Cosmological Vacuum Research Articles

From de Sitter to de Sitter: A Thermal Approach to Running Vacuum Cosmology and the Non-Canonical Scalar Field Description

The entire classical cosmological history between two extreme de Sitter vacuum solutions is discussed based on Einstein’s equations and non-equilibrium thermodynamics. The initial non-singular de Sitter state is characterised by a very high energy scale, which is equal or smaller than the reduced Planck mass. It is structurally unstable, and all of the continuous created matter, energy, and entropy of the material component comes from the irreversible flow powered by the primeval vacuum energy density. The analytical expression describing the running vacuum is obtained from the thermal approach. It opens a new perspective to solve the old puzzles and current observational challenges plaguing the cosmic concordance model driven by a rigid vacuum. Such a scenario is also modelled through a non-canonical scalar field. It is demonstrated that the resulting scalar field model is shown to be a step-by-step a faithful analytical representation of the thermal running vacuum cosmology.

Cosmological first-order vacuum phase transitions in an expanding anisotropic universe

We examine the anisotropy originated from a first-order vacuum phase transitions through three-dimensional numerical simulations. We apply Bianchi Type-I metric to our model that has one scalar field minimally coupled to the gravity. We calculate the time evolution of the energy density for the shear scalar and the directional Hubble parameters as well as the power spectra for the scalar field and the gravitational radiation although there are a number of caveats for the tensor perturbations in Bianchi Type-I universe. We run simulations with different mass scales of the scalar field, therefore, in addition to investigation of anisotropy via the shear scalar, we also determine at which mass scale the phase transition completes successfully, hence, neglecting the expansion of the Universe does not significantly affect the results. Finally, we showed that such an event may contribute to the total anisotropy depending on the mass scale of the scalar field and the initial population of nucleated bubbles.

ASKING IF VACUUM ENERGY allows COMPUTATIONAL “BITS” PRESENT AT START OF COSMOLOGICAL EVOLUTION, and its possible ties into torsion physics

Based on Torsion as given by de Sabbata and Sirvaram, Erice 1990 . The 1990 article claims that Torsion cancels Cosmological vacuum energy. We consider if relic black holes at the start of inflation may allow for the observed cosmological constant. Using the 1990 text if thermal energy is used at start of inflation creates conceptual issues, whereas an energy term based on Corda’s treatment of black holes may provide a solution. i.e. a left over cosmological constant 10^-121 times vacuum energy . Considerations as to how black hole physics may contribute to torsion and the cosmological constant are considered in several numerical cases Also we present entanglement entropy in the early universe with a shrinking scale factor, due to Muller and Lousto , and show that there are consequences due to initial entanged for a time dependent horizon radius in cosmology, with (flat space conditions) for conformal time . This construction preserves a minimum non zero vacuum energy, and in doing so keep the bits, for computational bits cosmological evolution. The bits are ascribed to initial torsion for reasons which we elaborate on in this manuscript

The latest achievements of fundamental physics as a tool of “culture shock” in education

Specific topics from the field of the latest fundamental physics are proposed for their implementation in the educational process. It is proved that the considered ideas of elementary particle physics and cosmology contain stunning images. These are modern ideas about the structure of the Universe, about dark energy (cosmological vacuum), and the program for building a unified field theory, and the concept of a non-local observer in general relativity; and the accelerated expansion of the Universe with the Big Rip tendency of a Big Gap, and the geometrodynamic concept, and the multidimensional space-time of our Universe, and the superstring model, and the concept of spontaneous symmetry breaking of the cosmological vacuum. And finally, the anthropic principle. Their summary is given. These problems inevitably contribute to the formation of an association of surprise and surprise among students, which is a strong argument in favor of using shock pedagogy technologies. It is proved that the discussed issues serve the spiritual and moral enrichment of young people and the formation of personally significant qualities of their characters in contrast to the routine and moralistic attitudes traditionally used in the educational process. The question is raised about the need to allocate additional hours in the scope of the discipline “Physics” for students of natural science and engineering areas of training / specialties and to restore the status of the discipline “Concepts of modern natural science” for students of humanities / specialties.

