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We show that the first-order expansion of parameter κ of Eddington - inspired Born Infeld (EiBI) theory of gravity yields a Tolman-Oppenheimer-Volkoff (TOV) equation for anisotropic stars which is equivalent to the one of general relativity (GR) theory. It is also evidence that, for the non-relativistic limit, the radial pressure gradient of the corresponding first-order GR-like expansion of EiBI theory is exactly the same as the one of EiBI theory. We also investigate the mass-radius relation of neutron stars predicted by first-order GR-like expansion of EiBI theory. The results are compared to the exact one to see how good the corresponding expansion. [ABSTRACT FROM AUTHOR]

In this paper, we present the main ideas of Euclidean Closed Linear Transformations of Complex Spacetime endowed with the Corresponding Metrics (ECLTCSCMs), which unify Theories of Physics (TPs), such as Newtonian physics (NPs) etc, keeping Einstein Relativity Theory's (ERT's) formalism. Thus, we may obtain physical results, which contain a Fundamental Parameter (ωI), depending on the spacetime metrics of the Relativistic Inertial Observers (RIOs) of each specific TPs. This unification give us the capability of modifying objects of one TPs (like NPs) in order to be used in another TPs (like ERT). For example, we begin from the metric-gravitation of Modified Newtonian Dynamics (MOND) and we obtain a new metric-gravitation which is in accordance with ERT. This application to Megacosmos, explains the rotation curves in galaxies and solar systems, eliminating Dark Matter. Besides, the specific value ωI=±i gives Vossos transformation (VT) endowed with Lorentz metric of complex spacetime and invariant spacetime interval (or equivalently invariant speed of light in vacuum), producing the theory of Euclidean Complex Relativistic Mechanics (ECRMs) which is associated with ERT. Applying the aforementioned theory to Microcosmos, we calculate the position of the fine structure peaks of the atomic hydrogen spectrum. The result is better not only than this extracted using P. Dirac theory, but also than that of L. H. Thomas method. [ABSTRACT FROM AUTHOR]

Inspired by recent works, we investigate how the thermodynamics parameters (entropy, temperature, number density, energy density, etc) of Bose-Einstein Condensate star scale with the structure of the star. Below the critical temperature in which the condensation starts to occur, we study how the entropy behaves with varying temperature till it reaches its own stability against gravitational collapse and singularity. Compared to photon gases (pressure is described by radiation) where the chemical potential, μ is zero, entropy of photon gases obeys the Stefan-Boltzmann Law for a small values of T while forming a spiral structure for a large values of T due to general relativity. The entropy density of Bose-Einstein Condensate is obtained following the similar sequence but limited under critical temperature condition. We adopt the scalar field equation of state in Thomas-Fermi limit to study the characteristics of relativistic Bose-Einstein condensate under varying temperature and entropy. Finally, we obtain the entropy density proportional to (σT³-3T) which obeys the Stefan-Boltzmann Law in ultra-relativistic condition. [ABSTRACT FROM AUTHOR]

Since the appearance of Einstein's general relativity, gravitation has been associated to the space-time curvature. This theory introduced a geometrodynamic language which became a convenient tool to predict matter behaviour. However, the properties of space-time itself cannot be measurable by experiments. Taking Poincare idea that the geometry of space-time is merely a convention, we show that the general theory of relativity can be completely reformulated in a more general setting, a generalization of Riemannian geometry, namely, the Weyl integrable geometry. The choice of this new mathematical language implies, among other things, that the path of particles and light rays should now correspond to Weylian geodesics. Such modification in the dynamic of bodies brings a new perception of physical phenomena that we will explore. [ABSTRACT FROM AUTHOR]

In this lecture, we will present some nucleonic equations of state of neutron-star matter calculated within the nuclear energy-density functional theory using generalized Skyrme functionals developed by the Brussels-Montreal collaboration. These equations of state provide a consistent description of all regions of a neutron star. The global structure of neutron stars predicted by these equations of state will be discussed in connection with recent astrophysical observations. [ABSTRACT FROM AUTHOR]

General Relativity is based on the Einstein Equivalence Principle consisting of the Universality of Free Fall, the Universality of the Gravitational Redshift and Local Lorentz Invariance. Stating these principles already employs some further underlying assumptions. These assumptions are related to the famous Newton’s axioms. Accordingly, the existence of inertial systems, the form of the equation of motion and of the law of reciprocal action will be discussed in this article. Conditions are given which allow to test these underlying assumptions. [ABSTRACT FROM AUTHOR]

