Absence Of Matter Research Articles

Generation of Electric Current by Magnetic Field at the Boundary: Quantum Scale Anomaly Versus Semiclassical Meissner Current Outside of the Conformal Limit

AbstractThe scale (conformal) anomaly can generate an electric current near the boundary of a system in the presence of a static magnetic field. The magnitude of this magnetization current, produced at zero temperature and in the absence of matter, is proportional to a beta function associated with the renormalization of the electric charge. Using first‐principle lattice simulations, this paper investigates how the breaking of the scale symmetry affects this “scale magnetic effect” near a Dirichlet boundary in scalar quantum electrodynamics (Abelian Higgs model). This study demonstrates the interplay of the generated current with vortex excitations both in symmetric (normal) and broken (superconducting) phases and compares the results with the anomalous current produced in the conformal, scale‐invariant regime. Possible experimental signatures of the effect in Dirac semimetals are discussed.

Dark matter as a Weyl geometric effect

We investigate the possibility that the observed behavior of test particles outside galaxies, which is usually explained by assuming the existence of dark matter, is the result of the dynamical evolution of particles in a Weyl type geometry, and its associated conformally invariant Weyl geometric quadratic gravity. As a first step in our investigations we write down the simplest possible conformally invariant gravitational action, constructed in Weyl geometry, and containing the Weyl scalar, and the strength of the Weyl vector only. By introducing an auxiliary scalar field, the theoretical model can be reformulated in the Riemann geometry as scalar-vector-tensor theory, containing a scalar field, and the Weyl vector, respectively. The field equations of the theory are derived in the metric formalism, in the absence of matter. A specific static, spherically symmetric model, in which the Weyl vector has only a radial component, is considered. In this case, an exact analytic solution of the gravitational field equations can be obtained. The behavior of the galactic rotation curves is also considered in detail, and it is shown that an effective geometric mass term, with an associated density profile, can also be introduced. Three particular cases, corresponding to some specific functional forms of the Weyl vector, are also investigated. A comparison of the model with a selected sample of galactic rotation curves is also performed when an explicit breaking of conformal invariance is introduced, which allows the fix of the numerical values of the free parameters of the model. Our results show that Weyl geometric models can be considered as a viable theoretical alternative to the dark matter paradigm.

Black hole solutions in the quadratic Weyl conformal geometric theory of gravity

We consider numerical black hole solutions in the Weyl conformal geometry and its associated conformally invariant Weyl quadratic gravity. In this model, Einstein gravity (with a positive cosmological constant) is recovered in the spontaneously broken phase of Weyl gravity after the Weyl gauge field (omega _{mu }) becomes massive through a Stueckelberg mechanism and it decouples. As a first step in our investigations, we write down the conformally invariant gravitational action, containing a scalar degree of freedom and the Weyl vector. The field equations are derived from the variational principle in the absence of matter. By adopting a static spherically symmetric geometry, the vacuum field equations for the gravitational, scalar, and Weyl fields are obtained. After reformulating the field equations in a dimensionless form, and by introducing a suitable independent radial coordinate, we obtain their solutions numerically. We detect the formation of a black hole from the presence of a Killing horizon for the timelike Killing vector in the metric tensor components, indicating the existence of the singularity in the metric. Several models corresponding to different functional forms of the Weyl vector are considered. An exact black hole model corresponding to a Weyl vector having only a radial spacelike component is also obtained. The thermodynamic properties of the Weyl geometric type black holes (horizon temperature, specific heat, entropy, and evaporation time due to Hawking luminosity) are also analyzed in detail.

Cosmological constant and AdS spacetimes from Minkowski spheres

A theory of gravity without masses can be constructed starting from Minkowski [Formula: see text] spaces. The corresponding adapted (p, q) Minkowski potentials, gradients and Laplacians built on each signature lead to a field equation similar to the Newton-Laplace one. In this framework, the anti-de Sitter spacetime is a hypersurface described by a constant potential of Minkowski gravitational force in absence of matter. We show that the cosmological constant of the anti-de Sitter spacetimes is related to a geometric property of Minkowski spheres: the centro-affine conservation of volumes defined from the so-called Minkowski–Tzizteica affine spheres. It is possible to show the connection between the anti-de Sitter AdS(2, 3) space, the non-Euclidean geometry and the difference between Minkowski [Formula: see text] sphere and the pseudosphere seen as a surface of the 3-Euclidean space. According to a suitable parameterization, the relation between de Sitter and anti-de Sitter spacetimes in any dimension is fixed. As a consequence, the light can travel in any anti-de Sitter spacetime defining the geodesic structure. These considerations can be recast in terms of Einstein field equations with cosmological constant and extended to f(R) gravity.

