe follows perfectly the expansion of the HQS itself. more...
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- 2015
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29. Model of a multi-element universe
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Alexander Shatskiy, I. D. Novikov, and Dmitry Novikov
- Subjects
Physics ,media_common.quotation_subject ,Big Rip ,Steady State theory ,Astronomy and Astrophysics ,Particle horizon ,Universe ,Ekpyrotic universe ,Theoretical physics ,Space and Planetary Science ,De Sitter universe ,Flatness problem ,Scale factor (cosmology) ,media_common - Abstract
New exact models of a multi-element Universe consisting of an infinite number of elements with different physical properties are considered.
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- 2015
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30. Thermodynamic Equilibrium and Rise of Complexity in an Accelerated Universe
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Nematollah Riazi and Hooman Moradpour
- Subjects
Physics ,Physics and Astronomy (miscellaneous) ,010308 nuclear & particles physics ,Thermodynamic equilibrium ,Heat death of the universe ,General Mathematics ,media_common.quotation_subject ,Big Rip ,Steady State theory ,01 natural sciences ,Universe ,Particle horizon ,Metric expansion of space ,Theoretical physics ,De Sitter universe ,Quantum mechanics ,0103 physical sciences ,010306 general physics ,media_common - Abstract
Observational data (Supernovae type Ia data) indicate that the rate of the universe expansion is increasing, which means that, in the framework of General Relativity, the current phase of the expansion is due to an unknown source of energy. Therefore, the nature of dominated fluid in cosmos, as the source of energy, is mysterious. Here, by considering this property of current accelerating phase along with the concept of thermodynamics equilibrium we try to find possible values for the state parameter (ω) of the dominated fluid in a (n+1)-dimensional Friedmann-Robertson-Walker universe. Our results are compatible with previous work for Gauss-Bonnet gravity and point to a universe which is so close to its thermodynamic equilibrium state. By the evolution of the cosmos, the baryonic content of the cosmos is participating in longer range interactions, including gravity and electromagnetism, and structure formation is begun which leads to an increase in the complexity content of the universe. Therefore, a true model for the cosmos should show this rise of complexity and information. In order to achieve this goal, we introduce a simple model including free particles in an expanding box and try to count the number of the states of energy. This configuration shows that the entropy of these number of states as the measure for complexity is increased when dominated fluid satisfies special condition (ω ≥ −1) which is compatible with the results of the Supernovae type Ia data and the thermodynamic equilibrium conditions. Finally, We see that the rate of increase in the complexity content of the universe increases in the \(\omega \rightarrow -1\) limit. more...
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- 2015
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31. Cosmological Entropy and Seeking of Genesis of Time
- Author
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Rakesh Teja Konduru
- Subjects
Physics ,Heat death of the universe ,De Sitter universe ,Quantum mechanics ,Hubble volume ,Big Rip ,Cosmological constant ,Flatness problem ,Particle horizon ,Metric expansion of space ,Mathematical physics - Abstract
Influenced with symmetry of entropy and time in nature, we tried to invoke relation between entropy and time in space-time with new dimension. And also provided how Hubble’s constant related with entropy of universe. Discussed about how entropy of universe behaves at different temperatures and at different time values of universe. We showed that age of universe is equivalent to Hubble’s constant. And showed how naturally entropy arrives from the manipulations in gravity from Einstein’s equation “00â€. And from these results we concluded that universe is isotropic, homogeneous with negative space curvature i.e. K= -1 but not flat K=0 (which doesn’t explain acceleration and deceleration of universe). From these results of gravity, entropy, temperature and time we discussed the genesis of time. And proposed that at absolute zero temperature universe survives as a superconductor and that particular temperature is called as “Critical Absolute Temperature (TAB). And genesis of time occurs at first fluxon repulsion in the absolute zero temperature of universe. more...
