Absence Of Matter Research Articles

Cosmology of minimal varying Lambda theories

Inserting a varying Lambda in Einstein's field equations can be made consistent with the Bianchi identities by allowing for torsion, without the need to add scalar field degrees of freedom. In the minimal such theory, Lambda is totally free and undetermined by the field equations in the absence of matter. Inclusion of matter ties Lambda algebraically to it, at least when homogeneity and isotropy are assumed, i.e. when there is no Weyl curvature. We show that Lambda is proportional to the matter density, with a proportionality constant depending on the equation of state. Unfortunately, the proportionality constant becomes infinite for pure radiation, ruling out the minimal theory prima facie despite of its novel internal consistency. It is possible to generalize the theory still without the addition of kinetic terms, leading to a new algebraically-enforced proportionality between Lambda and the matter density. Lambda and radiation may now coexist in a form consistent with Big Bang Nucleosynthesis, though this places strict constraints on the single free parameter of the theory, $\theta$. In the matter epoch Lambda behaves just like a dark matter component. Its density is proportional to the baryonic and/or dark matter, and its presence and gravitational effects would need to be included in accounting for the necessary dark matter in our Universe. This is a companion paper to Ref. [1] where the underlying gravitational theory is developed in detail.

Recovering the cosmological constant from affine geometry

A gravity theory without masses can be constructed in Minkowski spaces using a geometric Minkowski potential. The related affine spacelike spheres can be seen as the regions of the Minkowski spacelike vectors characterized by a constant Minkowski gravitational potential. These spheres point out, for each dimension [Formula: see text], spacetime models, the de Sitter ones, which satisfy Einstein’s field equations in absence of matter. In other words, it is possible to generate geometrically the cosmological constant. Even if a lot of possible parameterizations have been proposed, each one highlighting some geometric and physical properties of the de Sitter space, we present here a new natural parameterization which reveals the intrinsic geometric nature of cosmological constant relating it with the invariant affine radius coming from the so-called Minkowski–Tzitzeica surfaces theory.

Corporate Responsibilities on The Action of Human Trafficking Criminals in Indonesia

Problems related to human rights in Indonesia are criminal acts of human trafficking committed by corporations. Trafficking in persons is a modern form of human slavery and is also one of the worst forms of treatment of violations of human dignity. However, the development has difficulties with law enforcement related to corporations that commit criminal acts of trafficking. The research method used is a normative juridical research method using secondary data to be analyzed qualitatively. The results of this study show that corporations as subjects of criminal law can be equated with humans, because there are rights and obligations given by law and therefore corporate skills are also equated with human skills. Regulations regarding corporate responsibility are regulated in Law Number 21 of 2007 concerning Eradication of Criminal Act of Human Trafficking, corporations can be held liable if they commit criminal acts of trafficking by fulfilling the requirements of criminal liability in general such as the ability to be responsible, mistakes and intentions, absence of matters that are used as reasons for criminal offenses.

Higher derivative corrections to Kerr black hole thermodynamics

In an effective field theory approach to gravity, the Einstein-Hilbert action is supplemented by higher derivative terms. In the absence of matter, four derivative terms can be eliminated by a field redefinition. We use the Euclidean action to calculate analytically the corrections to thermodynamic quantities of the Kerr solution arising from terms with six or eight derivatives. The eight derivative terms make a non-negative correction to the entropy (at fixed mass and angular momentum) if their coefficients have appropriate signs. The correction from the six derivative terms does not have a definite sign.

