Amount Of Dark Energy Research Articles

The dark matter and dark energy

The dark matter and dark energy are one of the biggest challenges facing contemporary physics and astronomy. Dark energy and dark matter play an important role the universe. The amount of dark energy and dark matter determines how the universe changes. When there’s more dark energy, the universe is accelerating. If there were more dark matter, the universe might slow down, or even stop expanding and start contracting. So in this paper, the basic definition of dark matter and dark energy are introduced. And how were dark matter and dark energy discovered and their respective detection methods and the current progress of experiments to detect dark matter and dark energy respectively.

Experiment with a laser and a mirror to accurately measure the Hubble constant

We propose a new method for calculating the redshift in galaxies, according to which the amount of redshift in the spectrum of each galaxy consists of two parts: about 2/3 of the redshift is due to the speed of the galaxy moving away from us, and about 1/3 is due to the fact that photons moving in the expanding Universe acquire an additional (non-Doppler) redshift. The additional reddening of photons in the spectrum of the galaxy is due to photons coming to us from the past, when the gravitational potential of the universe was lower, and consequently, the frequencies of atomic spectra were also lower than at present. A scheme of a laboratory experiment is proposed that will allow direct measurement of a non-Doppler (additional) part of the cosmological redshift and demonstrate the very fact of the expansion of the universe in real time in about 15 min. The experiment also makes it possible to measure the expansion rate of the universe and its current gravitational potential. These results will help to significantly refine modern ideas about the age of the universe, and about the amount of dark energy and dark matter in it.

Bifurcated symmetry breaking in scalar-tensor gravity

We present models that simultaneously predict the presence of dark energy and cold dark matter along with slow-roll inflation. The dark energy density is found to be of order $(\text{a few meV}{)}^{4}$, and the mass of dark matter constituent is $\ensuremath{\approx}1\text{ }\text{ }\mathrm{meV}$. These numbers are given in terms of the present value of Hubble constant ${H}_{0}$ and the Plank energy ${M}_{\mathrm{P}}\text{ }=\text{ }1/\sqrt{16\ensuremath{\pi}{G}_{N}}$: they are $({H}_{0}{M}_{\mathrm{P}}{)}^{2}$ for the dark energy density and $({H}_{0}{M}_{\mathrm{P}}{)}^{1/2}$ for the dark matter constituent mass. The basic theoretical framework we work in is a multiscalar tensor gravity with nontrivial conformal coupling to the Ricci scalar curvature in the Lagrangian density. The key for a right amount of dark energy is to incorporate in a novel way the spatially homogeneous kinetic contribution of Nambu-Goldstone modes in a spontaneously broken multiscalar field sector. Proposed theories are made consistent with general relativity tests at small cosmological distances, yet are different from general relativity at cosmological scales. Dark matter is generated as a spatially inhomogeneous component of the scalar system, with a roughly comparable amount to the dark energy. In some presented models a cosmological bifurcation of symmetry breaking of the scalar sector is triggered by the spontaneous breaking of electroweak $\mathrm{SU}(2)\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1)$ gauge symmetry, hence the separation occurring simultaneously at the electroweak phase transition. The best experimental method to test presented models is to search for the fifth-force type of scalar exchange interaction with a force range, $O({10}^{\ensuremath{-}2})\text{ }\text{ }\mathrm{cm}$, whose coupling to matter is basically of gravitational strength.