Relativistic quantum information (RQI) is an emerging field of research dedicated to investigating quantum information protocols in a relativistic setting. Such models may give us clues about what sort of features a proper theory of quantum gravity ought to have. In this paper, we consider what happens to a quantum circuit operating in a curved spacetime background. We model the circuit using quantum optics in a Schwarzchild metric, with qubits constructed from single photons. The result is compared to an alternative model using ‘event operators’ in place of regular quantum optics. In this new model, field operators acting at different events in the photon’s history are made to commute with each other; a requirement that has elsewhere been shown to remove paradoxes from situations where closed time-like curves are involved. Our comparison of the models reveals that the event operator model is inherently non-linear, although it gives the same predictions as normal quantum optics in most cases. [ABSTRACT FROM AUTHOR]

We present some of the recent results and open questions on the causality problem in General Relativity. The concept of singularity is intimately connected with future trapped surface and inner event horizon formation. We offer a brief overview of the Hawking-Penrose singularity theorems [1] and discuss a few open problems concerning the future Cauchy development (domain of dependence) [11], break-down criteria and energy conditions for the horizon stability. A key question is whether causality violating regions, generating a Cauchy horizon are allowed. We raise several questions concerning the invisibility and stability of closed trapped surfaces from future null infinity and derive the imprisonment conditions. We provide an up-to-date perspective of the causal boundaries and spacelike conformal boundary extensions for time oriented Lorentzian manifolds and more exotic settings. [ABSTRACT FROM AUTHOR]

The existence of gravitational waves was predicted by Albert Einstein. Black hole and neutron star binary systems will product strong gravitational waves through their inspiral and eventual merger. The analysis of the gravitational wave data is computationally intensive, requiring matched filtering of terabytes of data with a bank of at least 3000 numerical templates that represent predicted waveforms. We need to complete the analysis in real-time (within the duration of the signal) in order to enable follow-up observations with some conventional optical or radio telescopes. We report a novel application of a graphics processing units (GPUs) for the purpose of accelerating the search pipelines for gravitational waves from coalescing binary systems of compact objects. A speed-up of 16 fold in total has been achieved with an NVIDIA GeForce 8800 Ultra GPU card compared with a standard central processing unit (CPU). We show that further improvements are possible and discuss the reduction in CPU number required for the detection of inspiral sources afforded by the use of GPUs. [ABSTRACT FROM AUTHOR]

Recent advances in ground-based interferometric gravitational wave detectors have produced a high level of confidence in detection of transient gravitational wave signals generated by coalescing neutron star or black hole binaries. The combination of gravitational wave data and associated electromagnetic radiation observed by telescopes will allow precision testing of general relativity, including measurement of the speed of gravitational waves. We present a new method of detection based on Infinite Impulse response (IIR) filtering with the goal of computing signal to noise ratios in near real time (low-latency). We then apply a set of IIR filters to the incoming detector data and coherent sum the outputs to produce near optimal signal to noise ratio. Our results show a computation time speed-up of >50 times compared with standard time-domain matched filter methods. [ABSTRACT FROM AUTHOR]

Deterministic and nondeterministic approaches are widely used in physics in relativistic and quantum theories. The questions of general consistency of these theories and the principal possibility of their unification are considered. There is proposed the way to unification of deterministic and nondeterministic approaches in non-contradictive system. Some consequences of this supposition are considered and discussed. [ABSTRACT FROM AUTHOR]

We discuss why there are no negative gravitational sources in General Relativity and show that it is possible to extend the classical theory such that repulsive gravitational interaction occurs. This is the summary of a talk given at the 17th International Conference on Supersymmetry and the Unification of Fundamental Interactions in Boston, June 2009. [ABSTRACT FROM AUTHOR]

Workable engineering models for long range forces and spacecraft dynamics are based on Newton laws and Maxwell equations. These models are currently in use but look incomplete, as for instance they fail to account for observed anomalies in interplanetary spacecraft trajectories. In addition Newton laws fail to predict gravitational waves. The most advanced relativistic models of gravity have been suggested for building engineering models, but most of them resulted in complex formulations of difficult interpretation. The questions are: can we develop a simple unified model for long range forces capable of describing the observed reality which could be easily integrated in high-speed spacecraft design and trajectory calculation? Moreover, can we build models for wave propagation using a single formalism, thus integrating electromagnetic waves and gravitational waves? Can we adopt these models for studying High Frequency Gravitational Waves (HFGW) in order to apply them to space travel, communications, imaging, cosmology, etc? To do that, it is clearly necessary to take into account all know observational results. On the other hand we must be free to adopt and elaborate on what has been recognized to be the most successful and better understood formulation for a long range force, that is Maxwell equations, and work towards a unified approach. [ABSTRACT FROM AUTHOR]

