scholarly journals Reference Level of the Vacuum Energy Density of the Universe and Astrophysical Data

2020 ◽  
Vol 68 (7) ◽  
pp. 2000047 ◽  
Author(s):  
Balakrishna S. Haridasu ◽  
Sergey L. Cherkas ◽  
Vladimir L. Kalashnikov
Keyword(s):  
Energy Density ◽  
Vacuum Energy ◽  
Reference Level ◽  
Vacuum Energy Density ◽  
Astrophysical Data ◽  
The Universe

scholarly journals Do we come from a quantum anomaly?

2019 ◽  
Vol 28 (14) ◽  
pp. 1944002 ◽  
Author(s):  
Spyros Basilakos ◽  
Nick E. Mavromatos ◽  
Joan Solà Peracaula
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Energy Density ◽  
Hubble Parameter ◽  
Vacuum Energy ◽  
Vacuum Energy Density ◽  
Quantum Anomaly ◽  
Inflationary Phase ◽  
Axion Field ◽  
The Universe

We present a string-based picture of the cosmological evolution in which (CP-violating) gravitational anomalies acting during the inflationary phase of the universe cause the vacuum energy density to “run” with the effective Hubble parameter squared, [Formula: see text], thanks to the axion field of the bosonic string multiplet. This leads to baryogenesis through leptogenesis with massive right-handed neutrinos. The generation of chiral matter after inflation helps in cancelling the anomalies in the observable radiation- and matter-dominated eras. The present era inherits the same “running vacuum” structure triggered during the inflationary time by the axion field. The current dark energy is thus predicted to be mildly dynamical, and dark matter should be made of axions. Paraphrasing Carl Sagan [ https://www.goodreads.com/author/quotes/10538.Carl_Sagan .]: we are all anomalously made from starstuff.

scholarly journals CONNECTING THE NONSINGULAR ORIGIN OF THE UNIVERSE, THE VACUUM STRUCTURE AND THE COSMOLOGICAL CONSTANT PROBLEM

2013 ◽  
Vol 22 (09) ◽  
pp. 1330018 ◽  
Author(s):  
EDUARDO I. GUENDELMAN ◽  
PEDRO LABRAÑA
Keyword(s):  
Energy Density ◽  
Scale Invariance ◽  
Vacuum Energy ◽  
Vacuum Energy Density ◽  
Emergent Universe ◽  
Vacuum Structure ◽  
Inflationary Phase ◽  
Present Universe ◽  
The Universe ◽  
Origin Of The Universe

We consider a nonsingular origin for the universe starting from an Einstein static universe, the so-called "emergent universe" scenario, in the framework of a theory which uses two volume elements [Formula: see text] and Φd4x, where Φ is a metric independent density, used as an additional measure of integration. Also curvature, curvature square terms and for scale invariance a dilaton field ϕ are considered in the action. The first-order formalism is applied. The integration of the equations of motion associated with the new measure gives rise to the spontaneous symmetry breaking (SSB) of scale invariance (SI). After SSB of SI, it is found that a nontrivial potential for the dilaton is generated. In the Einstein frame we also add a cosmological term that parametrizes the zero point fluctuations. The resulting effective potential for the dilaton contains two flat regions, for ϕ → ∞ relevant for the nonsingular origin of the universe, followed by an inflationary phase and ϕ → -∞, describing our present universe. The dynamics of the scalar field becomes nonlinear and these nonlinearities produce a nontrivial vacuum structure for the theory and are responsible for the stability of some of the emergent universe solutions, which exists for a parameter range of values of the vacuum energy in ϕ → -∞, which must be positive but not very big, avoiding the extreme fine tuning required to keep the vacuum energy density of the present universe small. The nontrivial vacuum structure is crucial to ensure the smooth transition from the emerging phase, to an inflationary phase and finally to the slowly accelerated universe now. Zero vacuum energy density for the present universe defines the threshold for the creation of the universe.

scholarly journals Application of Self-Similar Symmetry Model to Dark Energy

2018 ◽  
Author(s):  
Tomohide Sonoda
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Vacuum Energy ◽  
Structure Constant ◽  
Fine Tuning ◽  
Theoretical Modelling ◽  
Fine Structure Constant ◽  
Vacuum Energy Density ◽  
Self Similar ◽  
The Universe

Recent observations of the dark energy density demonstrates the fine-tuning problem and challenges in theoretical modelling. In this study, we apply the self-similar symmetry (SSS) model, describing the hierarchical structure of the universe based on the Dirac large numbers hypothesis, to Einstein's cosmological term. We introduce a new similarity dimension, DB, in the SSS model. Using the DB SSS model, the cosmological constant, vacuum energy density, and Hubble parameter can be simply expressed as a function of the cosmic microwave background (CMB) temperature. We show that the initial value of the vacuum energy density at the creation of the universe is ρ0 = 1/8παf6, where αf is the fine structure constant. The results indicate that the CMB is the primary factor for the evolution of the universe, providing a unified understanding of the problems of naturalness.