Multi-Bubble Universe Model: A Quantum-Relativistic Gravitational Theory of Space-Time

A multi-bubble model of universe is presented, in which gravity is the result of the aging of electromagnetic dipoles produced in quantum fluctuations of the action inside a condensate of a particular type of balancing gravitons. In the model, the exchange of gravitons among the dipoles and the potential of vacuum balances the energy of the fluctuation. The effect is to create bubbles of space-time that by growing they expand the local vacuum. The model suggests that the universe originates from overlapping of bubbles of space-time associated with dipoles. Matter is originated during gravitons decay. The use of the Bridge Theory demonstrates how the attractive force field that emerges in each bubble is in the first approximation in accordance with Newtonian gravity at small, medium and large distances in accordance with the theory of General Relativity by also introducing a variable cosmological term that justifies some observed cosmological anomalies. The model overcomes the current concepts of Dark Energy and Dark Mass in favor of a gravity produced by the curvature of space-time of the bubble. The existence of the balancing gravitons provides an estimate of the actual amounts of Dark Energy, Dark Matter and matter measured in the current universe. The estimated theoretical mass of the balancing gravitons is consistent with the Kaluza-Klein gravitons of 2.68 TeV observed in the ATLAS experiment during Run #1. Moreover, the use of the observational data of the rotation speeds of two samples of galaxies allows to verify the good agreement of the real universe with the model, providing a possible explanation of the variability in the measurement of the Hubble constant.

Dark energy as the information field of the universe

Using modern theories of the origin and expansion of the Universe, recent discoveries in astronomy and quantum physics, the article proposes the hypothesis to add to attributes of the nascent universe such as “space” and “time” of the attribute “information,” which finds its embodiment from a physical point of view in the form dark energy. With the development of the Universe, the volume of information grows and, accordingly, the mass of dark energy increases, turning into an information field or noosphere, which provides for the expansion of the Universe. An analogy is made between the Big Bang and the expansion of the Universe in the process of its evolution, due to the increase in the amount of dark energy and between the birth of Man from singularity (egg) and the growth of his information and knowledge in the process of his life.

Constraints on the spacetime dynamics of an early dark energy component

We consider an Early Dark Energy (EDE) cosmological model, and perform an analysis which takes into account both background and perturbation effects via the parameters c2eff and c2vis, representing effective sound speed and viscosity, respectively. By using the latest available data we derive constraints on the amount of dark energy at early times and the present value of the equation of state. Our focus is on the effect that early dark energy has on the Cosmic Microwave Background (CMB) data, including polarization and lensing, in a generalized parameter space including a varying total neutrino mass, and tensor to scalar ratio, besides the 6 standard parameters of the minimal cosmological model. We find that the inclusion of Baryonic Acoustic Oscillations (BAO) data and CMB lensing significantly improves the constraints on the EDE parameters, while other high redshift data like the Quasar Hubble diagram and the Lyman-α forest BAO have instead a negligible impact. We find ΩeDE < 0.0039 and w0 < −0.95 at the 95 % C.L. for EDE accounting for its clustering through the inclusion of perturbation dynamics. This limit becomes weaker ΩeDE < 0.0034 if perturbations are neglected. The constraints on the EDE parameters are remarkably stable even when Σ mν, and r parameters are varied, with weak degeneracies between ΩeDE and r or Σ mν. In general we expect smaller values for the upper limits on the total amount of EDE with an increasing neutrino mass, while with a decreasing value of the tensor to scalar ratio we expect the 2σ upper limits on EDE to increase. We compare this EDE model with a simple wCDM with zero dark energy at early times and we find ∼1–2% different upper limits on total neutrino mass and ∼0.1–0.2% difference on the equation of state at the present time. Perturbation parameters are not constrained with current data sets, and tensions between the CMB derived H0 and σ8 values and those measured with local probes are not eased. This work demonstrates the capability of CMB probes to constrain the total amount of EDE well below the percent level.

Ten Arguments Against the Proclaimed Amount of Dark Matter

According to the Standard cosmological model, our universe needs a significant amount of dark matter (DM), about six times that of the usual baryonic matter, besides an even larger amount of dark energy. But to date, both DMand dark energy have remained conceptually delusive, without concrete evidence based on direct physical measurements. In this survey paper, we present ten counterarguments showing that such a claimed amount of DMcan be a result of vast overestimation and does not conform to reality. Some of those counterarguments can be convincingly verified even by simple hand calculations.

