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The article focuses on "The Great Historical Clock of America," an immense clock from 1890 exhibited in the Smithsonian's National Museum of American History. Topics include the clock's dimensions, intricate decorations depicting scenes from U.S. history, and its significance as an uncommon object with a life history that reveals connections between people and things. The article explores the concept of object biography, tracing the clock's journey through time and space.

It has been shown that the theory of relativity can be applied physically to the functioning brain, so that the brain connectome should be considered as a four-dimensional spacetime entity curved by brain activity, just as gravity curves the four-dimensional spacetime of the physical world. Following the most recent developments in modern theoretical physics (black hole entropy, holographic principle, AdS/CFT duality), we conjecture that consciousness can naturally emerge from this four-dimensional brain connectome when a fifth dimension is considered, in the same way that gravity emerges from a 'flat' four-dimensional quantum world, without gravitation, present at the boundaries of a five-dimensional spacetime. This vision makes it possible to envisage quantitative signatures of consciousness based on the entropy of the connectome and the curvature of spacetime estimated from data obtained by fMRI in the resting state (nodal activity and functional connectivity) and constrained by the anatomical connectivity derived from diffusion tensor imaging. [ABSTRACT FROM AUTHOR]

We review some semantical aspects of probability bounds from Boole's "conditions on possible experience" violated by quantum mechanics. We also speculate about emerging space-time categories as an epiphenomenon of quantization and the resulting breakdown of relativity theory by non-unitary and non-linear processes. [ABSTRACT FROM AUTHOR]

We explore the tripartite entropic uncertainty and genuine tripartite quantumness of Dirac fields in the background of the Garfinkle–Horowitz–Strominger (GHS) dilation space-time. It is interesting to note that Hawking radiation leads to the decay of quantum nonlocality in the physically accessible region while preserving its total coherence. More importantly, it demonstrates an intrinsic trade-off relationship between the coherences of physically accessible and inaccessible regions. Moreover, we examine the effect of Hawking radiation on entropy-based measured uncertainty and find that stronger Hawking radiation causes the uncertainty in physically accessible regions to increase while decreasing the uncertainty in physically inaccessible regions. Therefore, our investigations may be beneficial to a better understanding of the system's quantumness in a curved space-time. Combining relativity theory with quantum information science offers new avenues for comprehending the information paradoxes involving black holes. [ABSTRACT FROM AUTHOR]

The main aim of this study is to provide new academic knowledge and at the same time create a modern political awareness to free the mind and stereotypical behavior from the axioms and fallacious perceptions that are not valid and, actually do not exist. On the other hand, this study contributes mainly to the field of political theory, and international relations, by utilizing some specializations and scientific methods in other disciplines such as physics, anthropology, sociology, and philosophy. This critical study examines the interaction of Shi’a in Kuwait with the political event from 1896 to 2020. Furthermore, the study provides philosophical reviews of the role of reason in intellectual perceptions and practical behavior. In this context, the study reviewed the political, philosophical, and juristic ideas and perceptions of Shi’a clerics related to the role of mind. Since Kuwait was cast away from the Ottoman Empire and became an independent political entity after Sheikh Mubarak Al-Sabah held the power in 1896, the Shi’a involvement in internal politics was also reviewed. To arrive at a scientific analysis of the Shi’a political mind problematics in particular and the political mind in Kuwait in general, some of the scientific views, concepts, and theories of relativity and spacetime were utilized within the frameworks of philosophical and political literature. This study, likewise, investigates some of the significant historical events that were not carefully inspected before, as it should be deserved. Besides, the study determined several problems that explain the predicaments of the Shi’a political mind. [ABSTRACT FROM AUTHOR]

In order to study the dynamics of spinning particles in R-Minkowski space–time, first we have used the Bhabha–Corben model to describe how a spinning particle behave in a uniform electromagnetic field. Then, to extend the Mathisson–Papapetrou equations to R-Minkowski space–time, that correspond to de Sitter space–time given by a conformally flat metric, it was necessary to determine the Killing vectors, which allowed us to find the equations of motion that describe the dynamics of spinning particles. [ABSTRACT FROM AUTHOR]

