scholarly journals From General Relativity to A Simple-Harmonically Oscillating Universe, and Vice-Versa: A Review

2017 ◽  
Vol 9 (1) ◽  
pp. 86 ◽  
Author(s):  
Carmine Cataldo
Keyword(s):  
General Relativity ◽  
Cosmological Constant ◽  
Gravitational Constant ◽  
Spatial Dimension ◽  
Global Symmetry ◽  
Mass Energy ◽  
Fluid Equation ◽  
Energy Equivalence ◽  
Curvature Parameter ◽  
The Universe

In this paper two different lines of reasoning are followed in order to discuss a Universe that belongs to the so-called oscillatory class. In the first section, we start from the general writing of the first Friedmann – Lemaître equation. Taking into account mass – energy equivalence, the so-called fluid equation is immediately deduced, with the usual hypotheses of homogeneity and isotropy, once identified the evolution of the Universe with an isentropic process. Considering equal to zero the curvature parameter, and carrying out an opportune position concerning the so-called cosmological constant, we obtain an oscillating class, to which a simple-harmonically oscillating Universe evidently belongs. In the second section, we start from a simple-harmonically oscillating Universe, hypothesized globally flat and characterized by at least a further spatial dimension. Once defined the density, taking into account a global symmetry elsewhere postulated, we carry out a simple but noteworthy position concerning the gravitational constant. Then, once established the dependence between pressure and density, we deduce, by means of simple mathematical passages, the equations of Friedmann – Lemaître, without using Einstein’s Relativity.

scholarly journals Generalized Phenomenological Models of Dark Energy

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Prasenjit Paul ◽  
Rikpratik Sengupta
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Energy Density ◽  
Cosmological Constant ◽  
Phenomenological Models ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Free Parameters ◽  
The Universe ◽  
Matter Energy

It was first observed at the end of the last century that the universe is presently accelerating. Ever since, there have been several attempts to explain this observation theoretically. There are two possible approaches. The more conventional one is to modify the matter part of the Einstein field equations, and the second one is to modify the geometry part. We shall consider two phenomenological models based on the former, more conventional approach within the context of general relativity. The phenomenological models in this paper consider a Λ term firstly a function of a¨/a and secondly a function of ρ, where a and ρ are the scale factor and matter energy density, respectively. Constraining the free parameters of the models with the latest observational data gives satisfactory values of parameters as considered by us initially. Without any field theoretic interpretation, we explain the recent observations with a dynamical cosmological constant.

scholarly journals Faster than Light: Again on the Lorentz Transformations

2016 ◽  
Vol 8 (6) ◽  
pp. 17 ◽  
Author(s):  
Carmine Cataldo
Keyword(s):  
Special Relativity ◽  
Empirical Evidence ◽  
Spatial Dimension ◽  
Lorentz Transformations ◽  
Mass Energy ◽  
Formal Validity ◽  
Energy Equivalence ◽  
Faster Than Light

<p class="1Body">The Lorentz transformations can be considered, without any doubt whatsoever, as the backbone of the theory of Special Relativity. Nonetheless, both the conventional derivation of the transformations and the meaning commonly assigned to them have been often savagely criticized, to the extent that, despite an alleged empirical evidence, the whole Special Relativity, in several occasions, has been brought into question. This paper is finalized to more thoroughly discuss a line of reasoning, elsewhere used in order to carry out an alternative deduction of the mass – energy equivalence, that may lead, amongst other things, towards the assignment of a new meaning to the Lorentz transformations, without any loss of formal validity. The transformations can be alternatively deduced once assumed some noteworthy hypotheses concerning our Universe, among which the existence of at least a further spatial dimension stands out. It is fundamental to underline that time is supposed as being absolute.</p>

scholarly journals CAN THE EXISTENCE OF DARK ENERGY BE DIRECTLY DETECTED?