The role of gravity in naturalness versus consistency: strong- CP and dark energy

There is an ongoing debate on how seriously one should take the naturalness puzzles as the guidelines to new physics. In this debate gravity is often put aside, as an insignificant spectator force. However, this attitude misses the entire essence of the story. Through its S -matrix formulation, gravity promotes certain puzzles, such as the cosmological constant and strong- C P problems, into the consistency issues. The respective consistency requirements make the theory highly predictive. In particular, the cosmological vacuum energy must be zero. This has fundamental implications both for strong- C P and for dark energy puzzles. QCD must include an axion as an intrinsic part of the gauge redundancy, without the need of any global symmetry. This gives ϑ ¯ = 0 to all orders in operator expansion. Applied to cosmology, the S -matrix implies that the energy budget of the Universe cannot come from a constant. Correspondingly, the dark energy is an unambiguous signal of new physics around the Hubble scale. This article is part of the theme issue ‘The particle-gravity frontier’.

Vacuum Energy, the Casimir Effect, and Newton’s Non-Constant

The idea of quantum mechanical vacuum energy contributing to the cosmological vacuum energy density is not new. However, despite the persisting cosmological constant problem, few investigations have focused on this subject. We explore the possibility that the quantum vacuum energy density contributes to the (local) gravitational energy density in the framework of a scale-dependent cosmological constant Λ and Newton’s constant G. This hypothesis has several important consequences, ranging from quantum scale-dependence to the hypothetical prospect of novel experimental insight concerning the quantum origin of cosmological energy density.

Running vacuum cosmology with bulk viscous matter

In this paper, we study the late accelerating expansion of the universe by incorporating bulk viscous matter with the running vacuum. The running vacuum is assumed to be varied as the square of the Hubble parameter ([Formula: see text]), while the coefficient of bulk viscosity of matter is taken to be proportional to the Hubble parameter ([Formula: see text]). We have analytically solved for the Hubble parameter and estimated the model parameters using the combined data set [Formula: see text]. The evolution of the cosmological parameters was analyzed, and the universe’s age is estimated to be 13.94[Formula: see text]Gyr. The evolution of the universe in the present model marked considerable improvement compared to bulk viscous matter-dominated models. The transition from matter-dominated decelerated phase to vacuum energy-dominated accelerating phase occurred at a transition redshift, [Formula: see text], and the evolution asymptotically approaches a de Sitter epoch. We have obtained the coefficient of bulk viscosity of the matter component as [Formula: see text] which is two orders of magnitude less than the value predicted by most of the bulk viscous matter-dominated models. The statefinder analysis distinguishes our model from the [Formula: see text]CDM model at present, and the [Formula: see text] trajectory reveals the quintessence behavior of the vacuum energy. The model was found to satisfy the generalized second law of thermodynamics, and the entropy is maximized in the far future evolution.

Quantum trans-Planckian physics inside black holes and its spectrum

We provide a quantum unifying picture for black holes of all masses and their main properties covering classical, semiclassical, Planckian, and trans-Planckian gravity domains: space-time, size, mass, vacuum (``zero-point'') energy, temperature, partition function, density of states, and entropy. Novel results of this paper are that black hole interiors are always quantum, trans-Planckian, and of constant curvature. This is so for all black holes, including the most macroscopic and astrophysical ones. The black hole interior trans-Planckian vacuum is similar to the earliest cosmological vacuum, where the classical gravity dual is the low energy gravity vacuum---today, dark energy. There is no singularity boundary at $r=0$; the quantum space-time is regular. We display the quantum Penrose diagram of the Schwarzschild-Kruskal black hole. The complete black hole instanton (imaginary time) covers the known classical Gibbons-Hawking instanton plus a new, central, highly dense quantum core of Planck length radius and constant curvature. The complete partition function, entropy, temperature, decay rate, discrete levels, and density of states all include the trans-Planckian domain. The semiclassical black hole entropy (the Bekenstein-Hawking entropy) $(\sqrt{n}{)}^{2}$ ``interpolates'' between the quantum point particle entropy ($n$) and the quantum string entropy $\sqrt{n}$, while the quantum trans-Planckian entropy is $1/(\sqrt{n}{)}^{2}$. Black hole evaporation finishes in a pure (nonmixed) quantum state of particles, gravitons, and radiation.