Energy–momentum tensor and duality symmetry of linearized gravity in the Fierz formalism

A formulation of linearized gravity in flat background, based on the Fierz tensor as a counterpart of the electromagnetic field strength, is discussed in detail and used to study fundamental properties of the linearized gravitational field. In particular, the linearized Einstein equations are written as first order partial differential equations in terms of the Fierz tensor, in analogy with the first order Maxwell equations. An energy–momentum tensor with favourable properties and exhibiting remarkable similarity to the standard energy–momentum tensor of the electromagnetic field is found for the linearized gravitational field. is quadratic in the Fierz tensor (which is constructed from the first derivatives of the linearized metric), traceless, and satisfies the dominant energy condition in a gauge that contains the transverse traceless (TT) gauge. It is further shown that in suitable gauges, including the TT gauge, linearized gravity in the absence of matter has a duality symmetry that maps the Fierz tensor, which is antisymmetric in its first two indices, into its dual. Conserved currents associated with the gauge and duality symmetries of linearized gravity are also determined. These currents show good analogy with the corresponding currents in electrodynamics.

Propagation of axial and polar gravitational waves in Kantowski–Sachs universe

We apply the Regge-Wheeler formalism to study axial and polar gravitational waves in Kantowski-Sachs universe. The background field equations and the linearised perturbation equations for the modes are derived in presence of matter. To find analytical solutions, we analyze the propagation of waves in vacuum spacetime. The background field equations in absence of matter are solved by assuming the expansion scalar to be proportional to the shear scalar. Using the method of separation of variables, the axial perturbation parameter $ h_0(t, r) $ is obtained from its wave equation. The other perturbation $ h_1(t, r) $ is then determined from $ h_0(t, r) $. The anisotropy of the background spacetime is responsible for the damping of the axial waves. The polar perturbation equations are much more involved compared to their FLRW counterparts, as well as to the axial perturbations in Kantowski-Sachs background. In both the axial and polar cases, the radial and temporal solutions separate out as products. The temporal part of the polar perturbation solutions are plotted against time to obtain an order of magnitude estimate of the frequency of the propagating GWs and lies in the range 1000-2000 Hz. Using standard observational data for the GW strain we have placed constraints on the parameters in the polar perturbation solutions. The perturbation equations in presence of matter show that the axial waves can cause perturbations only in the azimuthal velocity of the fluid without deforming the matter field. But the polar waves must perturb the energy density, the pressure and also the non-azimuthal components of the fluid velocity.

Nonlinear Hamiltonian analysis of new quadratic torsion theories: Cases with curvature-free constraints

It was recently found that, when linearised in the absence of matter, 58 cases of the general gravitational theory with quadratic curvature and torsion are (i) free from ghosts and tachyons and (ii) power-counting renormalisable. We inspect the nonlinear Hamiltonian structure of the eight cases whose primary constraints do not depend on the curvature tensor. We confirm the particle spectra and unitarity of all these theories in the linear regime. We uncover qualitative dynamical changes in the nonlinear regimes of all eight cases, suggesting at least a broken gauge symmetry, and possibly the activation of negative kinetic energy spin-parity sectors and acausal behaviour. Two of the cases propagate a pair of massless modes at the linear level, and were interesting as candidate theories of gravity. However, we identify these modes with vector excitations, rather than the tensor polarisations of the graviton. Moreover, we show that these theories do not support a viable cosmological background.

Essential Quantum Einstein Gravity

The non-perturbative renormalisation of quantum gravity is investigated allowing for the metric to be reparameterised along the RG flow, such that only the essential couplings constants are renormalised. This allows us to identify a universality class of quantum gravity which is guaranteed to be unitary, since the physical degrees of freedom are those of general relativity without matter and with a vanishing cosmological constant. Considering all diffeomorphism invariant operators with up to four derivatives, only Newton’s constant is essential at the Gaussian infrared fixed point associated to the linearised Einstein–Hilbert action. The other inessential couplings can then be fixed to the values they take at the Gaussian fixed point along the RG flow within this universality class. In the ultraviolet, the corresponding beta function for Newton’s constant vanishes at the interacting Reuter fixed point. The properties of the Reuter fixed point are stable between the Einstein–Hilbert approximation and the approximation including all diffeomorphism invariant four derivative terms in the flow equation. Our results suggest that Newton’s constant is the only relevant essential coupling at the Reuter fixed point. Therefore, we conjecture that quantum Einstein gravity, the ultraviolet completion of Einstein’s theory of general relativity in the asymptotic safety scenario, has no free parameters in the absence of matter and in particular predicts a vanishing cosmological constant.