We investigate the gravitational lensing effect in presence of plasma. We observe that in a homogeneous plasma the gravitational deflection angle differs from that in vacuum, and it depends on the frequency of the photon. We discuss observational consequences of this dependence for the point-mass lensing and estimate possibility of the observation of this effect by the planned project Radioastron. [ABSTRACT FROM AUTHOR]

The problems of formation and evolution of pulsars in close binaries is considered. The first discovered binary pulsar called Hulse-Taylor pulsar, on the name of discoverers. Observations indicate to existence of single recycled pulsars, and disruption of pulsar pairs, by the mechanism of enhanced evaporation, is considered. The best laboratory of a study of General Relativity is a system of two neutron stars, where one, or two of them are radiopulsars. Hulse-Taylor pulsar, and recently discovered system containing two radiopulsars (a Double pulsar system) are the best objects for these studies. In addition to checking the validity of general relativity, these systems are used for putting limits to the variability of the gravitational constant. Future measurements of nonlinear GR effects may be used for estimations of the properties of a superdense matter inside neutron stars. [ABSTRACT FROM AUTHOR]

The fully constrained formulation (FCF) proposed by Bonazzola, Gourgoulhon, Grand-clément, and Novak is one of the constrained formulations of Einstein’s equations. It contains as an approximation the conformal flatness condition (CFC). The elliptic part of the FCF basically shares the same differential operators as the elliptic equations in the CFC scheme. We present here a reformulation of the elliptic sector of CFC that has the fundamental property of overcoming local uniqueness problems, and an extension of these ideas to FCF. [ABSTRACT FROM AUTHOR]

Exploiting a 3+1 analysis of the Mars-Simon tensor, conditions are found on a vacuum initial data set ensuring that its development is isometric to a subset of the Kerr spacetime. [ABSTRACT FROM AUTHOR]

This talk is intended for a general audience. A brief history of the two primary physical theories of the twentieth century is presented, and the similarity between the late nineteenth and the early twenty-first centuries is highlighted. In particular, the past and possible future of exact solutions in general relativity are briefly described, and reasons why time is growing short are cited. [ABSTRACT FROM AUTHOR]

The basic idea and some physical implications of nonlinear supersymmetric general relativity(NLSUSY GR) are discussed, which give new insights into the origin of mass and the mysterious relations between the cosmology and the low energy particle physics, e.g., the spontaneous SUSY breaking scale, the cosmological constant, the (dark) energy density of the universe and the neutrino mass. [ABSTRACT FROM AUTHOR]

This paper presents a four-dimensional-space plus time Maxwellian model of gravity for particles that travel at the speed of light in Hyperspace; a Euclidean Relativity space. These particles obey Lorentz invariance when observed in a space-time. The 3-to-4 dimensional interface between sub-elementary electric-charges and mass-charges, both invariant respect to speed in Hyperspace, originates the well known equivalence of mass and energy in space-time. The model reproduces Newtonian gravity plus a large scale correction proportional to the square of the speed that particles have in a space-time. The gravitational force is also calculated in a space-time for which the Schwarzschild’s metric is applicable, producing two additional terms that are effective at very small scale. The large scale correction might be related to observed interplanetary spacecraft flybys anomalies; the small scale corrections might be required for treating strong gravitational anomalies, repulsive gravity or phenomena observed at extremely short distance, which may include the strong nuclear force. [ABSTRACT FROM AUTHOR]

Electromagnetic to gravitational wave converters are characterized by an electrically (and/or magnetically) charged end that couples to the exciting electromagnetic field and a massive end with mechanical quadrupole moment, which couples to the gravitational field. The efficiency of the conversion appears to be very low so that in early theoretical studies it was concluded that whatever system was considered, it would be destroyed by the excitation energy before it could emit detectable gravitational waves. Recent studies are more optimistic by relying on advanced and more sophisticate detectors for defining the threshold of detection. Considering that a Hertz like experiment for gravitational waves also responds to improvements regarding the generator of gravitational waves, to this end we here discuss the possibility that within the nucleus the nuclear holonomy and the corresponding spin-precession coupling may lead to a high-frequency quadrupole spin resonating on high order harmonics of a low-frequency precession excitation frequency, thus increasing the efficiency of the conversion process. Based on conservation laws of holonomy and spin describing the orbital and radial behavior of angular momentum and torque currents in systems with spin-orbit coupling, it is assumed that the two major constraints given by spin conservation (linear) and holonomy (transcendental) could provide for the necessary spin-precession interplay. Because the power emitted as gravitational waves by a given configurations is proportional to the sixth power of the frequency, a precession-spin frequency up-conversion by a factor of 10–1000 (which can be even observed in mechanical model systems) will increase the power emission by 6–18 orders of magnitude for the carrier. A signal phase-frequency modulation could be induced by an additional NMR signal precessing at special magic angles in a modulated magnetic field. Reversely, this system could also act as an active gravitational wave antenna with frequency down-conversion capabilities that could ease the subsequent processing of the signal. [ABSTRACT FROM AUTHOR]