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- 2015
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32. Creation of a Non-Expanding, Non-Singular Universe
- Author
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Walter Petry
- Subjects
Physics ,Cold dark matter ,De Sitter universe ,Big Rip ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Zero-energy universe ,Flatness problem ,Particle horizon ,Scale factor (cosmology) ,Metric expansion of space - Abstract
A theory of gravitation in flat space-time is applied to homogeneous, isotropic cosmological models. There are non-singular cosmological models. A natural interpretation is a non-expanding universe. The redshift is an intrinsic effect and not a Doppler effect. The universe contains only energy in the beginning, i.e. no matter exists. In the course of time matter and radiation are created from energy where the whole energy is conserved. Matter increases with time but a certain time after the beginning of the universe the creation of matter is finished and the universe appears like a static one. A modified Hubble law is considered which may explain the high redshifts of objects in the universe without the assumption of dark energy. more...
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- 2015
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33. Accelerating Expansion in a Closed Universe
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Martin Tamm
- Subjects
Physics ,Theoretical physics ,De Sitter universe ,Phantom energy ,Dark energy ,Big Rip ,Cosmological constant ,Particle horizon ,Scale factor (cosmology) ,Metric expansion of space - Abstract
In this paper, I suggest a possible explanation for the accelerating expansion of the universe. This model does not require any dark energy or quintessence. Rather, the idea is to suggest a different view on the origin of general relativity. Since it is very difficult to say something in general, I will mainly restrict myself to the case of very low curvature. The question about the underlying reasons for the acceleration is also closely related to the question whether the universe is a finite or infinite. It is part of the purpose of this paper to argue that a phase of accelerating expansion may be very well compatible with the idea of a closed universe. more...
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- 2015
- Full Text
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34. The Reversible Cyclic Universe in the Reversible Multiverse and the Reversible String Theory
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Ding-Yu Chung
- Subjects
Physics ,Thermodynamics of the universe ,Classical mechanics ,Heat death of the universe ,De Sitter universe ,Quantum mechanics ,Phantom energy ,Big Rip ,Zero-energy universe ,Flatness problem ,Particle horizon - Abstract
The paper posits that the multiverse is reversible, so all universes in the multiverse are reversible cyclic universes which have the inexhaustible resources of space-time to expand. The collision of expanding universes is permanently irreversible, forbidden in the reversible multiverse, so every universe is surrounded by the zero-energy interuniversal void as the permanent gap among universes to keep universes apart. A zero-sum energy dual universe of positive energy universe and negative energy universe can be created in the interuniversal void, and the new dual universe is again surrounded by the interuniversal void. This paper also posits the reversible string theory with oscillating space-time dimension number oscillating between 11D (space-time dimension) and 4D without the conventional compactization of string. Dimension number decreases with decreasing speed of light, decreasing vacuum energy, and increasing rest mass. The 4D and the 11D have zero and the highest vacuum energies, respectively. The universes in the reversible multiverse oscillate reversibly between high and low dimension numbers. Under symmetry breaking as in our universe, the positive energy universe as our observed universe absorbed the interuniversal void, while the negative energy universe did not. The interuniversal void has zero vacuum energy, so the absorption of the interuniversal void by the positive energy universe forced the positive energy 10D universe with high vacuum energy to be transformed into the positive energy 4D universe with zero vacuum energy, resulting in the inflation followed by the Big Bang. The negative energy universe undergoes dimension number oscillation between 4D and 10D dimension by dimension. The negative energy >4D universe is hidden, and the negative energy 4D universe appears as dark energy. The calculated percentages of dark energy, dark matter, and baryonic matter and the calculated time for dark energy to start are in good agreements with the observed values. more...