The physical nature of subjective experience and its interaction with the brain

Penrose and Hameroff assert that brain computations, including quantum computations, involving hydrophobic areas of microtubules whose electron clouds go into orchestrated superpositions and reductions that lead to proto-conscious elements, or “bings” that become orchestrated into conscious experiences. Their assertion, however, like the findings of the neural correlates of consciousness, does not explain subjectivity, but rather describes necessary conditions for it. Many scientists, including Panksepp, Demasio, and Tononi, have each made great contributions to the field, but none explains how material biological processes acquire subjectivity.Yet, the fact is that subjectivity exists and is and of great importance to evolution. Penrose argues that understanding, which involves subjectivity, must be brought into physics, perhaps an undiscovered aspect. Subjectivity is always of or about certain living brain information even though most brain functions do not have subjectivity.Many quantum fields are known to exist and follow Dyson's definition: “a kind of tension or stress which can exist in empty space in the absence of matter. It reveals itself by producing forces, which act on any material objects that happen to lie in the space the field occupies.”My hypothesis is that there may be undiscovered quantum fields, which unlike known fields, induce subjectivity when they interact with certain brain information. They emit quantum particles that exert force and cause changes to material objects (brain patterns conveying information) with which they interact. Information that transports meaning to living material exerts force through the understanding it conveys. There is a continuous interplay between experience and brain information. Experiences profoundly inform the brain and alter brain structure, function, and behavior, and local and integrated brain functions process information and initiate multiple associated experiences.Most experience is non-conscious, as discussed by Wright and others, like the soundtrack of a movie to which our brains respond continuously and emotionally even though, we are only intermittently consciously aware of it. I will explore how non-conscious experience may relate to the self, and how it might become conscious. I will offer present support and directions for testing this plausible hypothesis, as well as potential clinical applications in psychology.

The cosmological constant in supergravity

We propose a supersymmetrisation of the cosmological constant in ordinary N=1 supergravity that breaks supersymmetry spontaneously by a constant Fayet-Iliopoulos (FI) term associated to a U(1) symmetry. This term is a variation of a new gauge invariant FI term proposed recently, which is invariant under Kähler transformations and can be written even for a gauged R-symmetry on top of the standard FI contribution. The two terms are the same in the absence of matter but differ in its presence. The proposed term is reduced to a constant FI-term up to fermion interactions that disappear in the unitary gauge in the absence of any F-term supersymmetry breaking. The constant FI term leads to a positive cosmological constant, uplifting the vacuum energy from the usual anti-de Sitter supergravity to any higher value.

Autonomous dynamical system approach for inflationary Gauss–Bonnet modified gravity

In this paper, we shall analyze the [Formula: see text] gravity phase space, in the case that the corresponding dynamical system is autonomous. In order to make the dynamical system autonomous, we shall appropriately choose the independent variables, and we shall analyze the evolution of the variables numerically, emphasizing on the inflationary attractors. As we demonstrate, the dynamical system has only one de Sitter fixed point, which is unstable, with the instability being traced in one of the independent variables. This result holds true both in the presence and in the absence of matter and radiation perfect fluids. We argue that this instability could loosely be viewed as an indication of graceful exit in the [Formula: see text] theory of gravity.

Area deficits and the Bel–Robinson tensor

The first law of causal diamonds relates the area deficit of a small ball relative to flat space to the matter energy density it contains. At second order in the Riemann normal coordinate expansion, this energy density should receive contributions from the gravitational field itself. In this work, we study the second-order area deficit of the ball in the absence of matter and analyze its relation to possible notions of gravitational energy. In the small ball limit, a reasonable expectation for any proposed gravitational energy functional is that it evaluate to the Bel–Robinson energy density W in vacuum spacetimes. A direct calculation of the area deficit reveals a result that is not simply proportional to W. We discuss how the deviation from W is related to ambiguities in defining the shape of the ball in curved space, and provide several proposals for fixing these shape ambiguities.

On gravitational energy in conformal teleparallel gravity

The paper deals with the definition of gravitational energy in conformal teleparallel gravity. The total energy is defined by means of the field equations which allow a local conservation law. Then such an expression is analyzed for a homogeneous and isotropic Universe. This model is implemented by the Friedmann–Robertson–Walker (FRW) line element. The energy of the Universe in the absence of matter is identified with the dark energy, however it can be expanded for curved models defining such an energy as the difference between the total energy and the energy of the perfect fluid which is the matter field in the FRW model.

Mimetic Dark Matter in Pseudo-Complex General Relativity

We investigate the dark matter problem in the context of Pseudo-complex General Relativity. A form of gravitational dark matter has recently been studied, the mimetic dark matter, which is a scalar tensor extension for gravity where the conformal degree of freedom is isolated in a covariant way. For such, we perform a combination of both approaches to reveal non trivial results even in the absence of matter. Solutions for different scenarios and possible interpretations are presented.