In this study we explore the magnetic mechanism of hypernovae and relativistic jets of long duration gamma ray bursts within the collapsar scenario. This is an extension of our earlier work[1]. We track the collapse of massive rotating stars onto a rotating central black hole using axisymmetric general relativistic magnetohydrodynamic code that utilizes a realistic equation of state and takes into account the cooling associated with emission of neutrinos and the energy losses due to dissociation of nuclei. The neutrino heating is not included. We describe solutions with different black hole rotation, mass accretion rate, and strength of progenitor’s magnetic field. Some of them exhibits strong explosions driven by Poynting-dominated jets with power up to 12×1051 erg s. These jets originate from the black hole and powered via the Blandford-Znajek mechanism. A provisional criterion for explosion is derived. A number of simulation movies can be downloaded from http://www.maths.leeds.ac.uk/serguei/research/movies/anim.html [ABSTRACT FROM AUTHOR]

From a perspective of some 50 years or more, this paper reviews my recall of the early days of scalar-tensor alternatives to standard Einstein general relativistic theory of gravity. Of course, the story begins long before my involvement, going back to the proposals of Nordström in 1914, and that of Kaluza, Klein, et al., a few years later, sol include reviews of these seminal ideas and those that followed in the 1920’s through the 1940’s. This early work concerned the search for a Unified Field Theory, unifying gravity and Electromagnetism, using five dimensional manifolds. This formalism included not only the electromagnetic spacetime vector potential within the five-metric, but also a spacetime scalar as the five-five metric component. Although this was at first regarded more as a nuisance, to be set to a constant, it turned out later that Fierz, Jordan, Einstein and Bergmann noticed that this scalar could be a field, possibly related to the Newtonian gravitational constant. Relatively little theoretical and experimental attention was given to these ideas until after the second world war when Bob Dicke, motivated by the ideas of Mach, Dirac, and others, suggested that this additional scalar, coupled only to the metric and matter, could provide a reasonable and viable alternative to standard Einstein theory. This is the point of my direct involvement with these topics. However, it was Dicke’s prominence and expertise in experimental work, together with the blossoming of NASA’s experimental tools, that caused the explosion of interest, experimental and theoretical, in this possible alternative to standard Einstein theory. This interest has waxed and waned over the last 50 years, and we summarize some of this work. [ABSTRACT FROM AUTHOR]

The gravitational collapse of a star is an important issue both for general relativity and astrophysics, which is related to the well known “frozen star” paradox. Following the seminal work of Oppenheimer and Schneider (1939), we present the exact solution for two dust shells collapsing towards a pre-existing black hole. We find that the inner region of the shell is influenced by the property of the shell, which is contrary to the result in Newtonian theory and and the clock inside the shell becomes slower as the shell collapses towards the pre-existing black hole. This result in principle may be tested experimentally if a beam of light travels across the shell. We conclude that the concept of the “frozen star” should be abandoned, since matter can indeed cross a black hole’s horizon according to the clock of an external observer. Since matter will not accumulate around the event horizon of a black hole, we predict that only gravitational wave radiation can be produced in the final stage of the merging process of two coalescing black holes. Our results also indicate that for the clock of an external observer, matter, after crossing the event horizon, will never arrive at the “singularity” (i.e. the exact center of the black hole). [ABSTRACT FROM AUTHOR]

We present numerical simulations of axisymmetric magnetised massive tori around rotating black holes taking into account the energy losses due to emission of neutrinos. A realistic equation of state is used which takes into account the energy losses due to dissociation of nuclei. The heating due to neutrino-antineutrino annihilation is not included. We study the cases of optically thick, semitransparent, and optically thin to neutrino disks. We show that neutrino cooling does not change significantly the structure of accretion flow and the total energy release. The time scale of accretion is set by the torus angular momentum. Due to the lack of magnetic dynamo in our calculations, it is the initial strength of magnetic field and its topology that determine the process of jet formation and its energetics. Extrapolation of our results gives the total energy released in the jet ∼1052 erg. This is sufficient to explain the hypernovae explosions associated with GRB 980425 and GRB 030329. [ABSTRACT FROM AUTHOR]