scholarly journals The evolution of the universe in asymmetric cosmic time

2021 ◽  
Vol 4 (3) ◽  
Keyword(s):  
Energy Density ◽  
Nuclear Force ◽  
Vacuum Energy ◽  
Cosmic Time ◽  
Big Bang ◽  
Vacuum Energy Density ◽  
De Sitter ◽  
Planck Time ◽  
The Big Bang ◽  
The Universe

The Cosmic Time Hypothesis (CTH) presented in this paper is a purely axiomatic theory. In contrast to today's standard model of cosmology, the ɅCDM model, it does not contain empirical parameters such as the cosmological constant Ʌ, nor does it contain sub-theories such as the inflation theory. The CTH was developed solely on the basis of the general theory of relativity (GRT), aiming for the greatest possible simplicity. The simplest cosmological model permitted by ART is the Einstein-de Sitter model. It is the basis for solving some of the fundamental problems of cosmology that concern us today. First of all, the most important results of the CTH: It solves one of the biggest problems of cosmology the problem of the cosmological constant (Ʌ)-by removing the relation between and the vacuum energy density ɛv (Λ=0, ɛv > 0). According to the CTH, the vacuum energy density ɛv is not negative and constant, as previously assumed, but positive and time-dependent (ɛv ̴ t -2). ɛv is part of the total energy density (Ɛ) of the universe and is contained in the energy-momentum tensor of Einstein's field equations. Cosmology is thus freed from unnecessary ballast, i.e. a free parameter (= natural constant) is omitted (Ʌ = 0). Conclusion: There is no "dark energy"! According to the CTH, the numerical value of the vacuum energy density v is smaller by a factor of ≈10-122 than the value calculated from quantum field theory and is thus consistent with observation. The measurement data obtained from observations of SNla supernovae, which suggest a currently accelerated expansion of the universe, result - if interpreted from the point of view of the CTH - in a decelerated expansion, as required by the Einstein-de Sitter universe. Dark matter could also possibly not exist, because the KZH demands that the "gravitational constant" is time-dependent and becomes larger the further the observed objects are spatially and thus also temporally distant from us. Gravitationally bound local systems, e.g. Earth - Moon or Sun - Earth, expand according to the same law as the universe. This explains why Hubble's law also applies within very small groups of galaxies, as observations show. The CTH requires that the strongest force (strong nuclear force) and the weakest (gravitational force) at Planck time (tp ≈10-43 seconds after the "big bang") when all forces of nature are supposed to have been united in a single super force, were of equal magnitude and had the same range. According to the KZH, the product of the strength and range of the gravitational force is constant, i.e. independent of time, and is identical to the product of the strength and range of the strong nuclear force. At Planck time, the universe had the size of an elementary particle (Rp = rE ≈10-15 m). This value also corresponds to the range of the strong nuclear force (Yukawa radius) and the Planck length at Planck time. The CTH provides a possible explanation for Mach's first and second principles. It solves some old problems of the big bang theory in a simple and natural way. The problem of the horizon, flatness, galaxy formation and the age of the world. The inflation theory thus becomes superfluous. • The CTH provides the theoretical basis for the theory of Earth expansion • In Cosmic Time, there was no Big Bang. The universe is infinitely old. • Unlike other cosmological models, the CTH does not require defined "initial conditions" because there was no beginning. • The CTH explains why the cosmic expansion is permanently in an unstable state of equilibrium, which is necessary for a long-term flat (Euclidean), evolutionarily developing universe.

scholarly journals Vacuum energy and the cosmological constant

2015 ◽  
Vol 30 (22) ◽  
pp. 1540033 ◽  
Author(s):  
Steven D. Bass
Keyword(s):  
Energy Density ◽  
Large Hadron Collider ◽  
Cosmological Constant ◽  
Vacuum Energy ◽  
Hadron Collider ◽  
Planck Scale ◽  
Vacuum Energy Density ◽  
Accelerating Expansion ◽  
Expansion Of The Universe ◽  
The Universe

The accelerating expansion of the Universe points to a small positive value for the cosmological constant or vacuum energy density. We discuss recent ideas that the cosmological constant plus Large Hadron Collider (LHC) results might hint at critical phenomena near the Planck scale.

scholarly journals Quantum Mechanical Explanation for Dark Energy, Cosmic Coincidence, Flatness, Age, and Size of the Universe

2019 ◽  
Vol 28 (1) ◽  
pp. 220-227 ◽  
Author(s):  
Biswaranjan Dikshit
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Vacuum Energy ◽  
Vacuum Energy Density ◽  
Quantum Mechanical ◽  
Coincidence Problem ◽  
Astronomical Observations ◽  
The Universe ◽  
Matter Energy ◽  
Cosmic Coincidence Problem