Dark Energy Is the Cosmological Quantum Vacuum Energy of Light Particles—The Axion and the Lightest Neutrino

We uncover the general mechanism and the nature of today’s dark energy (DE). This is only based on well-known quantum physics and cosmology. We show that the observed DE today originates from the cosmological quantum vacuum of light particles, which provides a continuous energy distribution able to reproduce the data. Bosons give positive contributions to the DE, while fermions yield negative contributions. As usual in field theory, ultraviolet divergences are subtracted from the physical quantities. The subtractions respect the symmetries of the theory, and we normalize the physical quantities to be zero for the Minkowski vacuum. The resulting finite contributions to the energy density and the pressure from the quantum vacuum grow as loga(t), where a(t) is the scale factor, while the particle contributions dilute as 1/a3(t), as it must be for massive particles. We find the explicit dark energy equation of state of today to be P=w(z)H: it turns to be slightly w(z)<−1 with w(z) asymptotically reaching the value −1 from below. A scalar particle can produce the observed dark energy through its quantum cosmological vacuum provided that (i) its mass is of the order of 10−3 eV = 1 meV, (ii) it is very weakly coupled, and (iii) it is stable on the time scale of the age of the universe. The axion vacuum thus appears as a natural candidate. The neutrino vacuum (especially the lightest mass eigenstate) can give negative contributions to the dark energy. We find that w(z=0) is slightly below −1 by an amount ranging from (−1.5×10−3) to (−8×10−3) and we predict the axion mass to be in the range between 4 and 5 meV. We find that the universe will expand in the future faster than the de Sitter universe as an exponential in the square of the cosmic time. Dark energy today arises from the quantum vacuum of light particles in FRW cosmological space-time in an analogous way to the Casimir vacuum effect of quantum fields in Minkowski space-time with non-trivial boundary conditions.

Solving the Problem of the Cosmological Constant and Vacuum Energy Density by Considering the Cosmic Quantum Number

Solving the Problem of the Cosmological Constant and Vacuum Energy Density by Considering the Cosmic Quantum Number

Nearly Forgotten Cosmological Concept of E. B. Gliner

E. B. Gliner started his scientific career in 1963 at the age of 40. In 1965, when the existence of the cosmological constant λ seemed unnecessary to most cosmologists, he renewed interest in the problem by emphasizing a material interpretation of de Sitter space (i.e., the space curved in the presence of λ). According to that interpretation, the curvature is produced by a cosmological vacuum (now identified as dark energy of the universe). In 1970, Gliner proposed a description of exponential expansion (or contraction) of the universe at the early (or late) evolution stage dominated by cosmological vacuum. In 1975, Gliner (with I. G. Dyminikova) suggested a model of the early universe free of Big Bang singularity, and developed a scenario of nonsingular Friedmann cosmology. Many of these findings were used in the modern inflation scenarios of the universe, first proposed by A. A. Starobinsky (1979) and A. Guth (1981) and greatly multiplied later. However, these inflation scenarios differ from the scenario of Gliner and Dymnikova, and Gliner’s contribution to cosmology is nearly forgotten. The history and the essence of this contribution are outlined, as well the difference from the inflation theories.

Cosmological Inconstant, Supernovae 1a and Decelerating Expansion

In 1998, two groups of astronomers, one led by Saul Perlmutter and the other by Brian Schmidt, set out to determine the deceleration—and hence the total mass/energy—of the universe by measuring the recession speeds of type la supernovae (SN1a), came to an unexpected conclusion: ever since the universe was about 7 billion years old, its expansion rate has not been decelerating. Instead, the expansion rate has been speeding up. To justify this acceleration, they suggested that the universe does have a mysterious dark energy and they have emerged from oblivion the cosmological constant, positive this time, which is consistent with the image of an inflationary universe. To explain the observed dimming of high-redshift SN1a they have bet essentially on their distance revised upwards. We consider that an accelerated expansion leads right to a “dark energy catastrophe” (i.e., the chasm between the current cosmological vacuum density value of 10 GeV/m3 and the vacuum energy density proposed by quantum field theory of ~10122 GeV/m3). We suppose rather that the universe knows a slowdown expansion under the positive pressure of a dark energy, otherwise called a variable cosmological constant. The dark luminosity of the latter would be that of a “tired light” which has lost energy with distance. As for the low brilliance of SN1a, it is explained by two physical processes: The first relates to their intrinsic brightness—supposedly do not vary over time—which would depend on the chemical conditions which change with the temporal evolution; the second would concern their apparent luminosity. Besides the serious arguments already known, we strongly propose that their luminosity continually fades by interactions with cosmic magnetic fields, like the earthly PVLAS experiment which loses much more laser photons than expected by crossing a magnetic field. It goes in the sense of a “tired light” which has lost energy with distance, and therefore, a decelerated expansion of the universe. Moreover, we propose the “centrist” principle to complete the hypothesis of the cosmological principle of homogeneity and isotropy considered verified. Without denying the Copernican principle, he is opposed to a “spatial” theoretical construction which accelerates the world towards infinity. The centrist principle gives a “temporal” and privileged vision which tends to demonstrate the deceleration of expansion.

