A clock-transport method of synchronization employing proper time is described that yields in any given inertial system the same result as slow transport, but that imposes no limit on transport proper speed. It is argued that because the method involves only the empirically validated kinematic invariant proper time, on which all observers must agree, there exists an option to synchronize clocks in such a way that thesimultaneity of spatially separated events is agreed upon by all observers, hence is “absolute.” Such (...) agreement refers only to phase equality of members (present at the events judged simultaneous) of comoving clock sets, not to clock rates or clock phase numerical values in different inertial systems. The demonstration employs only the on-worldline assertions of Einstein's kinematics. It thus depends on a limited subset of his ideas and allows a different identification of the spacelike invariant. (shrink)

The Ehrenfest paradox is reviewed in order to categorize classes of “resolution” that are logically at least semiconsistent. Cantoni's candidate is analyzed with reference to such a taxonomy of resolutions.

Radiationless motion of a charge distribution is reviewed, and the necessary condition conjectured by Goedecke is proved. Then it is shown that a nonrotating, uniformly charged, spherical shell (as seen from its own rest frame) which moves in a relativistically invariant fashion does not have any bounded radiationless motions, unlike its nonrelativistic counterpart.

We obtain a general relativistic unification of gravitation and electromagnetism by simply(1) restricting the metric so that it admits an orthonormal tetrad representation in which the spacelike vectors are curl-free, and(2) identifying the timelike vector as the potential for an electromagnetic field whose only sources are singularities. It follows that: (A) The energy density is everywhere nonnegative, (B) the space is flat if and only if the electromagnetic field vanishes, (C) the vector potential (through which all curvature enters) admits no (...) invariant algebraic decomposition, and satisfies the covariant Lorentz condition identically, (D) the theory is free of “prior geometry,” (E) the electromagnetic self-energy of a spherically symmetric point charge equalsMC 2 , (F) particles deviate from geodesic motion according to the Lorentz force law with radiative reaction, and (G) particles with all electromagnetic multipole structures are included. (shrink)

Astronomical observations of redshifts and the cosmic background radiation show that there is a local frame of reference relative to which the solar system has a well-defined velocity. Also, in cosmology the cosmological principle implies the existence of cosmic time and unique local reference frames at all spacetime points. On the other hand, in a fundamental postulate, the theory of special relativity excludes the possibility of the velocity of the Earth from entering into theories of local physics.The theory put forward (...) in this paper resolves this conflict between local physics and cosmology. The theory retains the essential ingredient of the mathematical structure of special relativity, namely covariance under the Lorentz symmetry group, but changes radically the interpretation of the physical significance of the Lorentz transformation. The theory is based on the postulate that in free space the fundamental interactions in physics are propagated with constant velocity with respect to the local rest frame. In Minkowski spacetime the local rest frame of reference defines a unique time axis and consequently a unique three-dimensional spatial hyperplane. One particularly important result of this is that the theory includes the classical notion of simultaneity. From the fundamental postulate it follows that the equations of local physics, when expressed in terms of the rest frame coordinate system, must be covariant under the Lorentz symmetry group. By the identification of the local rest frame with the (unique) cosmological local reference frame the two theories become mutually consistent.The effects of the motion of the Earth on laboratory experiments are discussed. It is pointed out that existing experimental data do not discriminate between the present theory and that of special relativity: a proposal for an experimental test is made. (shrink)

The inaugural title in the new, Open Access series BSPS Open, The Material Theory of Induction will initiate a new tradition in the analysis of inductive inference. The fundamental burden of a theory of inductive inference is to determine which are the good inductive inferences or relations of inductive support and why it is that they are so. The traditional approach is modeled on that taken in accounts of deductive inference. It seeks universally applicable schemas or rules or a single (...) formal device, such as the probability calculus. After millennia of halting efforts, none of these approaches has been unequivocally successful and debates between approaches persist. The Material Theory of Induction identifies the source of these enduring problems in the assumption taken at the outset: that inductive inference can be accommodated by a single formal account with universal applicability. Instead, it argues that that there is no single, universally applicable formal account. Rather, each domain has an inductive logic native to it. Which that is, and its extent, is determined by the facts prevailing in that domain. Paying close attention to how inductive inference is conducted in science and copiously illustrated with real-world examples, The Material Theory of Induction will initiate a new tradition in the analysis of inductive inference. (shrink)

The old quantum theory of black body radiation was manifestly logically inconsistent. It required the energies of electric resonators to be both quantized and continuous. To show that this manifest inconsistency was inessential to the theory's recovery of the Planck distribution law, I extract a subtheory free of this manifest inconsistency but from which Planck's law still follows.