2009 ◽  
Vol 24 (18n19) ◽  
pp. 3426-3436 ◽  
Author(s):  
MARTIN L. PERL
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Energy Density ◽  
Total Mass ◽  
Mass Density ◽  
Mass Energy ◽  
Dark Energy Density ◽  
Astronomical Observations ◽  
Expansion Of The Universe ◽  
The Universe

Over the last decade, astronomical observations show that the acceleration of the expansion of the universe is greater than expected from our understanding of conventional general relativity, the mass density of the visible universe, the size of the visible universe and other astronomical measurements. The additional expansion has been attributed to a variety of phenomenon that have been given the general name of dark energy. Dark energy in the universe seems to comprise a majority of the energy in the visible universe amounting to about three times the total mass energy. But locally the dark energy density is very small. However it is not zero. In this paper I describe the work of others and myself on the question of whether dark energy density can be directly detected. This is a work-in-progress and I have no answer at present.

The “still point” cosmology

2005 ◽  
Vol 201 ◽  
pp. 514-515
Author(s):  
Ivan I. Shevchenko
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Hubble Parameter ◽  
Gravitational Constant ◽  
Critical Density ◽  
Matter Density ◽  
Future Evolution ◽  
The Future ◽  
The Universe

Recent results on supernovae as standard candles (Riess et al. 1998; Perlmutter et al. 1999) and on CMB anisotropy (Lineweaver 1998) indicate that ΩM ≍ 0.3-0.4, Ωv ≍ 0.6-0.7, ΩM + Ωv ≍ 1. By definition, ΩM = ρM/ρcr, ΩV = ρv/ρcr, where ρM is the matter density, ρv is the vacuum density; the critical density ρcr = 3H2/8πG; H is the Hubble parameter, G is the gravitational constant. In the standard Friedmann-Lemaître cosmologies, these results seriously constrain the non-dimensional cosmological constant (as defined below): Δ ≫ 1, meaning that the Universe expands forever. If a scalar field is present, the future evolution may be different.

scholarly journals RETRACTED ARTICLE: Mass–Energy Equivalence Extension onto a Superfluid Quantum Vacuum

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Amrit Srečko Šorli
Keyword(s):  
Inertial Mass ◽  
Variable Density ◽  
Quantum Vacuum ◽  
Mass Energy ◽  
Stellar Objects ◽  
Energy Equivalence ◽  
Retracted Article ◽  
Intergalactic Space ◽  
Physical Changes ◽  
The Universe

AbstractIn contemporary physics, the model of space–time as the fundamental arena of the universe is replaced by some authors with the superfluid quantum vacuum. In a vacuum, time is not a fourth dimension of space, it is merely the duration of the physical changes, i.e. motion in a vacuum. Mass–energy equivalence has its origin in the variable density of the vacuum. Inertial mass and gravitational mass are equal and both originate in the vacuum fluctuations from intergalactic space towards stellar objects.

scholarly journals Cosmological consequences of a variable cosmological constant model

2016 ◽  
Vol 26 (07) ◽  
pp. 1750060 ◽  
Author(s):  
Hemza Azri ◽  
A. Bounames
Keyword(s):  
Cosmological Constant ◽  
Vacuum Energy ◽  
Gravitational Constant ◽  
Scale Factor ◽  
Accelerated Expansion ◽  
Variable Cosmological Constant ◽  
Age Of The Universe ◽  
Two Phases ◽  
Limiting Case ◽  
The Universe

We derive a model of dark energy which evolves with time via the scale factor. The equation-of-state is studied as a function of a parameter [Formula: see text] introduced in this model as [Formula: see text]. In addition to the recent accelerated expansion, the model predicts another decelerated phase. These two phases are studied via the parameter [Formula: see text]. The age of the universe is found to be almost consistent with the observation. In the limiting case, the cosmological constant model, we find that vacuum energy gravitates with a tiny gravitational constant which evolves with the scale factor, rather than with Newton’s constant. This enables degravitation of the vacuum energy which in turn produces the tiny observed curvature, rather than a 120 orders of magnitude larger value.

scholarly journals Gravity and the Absoluteness of Time: a Simple Qualitative Model

2017 ◽  
Vol 9 (2) ◽  
pp. 42 ◽  
Author(s):  
Carmine Cataldo
Keyword(s):  
General Relativity ◽  
Single Point ◽  
Spatial Dimension ◽  
Vacuum Field ◽  
Qualitative Model ◽  
Schwarzschild Solution ◽  
Slowing Down ◽  
Gravitational Source ◽  
Dimensional Ball ◽  
The Universe