Reconstruction of f ( T ) $f(T)$ -gravity in the absence of matter

We derive an exact $f(T)$ gravity in the absence of ordinary matter in Friedmann-Robertson-Walker (FRW) universe, where $T$ is the teleparallel torsion scalar. We show that vanishing of the energy-momentum tensor $\mathcal{T}^{\mu \nu}$ of matter does not imply vanishing of the teleparallel torsion scalar, in contrast to general relativity, where the Ricci scalar vanishes. The theory provides an exponential (inflationary) scale factor independent of the choice of the sectional curvature. In addition, the obtained $f(T)$ acts just like cosmological constant in the flat space model. Nevertheless, it is dynamical in non-flat models. In particular, the open universe provides a decaying pattern of the $f(T)$ contributing directly to solve the fine-tuning problem of the cosmological constant. The equation of state (EoS) of the torsion vacuum fluid has been studied in positive and negative Hubble regimes. We study the case when the torsion is made of a scalar field (tlaplon) which acts as torsion potential. This treatment enables to induce a tlaplon field sensitive to the symmetry of the spacetime in addition to the reconstruction of its effective potential from the $f(T)$ theory. The theory provides six different versions of inflationary models. The real solutions are mainly quadratic, the complex solutions, remarkably, provide Higgs-like potential.

Cosmological perturbations in mimetic Horndeski gravity

We study linear scalar perturbations around a flat FLRW background in mimetic Horndeski gravity. In the absence of matter, we show that the Newtonian potential satisfies a second-order differential equation with no spatial derivatives. This implies that the sound speed for scalar perturbations is exactly zero on this background. We also show that in mimetic G3 theories the sound speed is equally zero. We obtain the equation of motion for the comoving curvature perturbation (first order differential equation) and solve it to find that the comoving curvature perturbation is constant on all scales in mimetic Horndeski gravity. We find solutions for the Newtonian potential evolution equation in two simple models. Finally we show that the sound speed is zero on all backgrounds and therefore the system does not have any wave-like scalar degrees of freedom.

Gravitational behavior of an effective topological field theory in a gravitational instanton background

Effective topological field theories describe the properties of Dirac fermions in the low-energy regime. In this work, we introduce a new emergent gravity model by considering Dirac fermions invariant under local de Sitter transformations in four-dimensional open manifolds. In the context of Cartan geometry, fermions couple to spacetime through a Spin(5) Cartan connection that can be decomposed in spin connection and tetrads. In presence of a gravitational instanton background, we show that the corresponding effective topological field theory becomes a dynamical gravitational theory with a positive cosmological constant and Barbero–Immirzi parameter. At the classical level and in the absence of matter, this theory is compatible with general relativity (GR).