Physical theories in the context of multiverse

The article analyzes the problem of physical theory nature and its criteria in the context of several concepts of modern physics. Such physical concepts allow multiple possible universes (the last usually happens to be a random consequence of the theory). Since the study requires several universe models, which basic principles (physical laws) can vary, the two theories have become the objects of analysis: the first, which includes the concept of eternal inflation, the second – the string cosmology (the string landscape). Both theories allow for a large variation of physical laws (no matter, whether these are fundamentally different physical laws or different versions of the same basic principles). The amount of dark energy (cosmological constant) has been selected as a physical law parameter, changing its value in possible universes. The analysis of the physical theories, which allow a multiplicity of universes, has shown that the standard requirements for the theory, which connect its veracity with the criteria of observability and the need for validation of our universe basic principles, are not entirely consistent. Theoretical physics is moving towards the formulization of models that become a real (in some cases, apparently irresistible) challenge for experimental verification. The article proves that such verification probably can not be required in several physical theories, since, in particular, the postulation of this kind of connection between theory and reality is no more than a manifestation of anthropocentrism. The theory can also register some more common grounds, which lie beyond the scope of observation

Physics Theories in the Context of Multiverse

The article analyzes the problem of physical theory nature and its criteria in the context of several concepts of modern physics. Such physical concepts allow multiple possible universes (the last usually happens to be a random consequence of the theory). Since the study requires several universe models, which basic principles (physical laws) can vary, the two theories have become the objects of analysis: the first, which includes the concept of eternal inflation, the second – the string cosmology (the string landscape). Both theories allow for a large variation of physical laws (no matter, whether these are fundamentally different physical laws or different versions of the same basic principles). The amount of dark energy (cosmological constant) has been selected as a physical law parameter, changing its value in possible universes. The analysis of the physical theories, which allow a multiplicity of universes, has shown that the standard requirements for the theory, which connect its veracity with the criteria of observability and the need for validation of our universe basic principles, are not entirely consistent. Theoretical physics is moving towards the formulization of models that become a real (in some cases, apparently irresistible) challenge for experimental verification. The article proves that such verification probably can not be required in several physical theories, since, in particular, the postulation of this kind of connection between theory and reality is no more than a manifestation of anthropocentrism. The theory can also register some more common grounds, which lie beyond the scope of observation.

Probing the frontiers of particle physics with tabletop-scale experiments.

The field of particle physics is in a peculiar state. The standard model of particle theory successfully describes every fundamental particle and force observed in laboratories, yet fails to explain properties of the universe such as the existence of dark matter, the amount of dark energy, and the preponderance of matter over antimatter. Huge experiments, of increasing scale and cost, continue to search for new particles and forces that might explain these phenomena. However, these frontiers also are explored in certain smaller, laboratory-scale "tabletop" experiments. This approach uses precision measurement techniques and devices from atomic, quantum, and condensed-matter physics to detect tiny signals due to new particles or forces. Discoveries in fundamental physics may well come first from small-scale experiments of this type.

Emergent Universe as an interaction in the dark sector

A cosmological scenario where dark matter interacts with a variable vacuum energy for a spatially flat Friedmann–Robertson–Walker (FRW) spacetime is proposed and analyzed to show that with a linear equation of state and a particular interaction in the dark sector it is possible to get a model of an Emergent Universe. In addition, the viability of two particular models is studied by taking into account the recent observations. The updated observational Hubble data and the JLA supernovae data are used in order to constraint the cosmological parameters of the models and estimate the amount of dark energy in the radiation era. It is shown that the two models fulfil the severe bounds of [Formula: see text] at the 2[Formula: see text] level of Planck.

Survey finds galaxy clumps stirred up by dark energy.

The biggest study so far of the large-scale structure of the universe—a survey of 26 million galaxies that traced the forces shaping the universe over cosmic time—reveals the effects of dark energy, the mysterious pressure causing space to expand faster and faster. The survey finds about the same total amount of dark energy as the gold standard in assessing this cosmic recipe: precision maps of the nearly 14-billion-year-old cosmic microwave background that forms the backdrop of the universe. But the new survey and other techniques are now allowing astronomers to watch how dark energy plays out over time. Their goal: to see whether it changes.