In this paper, we qualitatively examine the compatibility between gravity and the absoluteness of time. Initially, time is supposed as being absolute. However, this assumption does not imply that instruments and devices, finalized to measure time, are not influenced by gravity. On the contrary, we admit that whatever phenomenon, including the ones that occur when we measure time, shows clear traces of the influence of gravity. Nonetheless, the alleged time dilation, that seems to occur when we approach a gravitational source, could actually be illusory. In this paper, in fact, we contemplate the possibility that the above-mentioned phenomenon could be exclusively related to the contraction of the orbits induced by the mass that produces the gravitational field. We start from postulating a Universe, belonging to the oscillatory class, characterized by at least a further spatial dimension. At the beginning, the Universe in its entirety is assimilated to a four-dimensional ball, and matter is considered as being evenly spread. Once hypothesized that all the available mass may be concentrated in a single point, taking advantage of an opportune parameterization, pretending that the orbits don't undergo any modification whatsoever and admitting, as a consequence, that time starts slowing down when we move towards the singularity, we can easily obtain, far from the source, a Schwarzschild solution for the vacuum field, without using General Relativity.

scholarly journals THE VALUE OF THE COSMOLOGICAL CONSTANT

2011 ◽  
Vol 20 (14) ◽  
pp. 2875-2880 ◽  
Author(s):  
JOHN D. BARROW ◽  
DOUGLAS J. SHAW
Keyword(s):  
Wave Function ◽  
Cosmological Constant ◽  
Classical Limit ◽  
Constraint Equation ◽  
Einstein Equations ◽  
Spatial Curvature ◽  
Self Consistent ◽  
Curvature Parameter ◽  
The Universe ◽  
Planck Satellite

We make the cosmological constant, Λ, into a field and restrict the variations of the action with respect to it by causality. This creates an additional Einstein constraint equation. It restricts the solutions of the standard Einstein equations and is the requirement that the cosmological wave function possess a classical limit. When applied to the Friedmann metric it requires that the cosmological constant measured today, tU, be [Formula: see text], as observed. This is the classical value of Λ that dominates the wave function of the universe. Our new field equation determines Λ in terms of other astronomically measurable quantities. Specifically, it predicts that the spatial curvature parameter of the universe is [Formula: see text], which will be tested by Planck Satellite data. Our theory also creates a new picture of self-consistent quantum cosmological history.

scholarly journals ON THE TOPOLOGICAL NATURE OF THE COSMOLOGICAL CONSTANT

2012 ◽  
Vol 18 ◽  
pp. 109-114
Author(s):  
M. D. MAIA
Keyword(s):  
General Relativity ◽  
Cosmological Constant ◽  
Cosmic Radiation ◽  
Cosmic Time ◽  
Space Time ◽  
Time Flow ◽  
Acceleration Of The Universe ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Topological Changes

It is shown that topological changes in space-time are necessary to make General Relativity compatible with the Newtonian limit and to solve the hierarchy of the fundamental interactions. We detail how topology and topological changes appear in General Relativity and how it leaves an observable footprint in space-time. In cosmology we show that such topological observable is the cosmic radiation produced by the acceleration of the universe. The cosmological constant is a very particular case which occurs when the expansion of the universe into the vacuum occurs only in the direction of the cosmic time flow.

DELTA GRAVITY AND THE ACCELERATED EXPANSION OF THE UNIVERSE

2011 ◽  
Vol 20 (supp01) ◽  
pp. 65-72
Author(s):  
JORGE ALFARO
Keyword(s):  
General Relativity ◽  
Gravitational Field ◽  
Cosmological Constant ◽  
Equivalence Principle ◽  
Equations Of Motion ◽  
Accelerated Expansion ◽  
Symmetric Tensors ◽  
Test Particles ◽  
Expansion Of The Universe ◽  
The Universe

We study a model of the gravitational field based on two symmetric tensors. The equations of motion of test particles are derived. We explain how the Equivalence principle is recovered. Outside matter, the predictions of the model coincide exactly with General Relativity, so all classical tests are satisfied. In Cosmology, we get accelerated expansion without a cosmological constant.

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