- Published
- 2015
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35. Distribution of Mass and Energy in Closed Model of the Universe
- Author
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Fadel A. Bukhari
- Subjects
Physics ,Cold dark matter ,Big Crunch ,De Sitter universe ,Phantom energy ,Dark energy ,Astronomy ,Big Rip ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Flatness problem ,Particle horizon - Abstract
The universe’s horizon distance and volume are constructed in the closed cosmic model. The universe horizon distance distribution increases constantly for t tme and decreases for t > tme. However, the universe’s horizon volume shows a sudden reduction in the range t = 0.5 Gyr - tme due to the change of the universe space from flat to curved then closed in the interval 15.1261 Gyr ≤ t ≤ tme. On the other hand, this distribution exhibits an abrupt rise in the range t = tme - t* due to the change of the universe space from closed then curved to flat in the interval 39.3822 ≤ t ≤ 40.7521 Gyr. The mass of radiation, matter and dark energy within the horizon volume of the universe are also investigated. These distributions reveal similar noticeable changes as the universe’s horizon volume distribution for the same reasons. The mass of radiation dominates up to t = 53221.5 yr, then the mass of matter becomes larger. Afterwards, both distributions of radiation and matter decrease while the distribution of dark energy rises until t = 10.1007 Gyr, where the mass of dark energy prevails up to t = tme. Hence, the distribution of dark energy reduces until t = 40.2892 Gyr, where the mass of matter becomes prominent again. At t = 53.6246 Gyr the masses of both matter and radiation become appreciably high such that the intercluster space will vanish and clusters of galaxies interfere with each other. Furthermore, not only the intergalactic medium will disappear, but also galaxies will collide and merge with each other to form extremely dense and close cosmological bodies. These very dense bodies will undergo further successive collisions and mergers under the action of central gravity, where the interstellar medium will vanish and the universe would develop to big crunch at tbc = 53.6251 Gyr. It is interesting to note that the horizon distance of the universe in the closed model at t = tme is in very good agreement with the maximum horizon distances in the five general cosmic models. more...
- Published
- 2015
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36. Compactified Cosmological Simulations of the Infinite Universe
- Author
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László Dobos, István Csabai, Gábor Rácz, and István Szapudi
- Subjects
Physics ,010308 nuclear & particles physics ,media_common.quotation_subject ,Mathematical analysis ,Big Rip ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,Universe ,Particle horizon ,Ekpyrotic universe ,Metric expansion of space ,Space and Planetary Science ,De Sitter universe ,0103 physical sciences ,Periodic boundary conditions ,010303 astronomy & astrophysics ,Flatness problem ,media_common ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We present a novel $N$-body simulation method that compactifies the infinite spatial extent of the Universe into a finite sphere with isotropic boundary conditions to follow the evolution of the large-scale structure. Our approach eliminates the need for periodic boundary conditions, a mere numerical convenience which is not supported by observation and which modifies the law of force on large scales in an unrealistic fashion. We demonstrate that our method outclasses standard simulations executed on workstation-scale hardware in dynamic range, it is balanced in following a comparable number of high and low $k$ modes and, its fundamental geometry and topology match observations. Our approach is also capable of simulating an expanding, infinite universe in static coordinates with Newtonian dynamics. The price of these achievements is that most of the simulated volume has smoothly varying mass and spatial resolution, an approximation that carries different systematics than periodic simulations. Our initial implementation of the method is called StePS which stands for Stereographically Projected Cosmological Simulations. It uses stereographic projection for space compactification and naive $\mathcal{O}(N^2)$ force calculation which is nevertheless faster to arrive at a correlation function of the same quality than any standard (tree or P$^3$M) algorithm with similar spatial and mass resolution. The $N^2$ force calculation is easy to adapt to modern graphics cards, hence our code can function as a high-speed prediction tool for modern large-scale surveys. To learn about the limits of the respective methods, we compare StePS with GADGET-2 \citep{Gadget2_2005MNRAS.364.1105S} running matching initial conditions. more...
- Published
- 2017
37. Does information entropy play a role in the expansion and acceleration of the Universe?
- Author
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Biswajit Pandey
- Subjects
Physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,010308 nuclear & particles physics ,Heat death of the universe ,Phantom energy ,Big Rip ,FOS: Physical sciences ,Astronomy and Astrophysics ,General Relativity and Quantum Cosmology (gr-qc) ,01 natural sciences ,Particle horizon ,General Relativity and Quantum Cosmology ,Metric expansion of space ,Theoretical physics ,Classical mechanics ,Space and Planetary Science ,De Sitter universe ,0103 physical sciences ,Zero-energy universe ,010303 astronomy & astrophysics ,Flatness problem ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We propose an interpretation of the expansion and acceleration of the Universe from an information theoretic viewpoint. We obtain the time evolution of the configuration entropy of the mass distribution in a static Universe and show that the process of gravitational instability leads to a rapid dissipation of configuration entropy during the growth of the density fluctuations making such a Universe entropically unfavourable. We find that in an expanding Universe, the configuration entropy rate is governed by the expansion rate of the Universe and the growth rate of density fluctuations. The configuration entropy rate becomes smaller but still remains negative in a matter dominated Universe and eventually becomes zero at some future time in a $\Lambda$ dominated Universe. The configuration entropy may have a connection to the dark energy and possibly plays a driving role in the current accelerating expansion of the Universe leading the Universe to its maximum entropy configuration., Comment: 4 pages, no figures, minor revision, Accepted for publication in MNRAS Letters more...