Quasilocal definitions of stress-energy–momentum—that is, in the form of boundary densities (in lieu of local volume densities) — have proven generally very useful in formulating and applying conservation laws in general relativity. In this Essay, we take a basic look into applying these to cosmology, specifically using the Brown–York quasilocal stress-energy–momentum tensor for matter and gravity combined. We compute this tensor and present some simple results for a flat FLRW spacetime with a perfect fluid matter source. We emphasize the importance of the vacuum energy, which is almost universally underappreciated (and usually "subtracted"), and discuss the quasilocal interpretation of the cosmological constant. [ABSTRACT FROM AUTHOR]

Cosmic censorship is known to fail in some well-controlled phenomena, calling into question the predictive power of General Relativity and opening up the possibility of observing Planck-scale physics. We propose that the cosmic censorship conjecture can be amended so that its spirit prevails. Naked singularities that, classically, have zero mass are allowed. Physically, these are Planck-sized "black holes", which evaporate in a few Planck times. General Relativity fails only for a tiny interval in time, to then quickly regain control in a Miltonian evolution that returns us to the predictive paradise of Einstein's equations. If this refinement of the conjecture is correct, then, even though Nature does allow to expose breakdowns in the smooth fabric of spacetime, it limits them to a mostly harmless minimum. [ABSTRACT FROM AUTHOR]

This article introduces a new field theory formulation. The new field theory formulation recognizes vector continuity as a general principle and begins with a field that satisfies vector continuity equations. Next, independent of the new formulation, this article introduces a new space-time adjustment. Then, we solve the one-body gravitational problem by applying the space-time adjustment to the new field theory formulation. With the space-time adjustment, the new formulation predicts precisely the same precession of Mercury and the same bending of light as general relativity. The reader will find the validating calculations to be simple. The equations of motion that govern the orbital equations are in terms of Cartesian coordinates and time. An undergraduate college student, with direction, can perform the validations. [ABSTRACT FROM AUTHOR]

For mathematical convenience initial data sets in numerical relativity are often taken to be conformally flat. Employing the dual-foliation formalism, we investigate the physical consequences of this assumption. Working within a large class of asymptotically flat spacetimes we show that the ADM linear momentum is governed by the leading Lorentz part of a boost even in the presence of supertranslation-like terms. Following up, we find that in spacetimes that are asymptotically flat, and admit spatial slices with vanishing linear momentum that are sufficiently close to conformal flatness, any boosted slice can not be conformally flat. Consequently there are no conformally flat boosted slices of the Schwarzschild spacetime. This confirms the previously anticipated explanation for the presence of junk-radiation in Brandt–Brügmann puncture data. [ABSTRACT FROM AUTHOR]

In this work, we provide several insights which are related to the physical origins and the mathematical formulation of the principle of material frame-indifference in solid mechanics. The salient feature of the present approach relies crucially on the concrete understanding that when one models the ambient space as a rigid Euclidean space—one with a constant metric—misses important geometrical information; this information is related to the spacetime structure, the possible spacetime transformations and the spacetime–matter interaction. Upon abandoning this point of view and considering the ambient space as a flat manifold, we can see that material frame-indifference is a spacetime property which follows naturally from a physical postulate, namely that of Leibniz equivalence. We also analyze the connection which exists between material frame-indifference and relativity principles; this analysis vindicates Noll's initial intuition to call the principle "principle of isotropy of space". Finally, upon considering the spatial metric as a dynamical object which incorporates the deformation field, we present a formal introduction to the concept of general covariance in a constitutive theory. [ABSTRACT FROM AUTHOR]