Gauging scale symmetry and inflation: Weyl versus Palatini gravity

We present a comparative study of inflation in two theories of quadratic gravity with gauged scale symmetry: (1) the original Weyl quadratic gravity and (2) the theory defined by a similar action but in the Palatini approach obtained by replacing the Weyl connection by its Palatini counterpart. These theories have different vectorial non-metricity induced by the gauge field (w_mu ) of this symmetry. Both theories have a novel spontaneous breaking of gauged scale symmetry, in the absence of matter, where the necessary scalar field is not added ad-hoc to this purpose but is of geometric origin and part of the quadratic action. The Einstein-Proca action (of w_mu ), Planck scale and metricity emerge in the broken phase after w_mu acquires mass (Stueckelberg mechanism), then decouples. In the presence of matter (phi _1), non-minimally coupled, the scalar potential is similar in both theories up to couplings and field rescaling. For small field values the potential is Higgs-like while for large fields inflation is possible. Due to their R^2 term, both theories have a small tensor-to-scalar ratio (rsim 10^{-3}), larger in Palatini case. For a fixed spectral index n_s, reducing the non-minimal coupling (xi _1) increases r which in Weyl theory is bounded from above by that of Starobinsky inflation. For a small enough xi _1le 10^{-3}, unlike the Palatini version, Weyl theory gives a dependence r(n_s) similar to that in Starobinsky inflation, while also protecting r against higher dimensional operators corrections.

Dynamics of a Homogeneous and Isotropic Space in Pure Cubic f(R) Gravity

The possible ways of dynamics of a homogeneous and isotropic space described by the Friedmann–Lemaitre–Robertson–Walker metric in the framework of cubic in the Ricci scalar f(R) gravity in the absence of matter are considered. This paper points towards an effective method for limiting the parameters of extended gravity models. A method for f(R)-gravity models, based on the metric dynamics of various model parameters in the simplest example is proposed. The influence of the parameters and initial conditions on further dynamics are discussed. The parameters can be limited by (i) slow growth of space, (ii) instability and (iii) divergence with the inflationary scenario.

The Chemoautotrophically Based Movile Cave Groundwater Ecosystem, a Hotspot of Subterranean Biodiversity

Movile Cave hosts one of the world’s most diverse subsurface invertebrate communities. In the absence of matter and energy input from the surface, this ecosystem relies entirely on in situ primary productivity by chemoautotrophic microorganisms. The energy source for these microorganisms is the oxidation of hydrogen sulfide provided continuously from the deep thermomineral aquifer, alongside methane, and ammonium. The microbial biofilms that cover the water surface, the cave walls, and the sediments, along with the free-swimming microorganisms, represent the food that protists, rotifers, nematodes, gastropods, and crustacean rely on. Voracious water-scorpions, leeches, and planarians form the peak of the aquatic food web in Movile Cave. The terrestrial community is even more diverse. It is composed of various species of worms, isopods, pseudoscorpions, spiders, centipedes, millipedes, springtails, diplurans, and beetles. An updated list of invertebrate species thriving in Movile Cave is provided herein. With 52 invertebrate species (21 aquatic and 31 terrestrial), of which 37 are endemic for this unusual, but fascinating environment, Movile Cave is the first known chemosynthesis-based groundwater ecosystem. Therefore, Movile Cave deserves stringent attention and protection.

Superradiance in Quantum Vacuum

A new process associated with the nonlinear optical properties of the electromagnetic quantum vacuum is described. It corresponds to the superradiant emission of photons, resulting from the interaction of an intense laser pulse with frequency ω0 with a counter-propagating high-harmonic signal with a spectrum of frequencies nω1, for n integer, in the absence of matter. Under certain conditions, photon emission from vacuum will be enhanced by the square of the number of intense spikes associated with the high-harmonic pulse. This occurs when the field created by the successive spikes is coherently emitted, as in typical superradiant processes involving atoms. Subradiant conditions, where the nonlinearity of quantum vacuum is entirely suppressed, can equally be defined.