A Note from the Editor

A Note from the Editor Lisa S. Brenner, Coeditor The phrase devised theatre seems to crop up everywhere: in articles, on websites, in reviews, and especially in the sessions, hallways, and hotel bars at the conferences of the Association for Theatre in Higher Education (ATHE). Hearing the words devised theatre transports me back to my post-college days, working as a director of a feminist theatre company in Philadelphia called The Women’s Ensemble. At that time, my colleagues and I positioned ourselves antithetically to what we considered to be the patriarchal structure of traditional theatre. We deliberately created our work as a collective, often stringing together pieces in an episodic form that allowed for various, even conflicting authorial voices. It was the early ’90s. Twenty years later, attending ATHE conferences as a college professor, I began to reframe this previous work under the rubric of devised theatre. But I had questions about what it means to create devised theatre: Is devising a performance an aesthetic choice or a sociopolitical stance? What techniques are best? How much should a director lead the process, and when and in what ways should a director step back? What is the role of the playwright in devising? When I joined the editorial team at Theatre Topics I was therefore compelled to take a deeper dive into exploring this approach to theatre-making. Clearly, I was not alone in this inquiry. A 2015 issue of The Dramatist featured a roundtable discussion with the indicative title, “What Is Devised Theatre?” Most scholars and practitioners would likely agree with Alison Oddey’s notion that devised theatre is “a response and reaction to the playwright–director relationship, to text-based theatre, and to naturalism, and challenges the prevailing ideology of one person’s text under another’s direction” (4). However, if devised theatre is mostly recognized as an alternative to the predominant form of theatre-making, as Moisés Kaufman articulates, this categorization only describes “what something is not” (qtd. in Groff 18). Comparing devised theatre to a black hole (which is an absence of matter), Kaufman further explicates that “we know how theater is most often made, and devised is everything that is not that” (23). At the same time, even this (negative) description does not always remain within clear boundaries. In an interview with American Theatre, for example, Young Jean Lee describes her playwriting process: I’ll write a scene and bring it into rehearsal and see if it works. If it’s a total failure, I just throw it out. If it has potential, then I rewrite it with the actors on their feet. I’ll have them making changes in their scripts, then I’ll take it home, rewrite it, and bring it in the next day. And eventually I can see a shape. . . . There is no script [on] day one of rehearsal. There’s just a scene that I bring in. (qtd. in Jones 75) Yet, how often is Lee referred to as a deviser? In the decade plus since Theatre Topics last devoted a special issue to devising (15.1, 2005), its query “Why devise? Why now?” has continued to engage theatre artists and educators. In fact, the popularity and impact of this type of theatre has significantly grown over time. Reflecting on the tremendous critical and commercial success of War House, the New York Times recently noted a shifting of the tide: “Historically, British theater has centered on the playwright, but for the ‘most successful show of the last decade’ to be a devised project is a ‘great provocation,’” with devised shows like London Road and Curious Incident following suit (Trueman C6). At the same time, devised [End Page ix] theatre seems to be on the rise on college and university campuses and often serves as the basis for theatre for social justice. While not wishing to provide a definitive or prescriptive use of the term devised, this special issue attempts to bring the concept into sharper focus. The essays included explore the role of devising as an aesthetic practice, a pedagogic practice, and an applied theatre practice. In addition to the questions of “Why devise? Why now?” the contributors ask...

String Theory backgrounds with Torsion in the presence of Fermions and implications for Leptogenesis

Fermions couple in a universal way to the the Kalb-Ramond field which occurs in the gravitational multiplet of string theory. The Kalb-Ramond field is a source of torsion and can provide a background for fermion dynamics. Solutions for this background in terms of the string effective action are discussed and are fixed ’’points” of conformal invariance conditions. Nonperturbative fixed points for the torsion in the absence of matter are shown to be compatible with perturbative fixed points in the presence of matter. Fermion coupling to such backgrounds can lead to both CP and CPT violation. Hence torsion can give a new mechanism for leptogenesis. The presence of anomalies in the Bianchi identity for the torsion, in the presence of matter, is crucial in giving a background solution for the torsion and dilaton with an acceptable cosmology.

Little Rip, ΛCDM and singular dark energy cosmology from Born–Infeld-[formula omitted] gravity

We study late-time cosmic accelerating dynamics from Born–Infeld-f(R) gravity in a simplified conformal approach. We find that a variety of cosmic effects such as Little Rip, ΛCDM universe and dark energy cosmology with finite-time future singularities may occur. Unlike the convenient Born–Infeld gravity where in the absence of matter only de Sitter expansion may emerge, apparently any FRW cosmology maybe reconstructed from this conformal version of the Born–Infeld-f(R) theory. Despite the fact that the explicit form of f(R) is fixed by the conformal ansatz, the relation between the two metrics in this approach may be changed so as to bring out any desired FRW cosmology.

Dark energy from holographic theories with hyperscaling violation

We show that analytical continuation maps scalar solitonic solutions of Einstein-scalar gravity, interpolating between an hyperscaling violating and an Anti de Sitter (AdS) region, in flat FLRW cosmological solutions sourced by a scalar field. We generate in this way exact FLRW solutions that can be used to model cosmological evolution driven by dark energy (a quintessence field) and usual matter. In absence of matter, the flow from the hyperscaling violating regime to the conformal AdS fixed point in holographic models corresponds to cosmological evolution from power-law expansion at early cosmic times to a de Sitter (dS) stable fixed point at late times. In presence of matter, we have a scaling regime at early times, followed by an intermediate regime in which dark energy tracks matter. At late times the solution exits the scaling regime with a sharp transition to a dS spacetime. The phase transition between hyperscaling violation and conformal fixed point observed in holographic gravity has a cosmological counterpart in the transition between a scaling era and a dS era dominated by the energy of the vacuum.