In this paper, we employ the Karmarkar condition to model a spherically symmetric radiating star undergoing dissipative gravitational collapse within the framework of classical general relativity. The collapse ensues from an initial static core satisfying the Karmarkar condition in isotropic coordinates and proceeds nonadiabatically by emitting energy in the form of a radial heat flux to the exterior Vaidya spacetime. We show that the dynamical nature of the collapse is sensitive to the initial static configuration that inherently links the embedding to the final remnant. Our model considered several physical tests on how an initially static stellar structure onset to a radiative collapse. [ABSTRACT FROM AUTHOR]

The mass of a system in general relativity cannot be defined locally. Thus, one defines mass at quasilocal level. There are many definitions of quasilocal mass. One of them is the Hawking mass. In this paper, we determine the Hawking mass for ellipsoidal 2-surface for a non-Schwarzschild spacetime. In order to do this, we first determine a null tetrad and then compute the Hawking mass. The results are presented graphically also. [ABSTRACT FROM AUTHOR]

Leibniz Equivalence is a principle of applied mathematics that is widely assumed in both general relativity textbooks and in the philosophical literature on Einstein's hole argument. In this article, I clarify an ambiguity in the statement of this Leibniz Equivalence, and argue that the relevant expression of it for the hole argument is strictly false. I then show that the hole argument still succeeds as a refutation of manifold substantivalism; however, recent proposals that the hole argument is undermined by principles of representational equivalence do not fare so well. [ABSTRACT FROM AUTHOR]

The Hole Argument was originally formulated by Einstein and it haunted him as he struggled to understand the meaning of spacetime coordinates in the context of the diffeomorphism invariance of general relativity. This argument has since been put to philosophical use by Earman and Norton (Br J Philos Sci 515–525, 1987) to argue against a substantival conception of spacetime. In the present work I demonstrate how Earman and Norton's Hole Argument can be extended to exclude everything and not merely substantival manifolds. These casualties of the hole demonstrate that the Hole Argument hinges essentially on our notion of determinism and not on the diffeomorphic freedom of general relativity. Just as Earman and Norton argue that we should not let our metaphysics run roughshod over the structure of our physical theories, so I will argue that, in particular, we should not uncritically allow our metaphysics to dictate what our physical theories must determine. The central conviction which drives the arguments of this paper is that deterministic theories are not required to determine for future moments what they cannot determine for any present or past moments. I provide two arguments to the effect that a physically informed notion of determinism does not require general relativity to determine substantival facts. Consequently the Hole Argument cannot be used against substantival spacetime. The position that I advocate is an instance of "sophisticated determinism." [ABSTRACT FROM AUTHOR]

I apply homotopy type theory (HoTT) to the hole argument as formulated by Earman and Norton. I argue that HoTT gives a precise sense in which diffeomorphism-related Lorentzian manifolds represent the same spacetime, undermining Earman and Norton's verificationist dilemma and common formulations of the hole argument. However, adopting this account does not alleviate worries about determinism: general relativity formulated on Lorentzian manifolds is indeterministic using this standard of sameness and the natural formalization of determinism in HoTT. Fixing this indeterminism results in a more faithful mathematical representation of general relativity as used by physicists. It also gives a substantive notion of general covariance. [ABSTRACT FROM AUTHOR]

ISIM(2) symmetry group of Cohen and Glashow's very special relativity is unstable with respect to small deformations of its underlying algebraic structure, and according to Segal's principle cannot be a true symmetry of nature. However, like special relativity, which is a very good description of nature, thanks to the smallness of the cosmological constant, which characterizes the deformation of the Poincaré group, the very special relativity can also be a very good approximation, thanks to the smallness of the dimensionless parameter characterizing the deformation of ISIM(2). [ABSTRACT FROM AUTHOR]