Observational constraints from supernovae Ia and gamma-ray bursts on a clumpy universe

The luminosity distance describing the effect of local inhomogeneities in the propagation of light proposed by Zeldovich, Kantowski, Dyer, and Roeder is tested with two probes for two distinct ranges of redshifts: supernovae Ia in $0.015\ensuremath{\le}z\ensuremath{\le}1.414$ and gamma-ray bursts in $1.547\ensuremath{\le}z\ensuremath{\le}3.57$. Our analysis is performed by a Markov chain Monte Carlo code that allows us to constrain the matter density parameter ${\ensuremath{\Omega}}_{m}$ as well as the smoothness parameter $\ensuremath{\alpha}$ that measures the inhomogeneous-homogeneous rate of the cosmic fluid in a flat $\ensuremath{\Lambda}$ cold dark matter model. The obtained best fits are ${\ensuremath{\Omega}}_{m}={0.285}_{\ensuremath{-}0.018}^{+0.019}$, $\ensuremath{\alpha}={0.856}_{\ensuremath{-}0.176}^{+0.106}$ from supernovae Ia, and ${\ensuremath{\Omega}}_{m}={0.259}_{\ensuremath{-}0.028}^{+0.028}$, $\ensuremath{\alpha}={0.587}_{\ensuremath{-}0.202}^{+0.201}$ from gamma-ray bursts, while from the joint analysis the best fits are ${\ensuremath{\Omega}}_{m}={0.284}_{\ensuremath{-}0.020}^{+0.021}$, $\ensuremath{\alpha}={0.685}_{\ensuremath{-}0.171}^{+0.164}$ with ${\ensuremath{\chi}}_{\mathrm{red}}^{2}=0.975$. The value of the smoothness parameter $\ensuremath{\alpha}$ indicates a clumped universe; however, it does not have an impact on the amount of dark energy (cosmological constant) needed to fit the observations. This result may be an indication that the Dyer-Roeder approximation does not describe in a precise form the effects of clumpiness in the expansion of the Universe.

Modified holographic Ricci dark energy coupled to interacting dark matter and a non-interacting baryonic component

We examine a Friedmann-Robertson-Walker universe filled with interacting dark matter, modified holographic Ricci dark energy (MHRDE), and a decoupled baryonic component.The estimations of the cosmic parameters with Hubble data lead to an age of the universe of $13.17 {\rm Gyr}$ and show that the MHRDE is free from the cosmic-age problem at low redshift ($0 \leq z \leq 2$) in contrast to holographic Ricci dark energy (HRDE) case. We constrain the parameters with the Union2 data set and contrast with the Hubble data. We also study the behavior of dark energy at early times by taking into account the severe bounds found at recombination era and/or at big bang nucleosynthesis. The inclusion of a non interacting baryonic matter forces that the amount of dark energy at $z_{t} \sim {\cal O}(1)$ changes abruptly implying that $\Omega_x (z\simeq 1100) =0.03$, so the bounds reported by the forecast of Planck and CMBPol experiments are more favored for the MHRDE model than in the case of HRDE cutoff. For the former model, we also obtain that at high redshift the fraction of dark energy varies from 0.006 to 0.002, then the amount of $\Omega_x $ at the big bang nucleosynthesis era does not disturb the observed Helium abundance in the universe provided that the bound $\Omega_{x}(z\simeq 10^{10})<0.21$ is hold.