Interest in relativistic irreversible thermodynamics has been revived due to several new experiments, such as relativistic heavy ion collisions, now feasible with modern technology. Also, old unsolved problems such as the derivation of a causal heat equation have witnessed novel approaches. This work presents an account of the controversy that arises when one wants to include heat in relativistic irreversible thermodynamics formalisms. An experiment which may throw light on this problem is emphasized. [ABSTRACT FROM AUTHOR]

We discuss two examples of geometries within the framework of non-commutative geometry. Both geometries are of interest due to their appearance in General Relativity and other fields in physics. [ABSTRACT FROM AUTHOR]

The aim of this work is to review the concepts of time in quantum mechanics and general relativity to show their incompatibility. We show that the absolute character of Newtonian time is present in quantum mechanics and also partially in quantum field theories which consider the Minkowski metric as the background spacetime. We discuss the problems which this non-dynamical concept of time causes in general relativity that is characterized by a dynamical spacetime. [ABSTRACT FROM AUTHOR]

A large scale survey for pulsars and transients is being conducted at the Arecibo Observatory using the Arecibo L-band Feed Array (ALFA). Data acquisition so far has been with correlation spectrometers that analyze a 0.1 GHz bandwidth at 1.4 GHz. The 256 frequency channels limit dispersion smearing to 1.2 ms at DMmax = 103 pc cm-3 while the sampling interval of 64 μs equals the dispersion smearing at DM∼54 pc cm-3, providing high sensitivity to millisecond pulsars with standard periods out to implied distances of several kpc at low Galactic latitudes. In early 2008, we will use a new set of polyphase filter bank systems that provide the same time and frequency resolutions but over ALFA's full 0.3 GHz bandwidth. Currently the survey covers sky positions within 5° of the Galactic plane that are reachable with Arecibo. Preliminary results are given for some of the discoveries made so far, which include millisecond pulsars, a relativistic binary pulsar, a likely counterpart of a Compton GRO/EGRET gamma-ray source, and transient pulsars (including ‘RRATs”). We discuss the methodology of the survey, which includes archival of raw survey data at the Cornell Center for Advanced Computing and processing at distributed sites. The survey and follow up observations, which include timing observations, multiwavelength searches for orbital companions in the case of binary pulsars, etc. are organized through the Pulsar-ALFA (PALFA) Consortium. We expect the Galactic plane survey to continue until at least 2010, most likely involving multiple passes on each sky position to optimize detection of variable sources. The ALFA system will also be used to survey intermediate Galactic latitudes for millisecond pulsars, relativistic binaries with large systemic velocities, and runaway pulsars that will escape the Galaxy. [ABSTRACT FROM AUTHOR]

The new techniques for high speed space travel, capable of overcoming current limitations, require the existence of at least one additional dimension for defining flight trajectories. This requirement combines with the already known possibility of using high-frequency gravitational waves for inducing motion. An additional large space dimension has been already found in the Euclidean formulation of Relativity within the Hyperspace paradigm, the finding does not require any new fundamental discovery and can be exploited with the current understanding of physics. The next step consists of analyzing how the traditional formulation of gravitational waves merges with the Hyperspace formalism. Specifically, the traditional relativistic analysis forces gravitational waves to propagate in three spatial dimensions and they are not allowed to propagate through time, treating them like electromagnetic waves. On the other hand, according to the Schwarzschild metric, gravity propagates in four dimensions in the Hyperspace. Our objective is to discuss the possibility that some important features of gravitational waves are still largely overlooked and these features might involve accessibility to the proper time dimension for advanced propulsion schemes, observation and communications. [ABSTRACT FROM AUTHOR]

It has been well known that in the point of view of a distant observer, all in-falling matter to a black hole (BH) will be eventually stalled and “frozen” just outside the event horizon of the BH, although an in-falling observer will see the matter falling straight through the event horizon. Thus in this “frozen star” scenario, as distant observers, we could never observe matter falling into a BH, neither could we see any “real” BH other than primordial ones, since all other BHs are believed to be formed by matter falling towards singularity. Here we first obtain the exact solution for a pressureless mass shell around a pre-existing BH. The metrics inside and interior to the shell are all different from the Schwarzschild metric of the enclosed mass, meaning that the well-known Birkhoff Theorem can only be applied to the exterior of a spherically symmetric mass. The metric interior to the shell can be transformed to the Schwarzschild metric for a slower clock which is dependent of the location and mass of the shell; we call this Generalized Birkhoff Theorem. Another result is that there does not exist a singularity nor event horizon in the shell. Therefore the “frozen star” scenario is incorrect. We also show that for all practical astrophysical settings the in-falling time recorded by an external observer is sufficiently short that future astrophysical instruments may be able to follow the whole process of matter falling into BHs. The distant observer could not distinguish between a “real” BH and a “frozen star”, until two such objects merge together. It has been proposed that electromagnetic waves will be produced when two “frozen stars” merge together, but not true when two “real” bare BHs merge together. However gravitational waves will be produced in both cases. Thus our solution is testable by future high sensitivity astronomical observations. [ABSTRACT FROM AUTHOR]