- Published
- 2017
38. A cosmic controversy
- Author
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Chris Bickel, Jia You, and Joshua Sokol
- Subjects
Physics ,Multidisciplinary ,Age of the universe ,010308 nuclear & particles physics ,Astronomy ,Big Rip ,Astrophysics ,01 natural sciences ,Physics::History of Physics ,Particle horizon ,Metric expansion of space ,Cosmic age problem ,De Sitter universe ,Hubble volume ,0103 physical sciences ,010303 astronomy & astrophysics ,Flatness problem - Abstract
Debate over the Hubble constant, the expansion rate of the universe, has exploded again. Astronomers had mostly settled on a number using a classical technique—the "distance ladder," or astronomical observations from the local universe on out. But these values conflict with cosmological estimates made from maps of the early universe and adjusted to the present day. The dispute suggests a missing ingredient may be fueling the growth of the universe. more...
- Published
- 2017
39. Super inflation mechanism and dark energy in F ( T , T G ) $F(T,T_{G})$ gravity
- Author
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A. I. Keskin
- Subjects
Physics ,010308 nuclear & particles physics ,Big Rip ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,Particle horizon ,Metric expansion of space ,General Relativity and Quantum Cosmology ,Theoretical physics ,Space and Planetary Science ,De Sitter universe ,0103 physical sciences ,Inflationary epoch ,Zero-energy universe ,010303 astronomy & astrophysics ,Flatness problem ,Scale factor (cosmology) - Abstract
There are various mechanisms that explain both the inflationary epoch of the early universe and a unification of this epoch with the other stages of the universe. In this study, we show all the expansion history of the universe and transition among of them in a single form by using the theoretical framework of $F ( T, T_{G} ) $ gravity in the context of the FRW (Friedmann-Robertson-Walker) universe. According to a particular model we obtain the unified solutions of the field equations. Without using any scalar field description we especially present the super inflation mechanism composed of three phase regions which describes the evolution of the early universe. The mechanism begins with a vacuum state and then follows a super accelerated period where there are two regions. The first continues in a quintessential field, and the second is a region where the radiation is created. Furthermore, we verified this inflationary mechanism by using the spectral index parameter and the scalar tensor ratio, i.e., $n_{s}$ , $r$ , and calculated the ratio of radiation emergent from the quintessence field. This creation should be in a certain rate in the early universe otherwise we show that the universe cannot survive and continue to expand. Also, we have obtained a phantom solution of the model that shows two regions which are compatible with the recent cosmological observations. In one respect, it is observed that the late time expansion of the universe is similar to the early time inflation. more...
- Published
- 2017
- Full Text
- View/download PDF
40. Bianchi-I cosmological model and crossing singularities
- Author
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Alessandro Tronconi, G. Venturi, Ekaterina O. Pozdeeva, Sergey Yu. Vernov, Alexander Yu. Kamenshchik, Kamenchtchik, A., Pozdeeva, E., Tronconi, A., Venturi, G., and Vernov, S.