Cosmological constant and vacuum zero point energy in black hole backgrounds

We study the quantum vacuum zero point energy in the Schwarzschild black hole as well as in the Nariai limit of the dS-Schwarzschild backgrounds. We show that the regularized vacuum energy density near the black hole and also in the Nariai setup match exactly with the corresponding value in the flat background, scaling with the fourth power of the mass of the quantum field. The horizon radius of the dS space created from the vacuum zero point energy introduces a new length scale which should be compared with the black hole horizon radius. There is an upper limiting mass for the black hole immersed in the vacuum zero point energy which is determined by the mass of the Nariai metric associated to the dS background constructed from zero point energy. We calculate the variance in the distribution of the vacuum zero point energy and the density contrast and show that it develops strong inhomogeneities on sub-horizon scales.

Closed conformal Killing–Yano initial data

Through an exhaustive search, we produce a five-parameter family of propagation identities for the closed conformal Killing–Yano (cCYK) equation on two-forms, which hold on an Einstein cosmological vacuum spacetime in any dimension n > 4. It is well-known that spacetimes admitting a non-degenerate two-form of this type are exhausted by the Kerr-NUT-(A)dS family of exact higher dimensional black hole solutions. As a consequence, we identify a set of necessary and sufficient conditions ensuring that the cosmological vacuum development of an initial data set for Einstein’s field equations admits a cCYK two-form. We refer to these conditions as closed conformal Killing–Yano initial data equations. The four-dimensional case is special and is treated separately, where we can also handle the conformal Killing–Yano equation without the closed condition.

Shan–Chen interacting vacuum cosmology

ABSTRACT In this paper, we introduce a novel class of interacting vacuum models, based on recasting the equation of state originally developed in the context of lattice kinetic theory by Shan & Chen as the coupling between the vacuum and cold dark matter (CDM). This coupling allows the vacuum to evolve and is non-linear around a characteristic energy scale ρ*, changing into a linear coupling with a typical power-law evolution at scales much lower and much higher than ρ*. Focusing on the simplest sub-class of models where the interaction consists only of an energy exchange and the CDM remains geodesic, we first illustrate the various possible models that can arise from the Shan–Chen coupling, with several different behaviours at both early and late times depending on the values of the model parameters selected. We then place the first observational constraints on this Shan–Chen interacting vacuum scenario, performing an MCMC analysis to find those values of the model and cosmological parameters which are favoured by observational data. We focus on models where the non-linearity of the coupling is relevant at late times, choosing for the reference energy scale ρ*, the critical energy density in ΛCDM. We show that the observational data we use are compatible with a wide range of models which result in different cosmologies. However, we also show that ΛCDM is preferred over all of the Shan–Chen interacting vacuum models that we study, and comment on the inability of these models to relax the H0 and σ8 tensions.

No-lose theorem for discovering the new physics of (g−2)μ at muon colliders

We perform a model-exhaustive analysis of all possible beyond Standard Model (BSM) solutions to the $(g-2)_\mu$ anomaly to study production of the associated new states at future muon colliders, and formulate a no-lose theorem for the discovery of new physics if the anomaly is confirmed and weakly coupled solutions below the GeV scale are excluded. Our goal is to find the highest possible mass scale of new physics subject only to perturbative unitarity, and optionally the requirements of minimum flavour violation (MFV) and/or naturalness. We prove that a 3 TeV muon collider is guaranteed to discover all BSM scenarios in which $\Delta a_\mu$ is generated by SM singlets with masses above $\sim $ GeV; lighter singlets will be discovered by upcoming low-energy experiments. If new states with electroweak quantum numbers contribute to $(g-2)_\mu$, the minimal requirements of perturbative unitarity guarantee new charged states below $\mathcal{O}(100 {\rm TeV})$, but this is strongly disfavoured by stringent constraints on charged lepton flavour violating (CLFV) decays. Reasonable BSM theories that satisfy CLFV bounds by obeying Minimal Flavour Violation (MFV) and avoid generating two new hierarchy problems require the existence of at least one new charged state below $\sim 10$ TeV. This strongly motivates the construction of high-energy muon colliders, which are guaranteed to discover new physics: either by producing these new charged states directly, or by setting a strong lower bound on their mass, which would empirically prove that the universe is fine-tuned and violates the assumptions of MFV while somehow not generating large CLFVs. The former case is obviously the desired outcome, but the latter scenario would perhaps teach us even more about the universe by profoundly revising our understanding of naturalness, cosmological vacuum selection, and the SM flavour puzzle.