Pre-Big Bang, space-time structure, asymptotic Universe

Planck and other recent data in Cosmology and Particle Physics can open the way to controversial analyses concerning the early Universe and its possible ultimate origin. Alternatives to standard cosmology include pre-Big Bang approaches, new space-time geometries and new ultimate constituents of matter. Basic issues related to a possible new cosmology along these lines clearly deserve further exploration. The Planck collaboration reports an age of the Universe t close to 13.8 Gyr and a present ratio H between relative speeds and distances at cosmic scale around 67.3 km/s/Mpc. The product of these two measured quantities is then slightly below 1 (about 0.95), while it can be exactly 1 in the absence of matter and cosmological constant in patterns based on the spinorial space-time we have considered in previous papers. In this description of space-time we first suggested in 1996-97, the cosmic time t is given by the modulus of a SU(2) spinor and the Lundmark-Lemaitre-Hubble (LLH) expansion law turns out to be of purely geometric origin previous to any introduction of standard matter and relativity. Such a fundamental geometry, inspired by the role of half-integer spin in Particle Physics, may reflect an equilibrium between the dynamics of the ultimate constituents of matter and the deep structure of space and time. Taking into account the observed cosmic acceleration, the present situation suggests that the value of 1 can be a natural asymptotic limit for the product H t in the long-term evolution of our Universe up to possible small corrections. In the presence of a spinorial space-time geometry, no ad hoc combination of dark matter and dark energy would in any case be needed to get an acceptable value of H and an evolution of the Universe compatible with observation. The use of a spinorial space-time naturally leads to unconventional properties for the space curvature term in Friedmann-like equations. It therefore suggests a major modification of the standard cosmology based on general relativity. In the new cosmology thus introduced, the contribution of the space curvature to the value of H 2 is positive definite independently of the apparent sign of this curvature, and has a much larger value than the standard curvature term. Then, a cosmological constant is no longer required. The spinorial space-time also generates automatically for each comoving observer a privileged space direction that, together with parity violation, may explain the anisotropies observed in WMAP and Planck data. Contrary to frequent statements, such a signature would not be a strange phenomenon. The effect emerges directly from the use of two complex space-time coordinates instead of the conventional four real ones, and the privileged direction would correspond to the phase of the cosmic spinor. We remind here our previous work on the subject and further discuss some cosmological implications of the spinorial space-time.

Mimetic dark matter

Abstract We modify Einstein’s theory of gravity, isolating the conformal degree of freedom in a covariant way. This is done by introducing a physical metric defined in terms of an auxiliary metric and a scalar field appearing through its first derivatives. The resulting equations of motion split into a traceless equation obtained through variation with respect to the auxiliary metric and an additional differential equation for the trace part. As a result the conformal degree of freedom becomes dynamical even in the absence of matter. We show that this extra degree of freedom can mimic cold dark matter.

Diffusion and Convective Instability in Ternary Gas Mixture

The main objective of this article is to investigate the evolution of the mass transfer regimes in three-component gas mixture subject to the pressure and the diameter of diffusion channel. Two series of experiments on gaseous diffusion instabilities are reported. In one series the stability limits are investigated as a function of pressure and diameter for the system 0.4722 He + 0.5278 Ar - N2. In the other series the convection structures are made visible with the help of shadow method. The experimentalresults reveal that an increase in the pressure and the diameter of diffusion channel leads to a change of the type of mixing in ternary gas mixture.Numerical analysis of the mixing process is studied in a vertical cylindrical channel of a finite size and at the isothermal conditions. The governing equations are solved at the boundary conditions assuming the absence of matter through the walls of diffusion channel. Through the Rayleigh partial numbers, the influences of the pressure and the diameter of diffusion channel on the behaviour of diffusion and convective flows are examined. The present results are in good agreement with the experimental data.