We present the geometrical properties of the region where the vacuum polarization process occur in the Kerr-Newman spacetime. We find that the shape of the region can be ellipsoid-like or torus-like depending on the charge of the black hole. [ABSTRACT FROM AUTHOR]

In this talk we discuss several properties of the Mixmaster model. The ADM (Arnowitt-Deser-Misner) Hamiltonian framework is here adopted, and the dynamics reduced to the physical degrees of freedom. On the quasi-classical level, the Hamilton-Jacobi equation and the mechanical-statistical point of view are discussed in some detail; the operator-ordering to be used on the quantum level is also fixed. A full description of the Schroedinger dynamics is then provided, and the eigenfunctions, the energy levels and the properties of the spectrum are analyzed both analytically and numerically. [ABSTRACT FROM AUTHOR]

The gravitational wave detector VIRGO is in the final commissioning phase and some preliminary data has already been acquired. The aim of VIRGO is to directly detect gravitational waves emitted by compact objects at the time of coalescence and by other astrophysical sources. Here we report on the present sensitivity for detecting these sources and what we will achieve in the near future. We also discuss some details of our data analysis methods and we show some preliminary results related to the fraction of the Universe that we can observe. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Although there is general agreement that a removal of classical gravitational singularities is not only a crucial conceptual test of any approach to quantum gravity but also a prerequisite for any fundamental theory, the precise criteria for non-singular behavior are often unclear or controversial. Often, only special types of singularities such as the curvature singularities found in isotropic cosmological models are discussed and it is far from clear what this implies for the very general singularities that arise according to the singularity theorems of general relativity. In these lectures we present an overview of the current status of singularities in classical and quantum gravity, starting with a review and interpretation of the classical singularity theorems. This suggests possible routes for quantum gravity to evade the devastating conclusion of the theorems by different means, including modified dynamics or modified geometrical structures underlying quantum gravity. The latter is most clearly present in canonical quantizations which are discussed in more detail. Finally, the results are used to propose a general scheme of singularity removal, quantum hyperbolicity, to show cases where it is realized and to derive intuitive semiclassical pictures of cosmological bounces. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Weyl’s Gauge Principle of 1929 has been used to show that a five-dimensional gauge field wherein the fifth dimension is conserved in the same mathematical sense as the conservation of mass embeds a four-dimensional hyper surface into the five dimensional manifold. The equations specifying the geometry of the embedded hyper surface are similar in form to Einstein’s field equations of his General Theory of Relativity. These field equations become Einstein’s field equations when one takes the fifth dimension to be mass density. This means the predictions of Einstein’s General Theory may be achieved in two different ways. One by using Einstein’s method and the other by using a five dimensional manifold of space, time and mass density while restricting mass to be conserved. The five dimensional gauge fields associated with these phenomena are converted into a four dimensional curved hyper surface by the conservation of mass. The mathematical equivalence of the two methods provides the justification to seek what predictions might be made considering the five dimensional gauge field wherein the electromagnetic fields are inductively coupled to the gauge gravitational field. This presentation will present the logic showing how Einstein’s General Theory of Relativity may be derived from the five dimensional manifold using the conservation of mass. Comparison of predictions of perihelion advance by using the view from the embedded four-dimensional hyper surface and from the five dimensional manifold shows the equivalence of the two methods of viewing physical phenomena. The inductive coupling between the electromagnetic and gravitational fields may be given experimental support by showing that predictions of the Earth’s magnetic moment due to its spinning gravitational mass is within 7% of the experimentally measured value. Such an inductively coupling between the gravitational gauge field and the electromagnetic gauge field provides an opportunity to seek predictions of the resulting five dimensional wave equations. Whereas in Maxwellian electromagnetism there are two, coupled, vector wave equations in the five dimensional gauge field there are three, coupled, vector wave equations that are also coupled to a scalar wave equation. The presentation will discuss the resulting transverse and longitudinal solutions to this system of wave equations. It will show that the inductive coupling with the gravitational field provides a very weak gravitational component to the transverse waves. It will also show that the longitudinal wave solutions may be independent of the transverse solutions and that the longitudinal solutions consist of only electric and gravitational vector components with an accompanying scalar wave. Longitudinal electrogravitic waves do not interact with the propagation medium as do transverse waves and make good candidates for space communication. Not only will longitudinal waves pass through intervening material, but they may be made very directive and, thereby, avoid a 1/r2 loss. The presentation will also present an antenna design for converting transverse electromagnetic waves into longitudinal electrogravitic waves for using current transmitting laser communication equipment and the reciprocal antenna design for converting longitudinal waves back into transverse waves to use current receivers. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