Recent literature on Bohm's alternative to mainstream quantum mechanics may create the misleading impression that, except for perfunctory dismissals, the theory was ignored by the physics community in the years immediately following its proposal. As a matter of fact, Einstein, Pauli, and Heisenberg all published criticisms of Bohm's theory, explaining their reasons for not accepting the theory. These criticisms will be discussed and evaluated in this article.

An apparent paradox is obtained in all previous treatments of the Trouton–Noble experiment; there is a three-dimensional (3D) torque T in an inertial frame S in which a thin parallel-plate capacitor is moving, but there is no 3D torque T′ in S′, the rest frame of the capacitor. Different explanations are offered for the existence of another 3D torque, which is equal in magnitude but of opposite direction giving that the total 3D torque is zero. In this paper, it is (...) considered that 4D geometric quantities and not the usual 3D quantities are well-defined both theoretically and experimentally in the 4D spacetime. In analogy with the decomposition of the electromagnetic field F (bivector) into two 1-vectors E and B we introduce decomposition of the 4D torque N (bivector) into 1-vectors N s , N t . It is shown that in the frame of “fiducial” observers, in which the observers who measure N s and N t are at rest, and in the standard basis, only the spatial components $N_{s}^{i}$ and $N_{t}^{i}$ remain, which can be associated with components of two 3D torques T and T t . In such treatment with 4D geometric quantities the mentioned paradox does not appear. The presented explanation is in complete agreement with the principle of relativity and with the Trouton–Noble experiment without the introduction of any additional torque. (shrink)

We argue that current constructive approaches to the special theory of relativity do not derive the geometrical Minkowski structure from the dynamics but rather assume it. We further argue that in current physics there can be no dynamical derivation of primitive geometrical notions such as length. By this we believe we continue an argument initiated by Einstein.

Einstein’s equivalence principle has a number of problems, and it is often applied incorrectly. Clocks on the earth do not seem to be affected by the sun’s gravitational potential. The most commonly accepted reason given is a faulty application of the equivalence principle. While no valid reason is available within either the special or general theories of relativity, ether theories can provide a valid explanation. A clock bias of the correct magnitude and position dependence can convert the Selleri transformation of (...) ether theories into an apparent Lorentz transformation, which gives rise to an apparent equivalence of inertial frames. The results indicate that the special theory is invalid and that only an apparent relativity exists. (shrink)

The present paper attempts to show that a 1915 article by Erich Kretschmann must be credited not only for being the source of Einstein’s point-coincidence remark, but also for having anticipated the main lines of the logical-empiricist interpretation of general relativity. Whereas Kretschmann was inspired by the work of Mach and Poincaré, Einstein inserted Kretschmann’s point-coincidence parlance into the context of Ricci and Levi-Civita’s absolute differential calculus. Kretschmann himself realized this and turned the point-coincidence argument against Einstein in his second (...) and more famous 1918 paper. While Einstein had taken nothing from Kretschmann but the expression “point-coincidences”, the logical empiricists, however, instinctively dragged along with it the entire apparatus of Kretschmann’s conventionalism. Disappointingly, in their interpretation of general relativity, the logical empiricists unwittingly replicated some epistemological remarks Kretschmann had written before General Relativity even existed. (shrink)

The present note is intended to draw the reader's attention to the analysis of the relation between Newtonian Mechanics and Special Relativity Mechanics (henceforth to be referred to as NM and SRM), given by Philipp Frank, one of the classics of Logical Empiricism (in Frank [1938]). Frank's analysis of the relation between NM and SRM is interesting in many ways. Firstly, it shows clearly that problems of disruptive changes and of conceptual disparity were known to and discussed by Logical Empiricists (...) and that, therefore, some of them at least were not at all blinded to 'dynamic' problems of changes in actual science by their view of physical theories as interpreted axiomatic systems and did not deal with those theories as 'static, frozen in logical mold'. Secondly, it reveals some of the reasons for the Logical Empiricist rejection of what came to be known later as the incommensurability claim. (shrink)

I have so far ignored Earman's Section IV in which spatiotemporal coincidence is discussed. The answer will be clear from the preceding: the exact definitions and principles of the exact theories we have displayed are to be discussed with reference to the special and not the general theory of relativity. But moreover, Earman's transition from (C) to (1) assumes what we do not grant: that events are causally connectible exactly if the points in the mathematical space-time at which they are (...) located are linked by a causal curve.This captures in a nutshell my own conclusions. The first is that the causal theory, after its success vis-à-vis the STR, must now provide a detailed analysis of spatiotemporal concepts in the GTR. The second is that the points raised by Earman do not provide substantive reasons for doubting the adequacy of the causal theory to this task, because Earman insists in his extrapolations on a much closer relation between the empirical structure of events and the mathematical structures that model it than ought to be assumed. (shrink)