- Subjects
Physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,010308 nuclear & particles physics ,Big Crunch ,FOS: Physical sciences ,Big Rip ,General Relativity and Quantum Cosmology (gr-qc) ,Cosmological constant ,01 natural sciences ,Particle horizon ,General Relativity and Quantum Cosmology ,Metric expansion of space ,symbols.namesake ,Classical mechanics ,De Sitter universe ,Friedmann–Lemaître–Robertson–Walker metric ,0103 physical sciences ,symbols ,010306 general physics ,Flatness problem ,cosmologia, singolarita', universo Bianchi - I ,Mathematical physics ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We consider a rather simple method for the description of the Big Bang - Big Crunch cosmological singularity crossing. For the flat Friedmann universe this method gives the same results as more complicated methods, using Weyl symmetry or the transitions between the Jordan and Einstein frames. It is then easily generalized for the case of a Bianchi-I anisotropic universe. We also present early-time and late-time asymptotic solutions for a Bianchi-I universe, filled with a conformally coupled massless scalar field., 11 pages, v2: accepted for publication in Phys. Rev. D more...
- Published
- 2017
41. Can we remove the systematic error due to isotropic inhomogeneities?
- Author
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Ken-ichi Nakao and Hiroyuki Negishi
- Subjects
Physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,010308 nuclear & particles physics ,Cosmological principle ,FOS: Physical sciences ,Shape of the universe ,Big Rip ,General Relativity and Quantum Cosmology (gr-qc) ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,General Relativity and Quantum Cosmology ,Particle horizon ,Metric expansion of space ,Perfect Cosmological Principle ,Classical mechanics ,De Sitter universe ,0103 physical sciences ,010303 astronomy & astrophysics ,Flatness problem ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Usually, we assume that there is no inhomogeneity isotropic in terms of our location in our uni- verse. This assumption has not been observationally confirmed yet in sufficient accuracy, and we need to consider the possibility that there are non-negligible large-scale isotropic inhomogeneities in our universe. The existence of large-scale isotropic inhomogeneities affects the determination of the cosmological parameters. In particular, from only the distance-redshift relation, we can not dis- tinguish the inhomogeneous isotropic universe model from the homogeneous isotropic one, because of the ambiguity in the cosmological parameters. In this paper, in order to avoid such ambiguity, we consider three observables, the distance-redshift relation, the fluctuation spectrum of the cosmic microwave background radiation(CMBR) and the scale of the baryon acoustic oscillation(BAO), and compare these observables in two universe models; One is the inhomogeneous isotropic uni- verse model with the cosmological constant and the other is the homogeneous isotropic universe model with the dark energy other than the cosmological constant. We show that these two universe models can not predict the same observational data of all three observables but the same ones of only two of three, as long as the perturbations are adiabatic. In principle, we can distinguish the inhomogeneous isotropic universe from the homogeneous isotropic one through appropriate three observables, if the perturbations are adiabatic., Comment: 23pages, 4figure. arXiv admin note: text overlap with arXiv:1505.02472 more...
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- 2017
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- View/download PDF
42. Growth of matter perturbation in quintessence cosmology
- Author
-
Fargiza A. M. Mulki and H. R. T. Wulandari
- Subjects
Physics ,Big Bang ,Perfect Cosmological Principle ,De Sitter universe ,Big Rip ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Cosmological constant ,Astrophysics ,Flatness problem ,Particle horizon ,Metric expansion of space - Abstract
Big bang theory states that universe emerged from singularity with very high temperature and density, then expands homogeneously and isotropically. This theory gives rise standard cosmological principle which declares that universe is homogeneous and isotropic on large scales. However, universe is not perfectly homogeneous and isotropic on small scales. There exist structures starting from clusters, galaxies even to stars and planetary system scales. Cosmological perturbation theory is a fundamental theory that explains the origin of structures. According to this theory, the structures can be regarded as small perturbations in the early universe, which evolves as the universe expands. In addition to the problem of inhomogeneities of the universe, observations of supernovae Ia suggest that our universe is being accelerated. Various models of dark energy have been proposed to explain cosmic acceleration, one of them is cosmological constant. Because of several problems arise from cosmological constant, the ... more...