In the Theory of Relativity time is treated as a dimension. This property of time has never been completely understood and accepted because we instinctively perceive time only as a running parameter. In recent developments of the Theory of Relativity, it has been proposed to apply a coordinate transformation by which the four coordinates all acquire the dimension of space, with time defined as a running parameter related to the speed of light. The transformation formally defines the Four-Space or, using a common word for spaces with more than three dimensions, the “Hyperspace”. Under this paradigm, the entire story of the Universe is similar to a set of nested trajectories in which our “reality” develops along a membrane moving through the nested trajectories at the speed of light. The new paradigm implies the existence of multiple “parallel” membranes, or parallel local universes or multiverses and “crossing” membranes, or “orthogonal” local Universes, which do not emerge from the plain Theory of Relativity. In the Hyperspace everything normally travels at the speed of light, but a localized strong gravitational field, which creates a propagation speed discontinuity in Hyperspace, may allow travel to different local universes or Faster Than Light (FTL) travel within the same local universe. The collision or focusing of gravitational waves can produce effects comparable to those of short-lived black holes that can be projected into the Hyperspace to produce the required speed modification. Well known optical effects and four-dimensional rotation may also find application to Hyperspace travel. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Weyl’s scale invariance is introduced as an additional local symmetry in the standard model of electroweak interactions. An inevitable consequence is the introduction of general relativity coupled to scalar fields à la Dirac and an additional vector particle we call the Weylon. Once Weyl’s scale invariance is broken, the phenomenon (a) generates Newton’s gravitational constant GN and (b) triggers the conventional spontaneous symmetry breaking mechanism that results in masses for all the fermions and bosons. The scale at which Weyl’s scale symmetry breaks is of order Planck mass. If right-handed neutrinos are also introduced, their absence at present energy scales is attributed to their mass which is tied to the scale where scale invariance breaks. Some implications of these ideas are noted in grand unification based on the gauge symmetry SU(5). © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