Abstract One of the most important problems in astronomy is the cosmological constant problem in which conventional calculation of vacuum energy density using quantum mechanics leads to a value which is ~10123 times more than the vacuum energy estimated from astronomical observations of expanding universe. The cosmic coincidence problem questions why matter energy density is of the same order of magnitude as the vacuum energy density at present time. Finally, the mechanism responsible for spatial flatness is not clearly understood. In this paper, by taking the vacuum as a finite and closed quantum oscillator, we solve all of the above-mentioned problems. At first, by using the purely quantum mechanical approach, we predict that the dark energy density is c4/(GR2) = 5.27×10−10 J/m3 (where R is radius of 3-sphere of the universe) and matter energy density is c4/(2GR2) = 2.6×10−10 J/m3 which match well with astronomical observations. We also prove that dark energy has always been ~66.7% and matter energy has been ~33.3% of the total energy and thus solve the cosmic coincidence problem. Next, we show how flatness of space could be maintained since the early stage of the universe. Finally, using our model, we derive the expression for age and radius of the universe which match well with the astronomical data.

scholarly journals D-Dimensional f(R,φ) Gravity

2021 ◽  
Author(s):  
Mostafa Bousder
Keyword(s):  
Energy Density ◽  
Modified Gravity ◽  
Vacuum Energy ◽  
Vacuum Energy Density ◽  
Observation Data ◽  
Einstein Field Equations ◽  
Field Equations ◽  
New Type ◽  
The Universe ◽  
Good Agreement

In this work, we explore a the different forms of a new type of modified gravity, namely f(φ) gravity. We construct the Big Rip type for the energy density and the curvature of the universe. We show that dark energy is a result of the transformation of the field φ mass (dark matter) to energy. In addition, we provide that Ω_{m}≈0,050, Ω_{DM}≈0,2, Ω_{DE}≈0,746, is in excellent agreement with observation data. We explore a generalized formalism of braneworld modified gravity. We also construct a new field equations, which generalize the Einstein field equations. We provide a relation between the extra dimension in 3-brane with the vacuum energy density. We show that the energy density of matter depends directly on the number of dimensions. We manage to find the value of the Gauss-Bonnet coupling α=1/4 which is a good agreement with the results in the literature, this correspondence creates a passage between f(R) gravity and Gauss-Bonnet gravity, this comparison leads to a number of bulk dimensions equal to D=10¹²¹+4.

scholarly journals Decaying vacuum and evolution from early inflation to late acceleration

2021 ◽  
pp. 2150160
Author(s):  
N. Sarath ◽  
Titus K. Mathew
Keyword(s):  
Energy Density ◽  
Vacuum Energy ◽  
Friedmann Equation ◽  
Time Dependent ◽  
Vacuum Energy Density ◽  
De Sitter ◽  
Unified Framework ◽  
Number Formula ◽  
Hubble Radius ◽  
The Universe

Decaying vacuum models are a class of models that incorporate a time-dependent vacuum energy density that can explain the entire evolution of the universe in a unified framework. A general solution to the Friedmann equation is obtained by considering vacuum energy density as a function of the Hubble parameter. We have obtained the asymptotic solution by choosing the equation of state for matter, [Formula: see text] and radiation, [Formula: see text]. Finite boundaries in the early and late de Sitter epoch are defined by considering the evolution of primordial perturbation wavelength. An epoch invariant number [Formula: see text] determines the number of primordial perturbation modes that cross the Hubble radius during each epoch.

scholarly journals An Alternative Approach to Estimate the Vacuum Energy Density of Free Space

2017 ◽  
Author(s):  
Vernon Cooray ◽  
Gerald Cooray ◽  
Farhad Rachidi
Keyword(s):  
Energy Density ◽  
Particle Physics ◽  
Vacuum Energy ◽  
Empty Space ◽  
Negative Energy ◽  
Accelerated Expansion ◽  
Vacuum Energy Density ◽  
Net Energy ◽  
Planck Time ◽  
The Universe

According to the current understanding, the recently observed   accelerated expansion of the universe is caused by the dark or the vacuum energy. Attempts to calculate the magnitude of this energy using the standard model of particle physics led to values which are 59 – 120 orders of magnitude larger than the experimentally estimated one. Even though the expanding space has positive internal energy, in a flat universe it is completely balanced by the negative energy of gravitational field making the net energy equal to zero. However, the current physical theories may breakdown for times less than or on the order of Planck time and one cannot assume that the above assertion concerning the balance of two energies is valid also in this time scale. In this note it is assumed that this balance of the two energies during the creation of new space as the universe expands takes place only for times larger than the Planck time. If this assumption is correct, the net energy of the newly created space remains positive for times on the order of Planck time and the positive vacuum energy has to be burrowed from empty space before it is being balanced by gravity. This can happen only within the restrictions of the time-energy uncertainty principle. In this note it is shown that such considerations lead to a vacuum energy density of about 0.3 Nanojoules per cubic meter which has to be compared with the measured value of 0.6 Nanojoules per cubic meter.

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