- Published
- 2017
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- View/download PDF
43. Apparent need of antimatter galaxies for the stability of the universe
- Author
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S. Beghella Bartoli and Ruggero Maria Santilli
- Subjects
Physics ,Physics::General Physics ,media_common.quotation_subject ,Astronomy ,Big Rip ,Non-standard cosmology ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Particle horizon ,Universe ,Metric expansion of space ,De Sitter universe ,Static universe ,Flatness problem ,media_common - Abstract
Fritz Zwicky’s hypothesis, according to which the cosmological redshift is due to galactic light losing energy to intergalactic media, without need of Universe expansion, seems to have been recently confirmed by recent mathematical, theoretical and experimental studies via measurements on Earth. But the return to a static universe would imply the inevitable prediction that the universe should collapse due to gravitational attractions among galaxies. In this paper, we present apparently for the first time a cosmological model in which the stability of the universe is achieved under the condition of admitting an equal number of matter and antimatter galaxies (as they are hypothesized in Isodual Theory of Antimatter) at such a large mutual distance for which gravitational interactions are neglectable. more...
- Published
- 2017
- Full Text
- View/download PDF
44. A Universe Far from Equilibrium
- Author
-
Gavin D. Bascom
- Subjects
De Sitter universe ,Heat death of the universe ,media_common.quotation_subject ,Philosophy ,Big Rip ,Flatness problem ,Universe ,Particle horizon ,Epistemology ,Metric expansion of space ,media_common ,Reference frame - Abstract
Talking precisely about the universe in terms that come from rules solely deriving from inside said universe is difficult, to say the least. This funny conundrum, namely one of not being able to separate the observer from the observed, is a central tenet for almost all the concepts in this book. When we look at time and try to deconstruct it, it is difficult because it has become tangled with space, when we try to deconstruct space it is somehow acquired a messy tangled relationship with time, and when you try to untangle them as a unit, we find that they depend on reference frames which are tangled as well! more...
- Published
- 2017
- Full Text
- View/download PDF
45. A Physical – Geometrical Model of an Early Universe
- Author
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Berbente Corneliu
- Subjects
Physics ,associated photon ,Spacetime ,Initial singularity ,lcsh:Motor vehicles. Aeronautics. Astronautics ,media_common.quotation_subject ,ordered structure ,Aerospace Engineering ,Big Rip ,singularity ,spherical wave ,Particle horizon ,Universe ,Metric expansion of space ,Theoretical physics ,primary wave ,Classical mechanics ,Control and Systems Engineering ,De Sitter universe ,lcsh:TL1-4050 ,Flatness problem ,media_common - Abstract
A physical-geometrical model for a possible early universe is proposed. One considers an initial singularity containing the energy of the whole universe. The singularity expands as a spherical wave at the speed of light generating space and time. The relations of the special theory of relativity, quantum mechanics and gas kinetics are considered applicable. A structuring of the primary wave is adopted on reasons of geometrical simplicity as well as on satisfying the conservation laws. The evolution is able to lead to particles very close to neutrons as mass and radius. The actually admitted values for the radius and mass of the universe as well as the temperature of the ground radiation (3-5 K) can be obtained by using the proposed model. more...
- Published
- 2014
- Full Text
- View/download PDF
46. Accelerated universe with inflation and a divergence-free Big Bang
- Author
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V. Majerník
- Subjects
Physics ,Big Bang ,General Relativity and Quantum Cosmology ,De Sitter universe ,Dark energy ,Big Rip ,Astronomy and Astrophysics ,Astrophysics ,Zero-energy universe ,Flatness problem ,Scale factor (cosmology) ,Particle horizon ,Mathematical physics - Abstract
We consider a two-component universe consisting of ordinary matter and vacuum energy quantitatively described by the cosmological term L c = (l/a)ρ c , where l is a quantity having the dimension of length, ρ c is the density of ordinary matter, and a is the scale factor. To justify the form of L c , we use the Maxwell-like approach to gravitation in which it is supposed that the gravitational field energy gravitates. The total energy conservation law for both cosmic components determines the mass density and the vacuum energy density as a function of the scale factor. Applying this two-component cosmic model to the present universe, the important cosmic parameters get values consistent with observations. The ratio of density parameters of ordinary matter and vacuum mass-energy, Ω m /Ω l , in today’s universe is 1/2. Interesting features of our model are (i) the existence of an inflationary phase just at the earliest era of the universe follows directly from the modified Friedmann equations, and (ii) the beginning of cosmic expansion, the Big-Bang, is singularity-free, i.e., both the mass and vacuum energy contents assume finite values at the very origin of the universe. more...