I present an argument against a relational theory of spacetime that regards spacetime as a 'structural quality of the field'. The argument takes the form of a trilemma. To make the argument, I focus on relativistic worlds in which there exist just two fields, an electromagnetic field and a gravitational field. Then there are three options: either spacetime is a structural quality of each field separately, both fields together, or one field but not the other. I argue that the first option founders on a problem of geometric coordination and that the second and third options collapse into substantivalism. In particular, on the third option it becomes clear that the relationalist's path to Leibniz equivalence is no simpler or more straightforward than the substantivalist's. 1 Introduction 2 Background 2.1 Relational theories of spacetime 2.2 Brief remarks on general relativity 3 First Horn: Geometric Coordination 4 Second Horn: Problems of Coincidence 5 Third Horn: General Relativity and Gauge 5.1 Preventing collapse 5.2 The revised shift argument 6 Conclusion [ABSTRACT FROM AUTHOR]

We point out a fundamental problem that hinders the quantization of general relativity: quantum mechanics is formulated in terms of systems, typically limited in space but infinitely extended in time, while general relativity is formulated in terms of events, limited both in space and in time. Many of the problems faced while connecting the two theories stem from the difficulty in shoe-horning one formulation into the other. A solution is not presented, but a list of desiderata for a quantum theory based on events is laid out. [ABSTRACT FROM AUTHOR]

This paper looks at the relationship between spacetime functionalism and Harvey Brown's dynamical relativity. One popular way of reading and extending Brown's programme in the literature rests on viewing his position as a version of relationism. But a kind of spacetime functionalism extends the project in a different way, by focussing on the account Brown gives of the role of spacetime in relativistic theories. It is then possible to see this as giving a functional account of the concept of spacetime which may be applied to theories that go beyond relativity. This paper explores the way in which both the relationist project and the functionalist project relate to Brown's work, despite being incompatible. Ultimately, these should not be seen as two conflicting readings of Brown, but two different directions in which to take his project. [ABSTRACT FROM AUTHOR]

As Harvey Brown emphasizes in his book Physical Relativity , inertial motion in general relativity is best understood as a theorem, and not a postulate. Here I discuss the status of the "conservation condition", which states that the energy-momentum tensor associated with non-interacting matter is covariantly divergence-free, in connection with such theorems. I argue that the conservation condition is best understood as a consequence of the differential equations governing the evolution of matter in general relativity and many other theories. I conclude by discussing what it means to posit a certain spacetime geometry and the relationship between that geometry and the dynamical properties of matter. [ABSTRACT FROM AUTHOR]

This paper is aimed to set up a thin-shell gravastar model and address its physically accepted features in the background of noncommutative geometry. For this purpose, we have considered the cylindrically symmetric interior metric matched with suitable noncommutative exterior geometry using Israel boundary conditions. The stability of this thin-shell as well as thermodynamical stability is then explored under linear perturbations around the throat. We have found the stable regions near the horizon with some specific values of the involved parameters. [ABSTRACT FROM AUTHOR]

Wormholes (WHs) are a solution for General Relativity field equations which characterize a passage or tunnel that connects two different regions of spacetime and is filled by some sort of exotic matter that does not satisfy the energy conditions. On the other hand, it is known that in extended theories of gravity, the extra degrees of freedom once provided may allow the energy conditions to be obeyed and, consequently, the matter content of the WH to be nonexotic. In this work, we obtain, as a novelty in the literature, solutions for charged WHs in the f (R , T) -extended theory of gravity. We show that the presence of charge in these objects may be a possibility to respect some stability conditions for their metric. Also, remarkably, the energy conditions are respected in the present approach. In addition, we argue that our framework can be very useful to study the possibility of evolving (2 + 1) and (3 + 1) -dimensional WH spacetime within the context of nonlinear electrodynamics, which open a new window to probe the physical quantities in a WH-type solution. [ABSTRACT FROM AUTHOR]