Possible dark energy imprints in the gravitational wave spectrum of mixed neutron-dark-energy stars

In the present paper we study the oscillation spectrum of neutron stars containing both ordinary matter and dark energy in different proportions. Within the model we consider, the equilibrium configurations are numerically constructed and the results show that the properties of the mixed neuron-dark-energy star can differ significantly when the amount of dark energy in the stars is varied. The oscillations of the mixed neuron-dark-energy stars are studied in the Cowling approximation. As a result we find that the frequencies of the fundamental mode and the higher overtones are strongly affected by the dark energy content. This can be used in the future to detect the presence of dark energy in the neutron stars and to constrain the dark-energy models.

A cosmological exact solution of generalized Brans-Dicke theory with complex scalar field and its phenomenological implications

Abstract When the Brans-Dicke theory is formulated in terms of the Jordan scalar field φ, the amount of dark energy is related to the mass of this field. We investigate a solution which is relevant to the late universe. We show that if φ is taken to be a complex scalar field, then an exact solution to the vacuum equations requires that the Friedmann equation possesses both a constant term and one which is proportional to the inverse sixth power of the scale factor. Possible interpretations and phenomenological implications of this result are discussed.

Deformation of Two Coupled Scalar Fields with Cosmological Solution

We know that the cosmic acceleration in modern cosmology are discussed in Refs. [1–3]. The amount of dark energy is almost 70% of total energy of the universe. This energy causes the present cosmic acceleration. The dark energy is a hypothetical form of energy which permeates the whole space and tends to increase rate of expansion of the universe. The existence of dark energy is the most popular way to explain recent observations that the universe appears to be expanding at an accelerating rate. The standard Friedman–Robertson–Walker (FRW) model with the real scalar fields can be a candidate to describe the dark energy. Also the presence of acceleration in cosmology leads us to consider scalar fields. In order to investigate the rate of expansion we obtain first-order differential equation which solves the corresponding equation of motion. Evidently, the presence of first-order equation eases the process of solving specific models and also can be used to fully understand the related cosmic evolution. The key motivation for the present work has appeared after the work [4] which deals with FRW cosmology driven by real scalar field. As we know, if the scale factor a(t) is known, the potential V (t) and ∗corresponding author; e-mail: pouriya@ipm.ir

Measurement of Gravitomagnetic and Acceleration Fields Around Rotating Superconductors

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Cosmological constant from gauge fields on extra dimensions

Abstract We present a new model of dark energy which could explain the observed accelerated expansion of our Universe. We show that a five-dimensional Einstein–Yang–Mills theory defined in a flat Friedmann–Robertson–Walker universe compactified on a circle possesses degenerate vacua in four dimensions. The present Universe could be trapped in one of these degenerate vacua. With the natural requirement that the size of the extra dimension could be of the GUT scale or smaller, the energy density difference between the degenerate vacua and the true ground state can provide us with just the right amount of dark energy to account for the observed expansion rate of our Universe.

A PARAMETRIZED VARIABLE DARK ENERGY MODEL: STRUCTURE FORMATION AND OBSERVATIONAL CONSTRAINTS

In this paper we investigate a simple parametrization scheme of the quintessence model given by Wetterich [Phys. Lett. B594, 17 (2004)]. The crucial parameter of this model is the bending parameter b, which is related to the amount of dark energy in the early universe. Using the linear perturbation and the spherical infall approximations, we investigate the evolution of matter density perturbations in the variable dark energy model, and obtain an analytical expression for the growth index f. We show that increasing b leads to less growth of the density contrast δ, and also decreases the growth index. Giving a fitting formula for the growth index at the present time, we verify that the approximation relation [Formula: see text] also holds in this model. To compare predictions of the model with observations, we use the Supernovae type Ia (SNIa) Gold Sample and the parameters of the large scale structure determined by the 2-degree Field Galaxy Redshift Survey (2dFGRS). The best fit values for the model parameters by marginalizing on the remained ones, are [Formula: see text], [Formula: see text] and [Formula: see text] at 1σ confidence level. As a final test we calculate the age of universe for different choices of the free parameters in this model and compare it with the age of old stars and some high redshift objects. Then we show that the predictions of this variable dark energy model are consistent with the age observation of old star and can solve the "age crisis" problem.