We review the basics of a newly developed mean field theory of relativistic gravitation. A particularly simple coarse graining of the Schwarzschild space-time is presented as an example. This example is then used to discuss current and near future observations of Sgr A*. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We present a general study of the dynamical properties of Anisotropic Bianchi Universes in the context of Einstein General Relativity. Integrability results using Kovalevskaya exponents are reported and connected to general knowledge about Bianchi dynamics. Finally, dynamics toward singularity in Bianchi type VIII and IX universes are showed to be equivalent in some precise sence. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Cosmic topology has entered a new era of experimental tests since accurate maps of the Cosmic Microwave Background radiation (CMB) are available. Various deviations from the concordance Λ-CDM flat infinite universe model hint at a possible non-trivial topology for the shape of space. A finite universe with the topology of the Poincaré dodecahedral spherical space fits remarkably well the data and is a good candidate for explaining both the local curvature of space and the large angle anomalies in the temperature power spectrum. Such a model of a “small universe”, the volume of which would represent only about 80% the volume of the observable universe, offers an observational signature in the form of a predictable topological lens effect on one hand, and rises new issues on the physics of the early universe on the other hand. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Recently, a relativistic gravitation theory has been proposed by Bekenstein that gives the Modified Newtonian Dynamics (or MOND) in the weak acceleration regime. The theory is based on three dynamic gravitational fields and succeeds in explaining a large part of extragalactic and gravitational lensing phenomenology without invoking dark matter. In this work we consider the strong gravity regime of TeVeS. We study spherically symmetric, static and vacuum spacetimes relevant for a non-rotating black hole or the exterior of a star. Two branches of solutions are identified: in the first the vector field is aligned with the time direction while in the second the vector field has a non-vanishing radial component. We show that in the first branch of solutions the β and γ PPN coefficients in TeVeS are identical to these of general relativity (GR) while in the second the β PPN coefficient differs from unity violating observational determinations of it (for the choice of the free function F of the theory made in Bekenstein’s paper). For the first branch of solutions, we derive analytic expressions for the physical metric and discuss their implications. Applying these solutions to the case of black holes, it is shown that they violate causality (since they allow for superluminal propagation of metric, vector and scalar waves) in the vicinity of the event horizon and/or that they are characterized by negative energy density carried by the fields. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Three well-known problems (perihelion advance, photon deflection, radar echo delay) are studied in the framework of Zatrikean Pregeometry. The results differ less than 0.1% from those of General Relativity. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In this talk I review recent advances in cosmic topology since it has entered a new era of experimental tests. High redshift surveys of astronomical sources and accurate maps of the Cosmic Microwave Background radiation (CMB) are beginning to hint at the shape of the universe, or at least to limit the wide range of possibilities. Among those possibilites are surprising “wrap around” universe models in which space, whatever its curvature, may be smaller than the observable universe and generate topological lensing effects on a detectable cosmic scale. In particular, the recent analysis of CMB data provided by the WMAP satellite suggest a finite universe with the topology of the Poincaré dodecahedral spherical space. Such a model of a “small universe”, the volume of which would represent only about 80% the volume of the observable universe, offers an observational signature in the form of a predictable topological lens effect on one hand, and rises new issues on the early universe physics on the other hand. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The evolution of the methods used to find solutions of Einstein’s field equations during the last 100 years is described. Early papers used assumptions on the coordinate forms of the metrics. Since the 1950s more invariant methods have been deployed in most new papers. The uses to which the solutions found have been put are discussed, and it is shown that they have played an important role in the development of many aspects, both mathematical and physical, of general relativity. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In special relativity the chronogeometrical structure is absolute and there is no notion of instantaneous 3-space: distant clock synchronization is based on a convention, which changes going from inertial to non-inertial frames. On the contrary in Einstein general relativity the metric tensor has a double role: 1) it is the mediator of the gravitational interaction; 2) it determines the dynamical chronogeometrical structure of spacetime. As a consequence, it “teaches relativistic causality” to to every other field with the following implications: a) the conventions for distant clock synchronization in non-inertial frames are dynamically determined; b) the 8 arbitrary gauge variables hidden in the metric tensor describe “inertial effects” in non-inertial frames; c) the Dirac observables of the gravitational field describe “tidal effects” in non-inertial frames. A Hamiltonian reading of Bergmann-Komar intrinsic pseudo-coordinates, in connection with Einstein’s Hole Argument, leads to a identification of the notions of “spacetime” and “gravitational field”, which must be taken into account in any approach to quantum gravity. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The double pulsar system J0737-3039A/B is one of the most intriguing pulsar discoveries of the last decade. This binary system, with an orbital period of only 2.4-hr, provides a truly unique laboratory for relativistic gravity. Its discovery enhances of about an order of magnitude the estimate of the merger rate of double neutron stars systems, opening new possibilities for the current generation of gravitational wave detectors. In this contribution we summarize the present results and look at the prospects of future observations. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Implementation of faster-than-light (FTL) interstellar travel via traversable wormholes, warp drives, or other spacetime modification schemes generally requires the engineering of spacetime into very specialized local geometries. The analysis of these via Einstein’s General Theory of Relativity (GTR) field equations plus the resultant equations of state demonstrate that such geometries require the use of “exotic” matter in order to induce the requisite FTL spacetime modification. Exotic matter is generally defined by GTR physics to be matter that possesses (renormalized) negative energy density, and this is a very misunderstood and misapplied term by the non-GTR community. We clear up this misconception by defining what negative energy is, where it can be found in nature, and we also review the experimental concepts that have been proposed to generate negative energy in the laboratory. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The canonical form of the Alcubierre warp drive metric is considered to gain insight into the mathematical mechanism triggering the effect. A parallel with the Chung-Freese spacetime metric is drawn to demonstrate that the spacetime expansion boost can be considered a 3 + 1 on-brane simplification for higher dimensional geometric effects. The implications for baryonic matter of higher dimensional spacetime, in conjunction with the Alcubierre metric, are used to illustrate an equation of state for dark energy. Finally, this combined model will then be used to outline a theoretical framework for negative pressure (an alternative to negative energy) and a conceptual lab experiment is described. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The Schwarzschild solution is used to find the exact relativistic motion of a payload in the gravitational field of a mass moving with constant velocity. At radial approach or recession speeds faster than 3-1/2 times the speed of light, even a small mass gravitationally repels a payload. At relativistic speeds, a suitable mass can quickly propel a heavy payload from rest nearly to the speed of light with negligible stresses on the payload. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]