Abstract Background independence begins life as an informal property that a physical theory might have, often glossed as 'doesn't posit a fixed spacetime background'. Interest in trying to offer a precise account of background independence has been sparked by the pronouncements of several theorists working on quantum gravity that background independence embodies in some sense an essential discovery of the General Theory of Relativity, and a feature we should strive to carry forward to future physical theories. This paper has two goals. The first is to investigate what a world must be like in order to be truly described by a background independent theory given extant accounts of background independence. The second is to argue that there are no non-empirical reasons to be more confident in theories that satisfy extant accounts of background independence than in theories that don't. The paper concludes by drawing a general moral about a way in which focussing primarily on mathematical formulations of our physical theories can adversely affect debates in the metaphysics of physics. Highlights • Investigates the metaphysics of extant accounts of background independence. • Argues that there's no apriori reason to favor background independent theories. • Draws a general moral about the role of mathematics in the metaphysics of physics. [ABSTRACT FROM AUTHOR]

Abstract In this paper we analyze the energy levels of a charged scalar particle placed in the static cosmic string spacetime, under the action of a uniform magnetic field parallel to the string, in the context of the semi-classical approach of the rainbow gravity. Firstly, we focus on the non-relativistic regime by solving the corresponding Schrödinger equation, following by a complete relativistic treatment of the problem in which we considered the Klein–Gordon equation. In both cases we find exact expressions for the Landau levels in terms of the rainbow functions, used to characterize a rainbow gravity model. In order to achieve the results of this paper we considered three different rainbow gravity models mostly used in the literature and compare the resulting modifications in the Landau levels with the standard case, namely without rainbow gravity. [ABSTRACT FROM AUTHOR]

We have studied the effect of energy-dependent potentials for the relativistic spinning particle using the formalism for supersymmetric path integrals. That leaves behind a new normalization of wave function, which is examined via the Dirac equation and can be confirmed by Feynman's path integral method. Based on two important examples, Coulomb and Harmonic oscillator potentials, we find that the frequency and the Coulomb's constant are dependent on spectral parameters. The propagator is calculated and the energy eigenvalues with their corresponding eigenfunctions are deduced. [ABSTRACT FROM AUTHOR]

There are two classes of topologies most often placed on the space of Lorentz metrics on a fixed manifold. As I interpret a complaint of Geroch [Relativity (Plenum, 1970), p. 259 and Gen. Relativ. Gravitation 2, 61 (1971)], however, neither of these standard classes correctly capture a notion of global spacetime similarity. In particular, Geroch presents examples to illustrate that one, the compact-open topologies, in general seems to be too coarse, while another, the open (Whitney) topologies, in general seems to be too fine. After elaborating further the mathematical and physical reasons for these failures, I then construct a topology that succeeds in capturing a notion of global spacetime similarity and investigate some of its mathematical and physical properties. [ABSTRACT FROM AUTHOR]

Abstract In 2018, the Congress of the Philippines is expected to pass the Philippine Space Development Act , leading to the adoption of the first national space policy in the country and the establishment of the Philippine Space Agency (or PhilSA). This historic event is the final outcome of a long process involving various stakeholders in the Philippines from government, academia and industry. This article provides the first comprehensive history of this process from its inception in the late 20th century until now, with a specific focus on its acceleration since 2013. It also investigates the future expectations of the national space development program, in particular regarding the development of a local space industry. Apart from solely describing the history of the Philippines, this paper presents more generally the case of a developing country willing to gain a foothold in space. In comparison with existing literature on space development programs focusing exclusively on rich western countries or powerful emerging nations, this paper provides other developing countries with highly valuable information by describing such a transparent, balanced and promising initiative as the Philippine space development program. Highlights • The Philippine Space Policy is balanced and perfectly fits the needs of the country. • The process of developing the Philippine space policy can inspire other countries. • Private sector's involvement is crucial for the success of the future space program. • The Filipino space policy's parliamentary approval is expected for late 2018. • Initiating a space program is feasible and recommended for developing countries. [ABSTRACT FROM AUTHOR]