Palatini quadratic gravity: spontaneous breaking of gauged scale symmetry and inflation

We study quadratic gravity R^2+R_{[mu nu ]}^2 in the Palatini formalism where the connection and the metric are independent. This action has a gauged scale symmetry (also known as Weyl gauge symmetry) of Weyl gauge field v_mu = (tilde{Gamma }_mu -Gamma _mu )/2, with tilde{Gamma }_mu (Gamma _mu ) the trace of the Palatini (Levi-Civita) connection, respectively. The underlying geometry is non-metric due to the R_{[mu nu ]}^2 term acting as a gauge kinetic term for v_mu . We show that this theory has an elegant spontaneous breaking of gauged scale symmetry and mass generation in the absence of matter, where the necessary scalar field (phi ) is not added ad-hoc to this purpose but is “extracted” from the R^2 term. The gauge field becomes massive by absorbing the derivative term partial _mu ln phi of the Stueckelberg field (“dilaton”). In the broken phase one finds the Einstein–Proca action of v_mu of mass proportional to the Planck scale Msim langle phi rangle , and a positive cosmological constant. Below this scale v_mu decouples, the connection becomes Levi-Civita and metricity and Einstein gravity are recovered. These results remain valid in the presence of non-minimally coupled scalar field (Higgs-like) with Palatini connection and the potential is computed. In this case the theory gives successful inflation and a specific prediction for the tensor-to-scalar ratio 0.007le rle 0.01 for current spectral index n_s (at 95% CL) and N=60 efolds. This value of r is mildly larger than in inflation in Weyl quadratic gravity of similar symmetry, due to different non-metricity. This establishes a connection between non-metricity and inflation predictions and enables us to test such theories by future CMB experiments.

Axial gravitational waves in Bianchi I universe

In this paper, we have studied the propagation of axial gravitational waves in Bianchi I universe using the Regge–Wheeler gauge. In this gauge, there are only two nonzero components of [Formula: see text] in the case of axial waves: [Formula: see text] and [Formula: see text]. The field equations in absence of matter have been derived both for the unperturbed as well as axially perturbed metric. These field equations are solved simultaneously by assuming the expansion scalar [Formula: see text] to be proportional to the shear scalar [Formula: see text] (so that [Formula: see text], where [Formula: see text], [Formula: see text] are the metric coefficients and [Formula: see text] is an arbitrary constant), and the wave equation for the perturbation parameter [Formula: see text] has been derived. We used the method of separation of variables to solve for this parameter, and have subsequently determined [Formula: see text]. We then discuss a few special cases to interpret the results. We find that the anisotropy of the background spacetime is responsible for the damping of the gravitational waves as they propagate through this spacetime. The perturbations depend on the values of the angular momentum [Formula: see text]. The field equations in the presence of matter reveal that the axially perturbed spacetime leads to perturbations only in the azimuthal velocity of the fluid leaving the matter field undisturbed.

A novel way of understanding the linear momentum of photon

Photon shows mass posing i.e. it manifests itself into various forms of rest mass; non-zero rest mass, wavelength-dependent real mass and imaginary rest mass within the dispersive medium. Photon reveals different forms of rest mass due to its illusive mass and the dual nature of photons is the cause of illusive mass. Here we have calculated the momentum of the photon on the surface of matter using illusive mass that implies a complex number. At certain condition (absence of matter) photon shows its linear momentum.

Twistor representation of Jackiw –Teitelboim gravity

Jackiw –Teitelboim (JT) gravity is a 1 + 1-dimensional toy model for quantum gravity in four spacetime dimensions. In the absence of matter, JT gravity is a topological field theory and there are no local observables. The introduction of a boundary changes the situation. What was an unphysical gauge direction before turns into a physical boundary degree of freedom (a gravitational edge mode). Starting from the BF formulation of JT gravity, we develop a twistor representation for the boundary charges of JT gravity. We introduce point sources in the bulk and study the coupled gravity plus matter system at the quantum level. Eigenstates of quasi-local energy are built from the tensor product of unitary irreducible representations of . Empty patches of AdS2 are characterised by the continuous series representations, point sources are related to the discrete series representations. Physical states are constructed by fusing the representations into an invariant singlet. The singlet lies in the kernel of the constraints, which are the analogue of the Wheeler – De Witt equations in the presence of distributional matter sources.

Stable, nonsingular bouncing universe with only a scalar mode

In this paper, we study a class of higher derivative, non-local gravity which admits homogeneous and isotropic non-singular, bouncing universes in the absence of matter. At the linearized level, the theory propagates only a scalar degree of freedom, and no vector or tensor modes. The scalar can be made free from perturbative ghost instabilities, and has oscillatory and bounded evolution across the bounce.