Dynamical analysis of interacting running vacuum models in DGP braneworld

The time dependent vacuum energy provides new mechanism for describing the entire cosmic history (from inflation to dark energy) of the universe. In the framework of DGP braneworld theory, we discuss the dynamical properties of varying vacuum cosmology by considering the interaction between the cosmological fluids. We engage various functional forms (linear and non-linear) of interaction term and apply dynamical system approach. In each case, we compute critical points as well as examine their existence and stability. These cosmological solutions describe the different cosmological eras. It is observed that in each case, system admits the stable critical points for small values of interaction parameter b (strength of interaction) which is a favorable condition from the observational point of view. We also develop the phase space portraits of the interaction models and find attractive behavior of the universe for the majority cases of interaction models.

How Neutrosophic Logic may Resolve Dispute on the Origin of the Universe through re-reading Gen. 1:1-2

In recent years, the Big Bang as described by the Lambda CDM-Standard Model Cosmology has become widely accepted by majority of physics and cosmology communities. But the philosophical problems remain, as Vaas pointed out: Did the universe have a beginning or does it exist forever, i.e. is it eternal at least in relation to the past? This fundamental question was a main topic in ancient philosophy of nature and the Middle Ages, and still has its revival in modern physical cosmology both in the controversy between the big bang and steady state models some decades ago and in the contemporary attempts to explain the big bang within a quantum cosmological (vacuum fluctuation) framework. In this paper we argue that Neutrosophic Logic offers a resolution to the long standing disputes between beginning and eternity of the Universe. In other words, in this respect we agree with Vaas, i.e. it can be shown: “how a conceptual and perhaps physical solution of the temporal aspect of Immanuel Kant’s „first antinomy of pure reason“ is possible, i.e. how our universe in some respect could have both a beginning and an eternal existence. Therefore, paradoxically, there might have been a time before time or a beginning of time in time.” By the help of computational simulation, we also show how a model of early Universe with rotation can fit this new picture. Further observations are recommended.

Interoception Modulates the Processing of Self and Other-Related Information

The time dependent vacuum energy provides new mechanism for describing the entire cosmic history (from inflation to dark energy) of the universe. In the framework of DGP braneworld theory, we discuss the dynamical properties of varying vacuum cosmology by considering the interaction between the cosmological fluids. We engage various functional forms (linear and non-linear) of interaction term and apply dynamical system approach. In each case, we compute critical points as well as examine their existence and stability. These cosmological solutions describe the different cosmological eras. It is observed that in each case, system admits the stable critical points for small values of interaction parameter b (strength of interaction) which is a favorable condition from the observational point of view. We also develop the phase space portraits of the interaction models and find attractive behavior of the universe for the majority cases of interaction models.

Structure of Space Fabric

This paper first proposes that a physical entity such as an electron and a cosmological entity such as a photon belong to two different levels of the Universe. When declaring that space is a vacuum, we are referring to the physical vacuum, and not the cosmological vacuum. The paper propounds that the space we observe is a fabric of cosmological substances. We cannot presume that something fills the emptiness of space. This paper posits that the fab-ric of cosmological substances creates this emptiness to facilitate physical activities such as electromagnetic waves and gravitational pull. Second, the space fabric is a spatial cosmo-logical phenomenon, whereas time is a physical phenomenon operated by a physical entity. The spacetime continuum is created by physical time acquiring the cosmological space fab-ric. The third part of this paper explains the structure and ingredients of the space fabric. The structure itself explains several cosmological phenomena, including electromagnetic waves, gravitation, light, magnetism, dark matter, and dark energy. The philosophical cor-rectness of the paper is validated through the unification of multidisciplinary aspects, and its scientific correctness is validated by its logical consistency with the results of well-known experiments.