- Published
- 2014
- Full Text
- View/download PDF
47. The point of view of the universe
- Author
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Jussi Suikkanen
- Subjects
Physics ,Theoretical physics ,De Sitter universe ,Big Rip ,Steady State theory ,Cosmological constant ,Flatness problem ,Particle horizon ,Metric expansion of space ,Ekpyrotic universe - Published
- 2014
- Full Text
- View/download PDF
48. On Bianchi Type III String Cloud Universe Containing Strange Quark Matter
- Author
-
Koijam Manihar Singh and Kangujam Priyokumar Singh
- Subjects
Physics ,Particle physics ,Theoretical physics ,Cold dark matter ,De Sitter universe ,Big Rip ,Zero-energy universe ,Flatness problem ,Particle horizon ,Scale factor (cosmology) ,Metric expansion of space - Abstract
Considering Bianchi type III space-time we present the model Universe containing strange quark matter which is expanding, anisotropic, with a sign of dark energy that help in accelerated expansion of this Universe. It is also seen that the model Universe contains both particles and strings but ultimately will have fluid containing particles only. This model which we consider here is acceptable in view of the present observations of the Universe. Some physical and geometrical properties are also discussed. more...
- Published
- 2014
- Full Text
- View/download PDF
49. Structure of Relatively Accelerating Universe
- Author
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Aloysius Sebastian
- Subjects
Physics ,Classical mechanics ,De Sitter universe ,Big Crunch ,Phantom energy ,Big Rip ,Zero-energy universe ,Flatness problem ,Particle horizon ,Metric expansion of space - Abstract
This article is about the structure of expanding universe. Here I am trying to create a structural model of universe according to my thoughts. Studies showthat universe is accelerating its rate of expansion. Here I am trying to get some conclusions according to my thoughts. In my opinion, our universe is under a gravitational frame with all the matters in it. In this gravitational frame of universe we can consider our universe as a closed system and the empty space outside the frame as an open system. There are two possibilities we can find. One is relative motion of the objects inside the frame. By this way we can feel the universe is accelerating its expansion, but it is not. Another one is the vacuum energy absorption and negative pressure inside the frame. According to this thought, we can say that universe is accelerating and it can continue its motion at present conditions on it, even the force created by the big bang is decreasing. The other point is that, once the absorbed vacuum can create a negative pressure inside the frame, there is no need for the concept of dark energy in our universe [1]. According to this model, negative pressure inside the frame will be created by the absorbed vacuum from the space. So the existence of dark energy can be questioned. In this model, dark energy doesn't play any role in the expansion or rate of acceleration on the expansion of universe. So the dark energy doesn’t exist in this model. During the absorption of vacuum to the frame, it will increase the volume of the frame. It will create free spaces inside the frame to accommodate the vacuum inside the frame. The rest of the absorbed vacuum will move to the center of the frame by the action against gravity and the force created by the big bang. It will increase the density of the absorbed vacuum in the center and can create the negative pressure on the frame to pull it outside to the empty space. It will cause the acceleration on expansion of universe. These things are explained deeply in this article. And here it also explains the destiny of universe according to the frame and expansion of universe. more...
- Published
- 2014
- Full Text
- View/download PDF
50. Non-collapsing wave functions in an infinite universe
- Author
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Emmanuel Moulay, XLIM (XLIM), Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), and Université de Poitiers
- Subjects
Physics ,010308 nuclear & particles physics ,media_common.quotation_subject ,General Physics and Astronomy ,Big Rip ,Observable ,Physics and Astronomy(all) ,01 natural sciences ,lcsh:QC1-999 ,Particle horizon ,Universe ,Wave function collapse ,Classical mechanics ,[PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph] ,De Sitter universe ,Quantum state ,Cosmological principle ,0103 physical sciences ,Infinite universe ,010303 astronomy & astrophysics ,Flatness problem ,lcsh:Physics ,media_common - Abstract
Open access; International audience; The main goal of this article is to show that there exist wave functions which never collapse in an infinite universe. These are the quantum states of similar quantum systems evolving in similar observable universes. more...
- Published
- 2014
- Full Text
- View/download PDF
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