Conformal and kinetic couplings as two Jordan frames of the same theory

Certain scalar-tensor (ST) theories with non-minimal coupling of the scalar field to curvature may admit an Einstein frame representation, where gravity is described by the Einstein–Hilbert action plus the scalar sector. Between them, some theories exactly coincide in their respective Einstein frames. If transformations between Jordan and Einstein frames are invertible, these theories can be associated with two Jordan frames of the unique theory. Such successive dualities can connect theories with non-derivative coupling, like Rphi ^2, with derivatively coupled theories, like Horndeski and DHOST. In absence of matter, these are equivalent, though looking very different. We show the existence of a successive duality between the Rphi ^2 theory and a recently found Palatini kinetically coupled theory, which both look in their Einstein frames as Einstein theory minimally coupled to scalar. Transforming singular exact solutions of the latter to Jordan frames, we compare desingularization properties of the above two theories which both violate the null energy condition. It is found that kinetically coupled theory has stronger desingularization features, exhibiting possibility of Genesis-type behavior of the homogeneous and isotropic cosmological solutions.

Corporate Responsibilities on the Action of Human Trafficking Criminals in Indonesia

<p>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.</p>

The Role of Natural Philosophy in the Beginning of Metaphysics

The Role of Natural Philosophy in the Beginning of Metaphysics Glen Coughlin THIS ESSAY concerns an issue controverted in Thomistic circles, namely, whether one must prove the existence of immaterial beings in natural philosophy before one can begin the scientific study of metaphysics. By "metaphysics," I mean a science1 of being just as being (ens commune or ens inquantum ens)2 and not as restricted to some determinate sort [End Page 395] of being, such as quantified or mobile being, the subjects respectively of mathematics and natural philosophy.3 Being as such includes immaterial beings, such as separate intelligences and intellectual souls, as well as material beings, such as plants and animals.4 All Thomists hold that such immaterial things exist. But do we have to know that they exist before we begin the science of being as such? And, if so, how do we go about learning that they exist?5 My claim is the traditional one,6 that we do have to know of the existence of immaterial beings to begin the scientific study of metaphysics, and that we learn of their existence through natural philosophy.7 [End Page 396] I. Generalization We might think we can bypass the problem of proving the existence of the immaterial and go directly to metaphysics. If metaphysics is about being in common or being as being, one might think that there can be a science of metaphysics simply because we have the universal name "being," and especially because St. Thomas Aquinas and Aristotle say that in pursuing a science we should start with what is more general.8 It seems that metaphysics is not only possible right away, but ought to be the very first philosophy we study, perhaps after logic. "Being" certainly does seem to name something more universal than "mobile being," the subject of natural philosophy, for the adjective "mobile" qualifies and limits the noun "being." But there are problems with this simple position. A new science demands a new mode of definition, and mere generality does not suffice. The discussion of figures, though more general than the discussion of triangles, does not belong to some more universal science of mathematics. The division of the speculative sciences, according to St. Thomas, is based not upon generality, but upon the degrees of materiality found in the definitions of the subject-genera of the sciences.9 The reason for this is that every habit (and science is a habit of knowing something by way of a syllogism)10 is defined in terms of its [End Page 397] object.11 But the objects of science are things insofar as they are intelligible. Because intelligibility is due to removal from matter,12 the object of every speculative science is something removed from matter, and the kinds of intelligibility (and so the species of science) are determined by the kinds of removal.13 The ways in which the sciences differ per se, then, is by the presence or absence of matter in their subject-genera. Some things have sensible matter in their definitions, like natural things (e.g., horses and dogs, rocks and fires, cannot be or be understood without reference to sensible qualities like color, weight, hardness, etc.); others do not, but only have "intelligible matter." Squares and rectangles, being accidents, cannot exist apart from a substance in which they inhere. That substance is then a sort of matter, but it is perceivable only by the intellect, and so is called "intelligible matter."14 Things defined with sensible matter are studied by natural philosophy, those without, but with intelligible matter, by mathematics. Those things without any matter in their definition at all (e.g., being, one, and separate substances), are studied by metaphysics.15 Here things become a little more complicated because St. Thomas gives more than one description of the science of metaphysics. Sometimes he says it concerns being as being, sometimes the first causes, sometimes the immaterial. How can it be about all three of these? It is not about all of them as [End Page 398] subjects, though it is in a sense about all of them. It is about being as being in the sense of a...