In the following paper, the author will try to test the meaning of the transcendental approach in respect of the inner changes implied by the idea of quantum gravity. He will firstly describe the basic methodological Kant’s aim, viz. the grounding of a meta-science of physics as the a priori corpus of physical knowledge. After that, he will take into account the problematic physical and philosophical relationship between the theory of relativity and the quantum mechanics; in showing how the elementary ontological and epistemological assumptions of experience result to be changed within them, he will also show the further modifications occurred in the development of the loop quantum gravity. He will particularly focus on the tough problem of the relationship space-matter, in order to settle the decisive question about the possibility of keeping a transcendental approach in the light of quantum gravity. He will positively answer by recalling Cassirer’s theory of the invariants of experience, although he will also add some problematic issues arising from the new physical context. [ABSTRACT FROM AUTHOR]

The bundles suitable for a description of higher-spin fields can be built in terms of a 2-spinor bundle as the basic 'building block'. This allows a clear, direct view of geometric constructions aimed at a theory of such fields on a curved spacetime. In particular, one recovers the Bargmann-Wigner equations and the -dimensional representation of the angular-momentum algebra needed for the Joos-Weinberg equations. Looking for a first-order Lagrangian field theory we argue, through considerations related to the 2-spinor description of the Dirac map, that the needed bundle must be a fibered direct sum of a symmetric 'main sector' - carrying an irreducible representation of the angular-momentum algebra - and an induced sequence of 'ghost sectors'. Then one indeed gets a Lagrangian field theory that, at least formally, can be expressed in a way similar to the Dirac theory. In flat spacetime, one gets plane-wave solutions that are characterized by their values in the main sector. Besides symmetric spinors, the above procedures can be adapted to anti-symmetric spinors and to Hermitian spinors (the latter describing integer-spin fields). Through natural decompositions, the case of a spin-2 field describing a possible deformation of the spacetime metric can be treated in terms of the previous results. [ABSTRACT FROM AUTHOR]

In the R-Minkowski space-time, which we recently defined from an appropriate deformed Poisson brackets that reproduce the Fock coordinate transformation, we derive an extended form for Maxwell's equations by using a generalized version of Feynman's approach. Also, we establish in this context the Lorentz force. As in deformed special relativity, modifying the angular momentum in such a way as to restore the R-Lorentz algebra generates the magnetic Dirac monopole. [ABSTRACT FROM AUTHOR]

We present an Einstein space axially symmetry spacetime admitting closed timelike curves (CTCs) which appear after a certain instant of time, i.e. , a time machine spacetime. The spacetime is a four-dimensional generalization of flat Misner space in curved spacetime, free-from curvature divergences and belongs to type N in the Petrov classification. The spacetime admits a non-expanding, non-twisting, and shear-free null geodesic congruence. [ABSTRACT FROM AUTHOR]

We consider d-dimensional solutions to the electrovacuum Einstein-Maxwell equations with the Weyl tensor of type N and a null Maxwell $$(p+1)$$ -form field. We prove that such spacetimes are necessarily aligned, i.e. the Weyl tensor of the corresponding spacetime and the electromagnetic field share the same aligned null direction (AND). Moreover, this AND is geodetic, shear-free, non-expanding and non-twisting and hence Einstein-Maxwell equations imply that Weyl type N spacetimes with a null Maxwell $$(p+1)$$ -form field belong to the Kundt class. Moreover, these Kundt spacetimes are necessarily $${ CSI}$$ and the $$(p+1)$$ -form is $${ VSI}$$ . Finally, a general coordinate form of solutions and a reduction of the field equations are discussed. [ABSTRACT FROM AUTHOR]

A quantum universe is expressed as a finite unitary relativistic quantum computer network. Its addresses are subject to quantum superposition as well as its memory. It has no exact mathematical model. It Its Hilbert space of input processes is also a Clifford algebra with a modular architecture of many ranks. A fundamental fermion is a quantum computer element whose quantum address belongs to the rank below. The least significant figures of its address define its spin and flavor. The most significant figures of it adress define its orbital variables. Gauging arises from the same quantification as space-time. This blurs star images only slightly, but perhaps measurably. General relativity is an approximation that splits nature into an emptiness with a high symmetry that is broken by a filling of lower symmetry. Action principles result from self-organization pf the vacuum. [ABSTRACT FROM AUTHOR]