Recent ?dynamical? approaches to relativity by Harvey Brown and his colleagues have used John Bell's own solution to a problem in relativity which has in the past sometimes been called ?Bell's spaceships paradox?, in a central way. This paper examines solutions to this problem in greater detail and from a broader philosophical perspective than Brown et al. offer. It also analyses the well-known analogy between special relativity and classical thermodynamics. This analysis leads to the sceptical conclusion that Bell's solution yields (...) neither new philosophical insights concerning the foundations of relativity nor differential support for a specific view concerning the existence of space-time. (shrink)

A recent paper suggested that if Galilean covariance was extended to signals and interactions, the resulting theory would contain such anomalies as would have impelled physicists towards special relativity even without empirical prompts. I analyze this claim. Some so-called anomalies turn out to be errors. Others have classical analogs, which suggests that classical physicists would not have viewed them as anomalous. Still others, finally, remain intact in special relativity, so that they serve as no impetus towards this theory. I conclude (...) that Galilean covariance is insufficient to derive special relativity. (shrink)

The equation for the fundamental field quantity ϱ is obtained. It is Div $\rho ^\mu (\Omega _1 ) = \operatorname{h} \int {[\rho _\mu (\Omega _1 ),\rho ^\mu (\Omega _2 )]_ - \operatorname{d} \Omega _2 } $ ,where h is an arbitrary function oft andr, and [,]− is the commutator. The derivation requires the following hypotheses:(1) All of physical reality is completely described by the field ϱ.(2) Relativistic covariance of the equations governing ϱ.(3) Principle of continguous action.(4) Conservation of total amount (...) of ϱ. The equation appears to be unique. It is suggested that the physical world corresponds to ϱ being a2×2 matrix. A close correspondence between the basic equation and Maxwell's equation is displayed. The electromagnetic vector potential Aμ is identified with ε ρμ dΩ. Conservation laws on various measures of ϱ are obtained. The symmetry groups of the basic equation are derived. A preliminary attempt to connect the field ϱ to the metric is made via Einstein's gravitational equation Gμυ =KTμυ. (shrink)

Retention of structure across theory change has been invoked in support of a ‘structural’ alternative to more traditional entity-based scientific realism. In that context the transition from Newtonian mechanics to the Special Theory of Relativity is often regarded as a very significant instance of structural preservation, or retention, associated with correspondence-based recovery. The joint derivation, from a small set of elementary and ontologically neutral assumptions, of both the Galilei and the Lorentz transformation exemplifies the virtues of structural approaches to the (...) foundations of physical theories. The common origination of the resulting two relativistic frameworks sheds light on both the successes and the limitations of correspondence claims. However, the cognitive-operational character of the basic assumptions lends no support to the structural realist’s ‘inference to the best explanation’. (shrink)

The Mössbauer rotor effect recently gained a renewed interest due to the discovery and explanation of an additional effect of clock synchronization which has been missed for about 50 years, i.e. starting from a famous book of Pauli, till some recent experimental analyses. The theoretical explanation of such an additional effect is due to some recent papers in both the general relativistic and the special relativistic frameworks. In the first case the key point of the approach is the Einstein’s equivalence (...) principle, which, in the words of the same Einstein, enables “the point of view to interpret the rotating system K’ as at rest, and the centrifugal field as a gravitational field”. In this paper, we analyse both the history of the Mössbauer rotor effect and its interpretation from the point of view of Einstein’s general theory of relativity by adding some new insight. In particular, it will be shown that, if on one hand the “traditional” effect of redshift has a strong analogy with the gravitational redshift, on the other hand the additional effect of clock synchronization has an intriguing analogy with the cosmological redshift. Finally, we show that a recent claim in the literature that the second effect of clock synchronization does not exist is not correct. (shrink)

We find the equation of state p, ρ ∫ T 6,which gives the value of the sound velocity c 27 = 0.20,in agreement with the “realistic” equation of state for hot hadronic matter suggested by Shuryak, in the framework of a covariant relativistic statistical mechanics of an event-anti-event system with small chemical and mass potentials. The relativistic mass distribution for such a system is obtained and shown to be a good candidate for fitting hadronic resonances, in agreement with the phenomenological (...) models of Hagedorn, Shuryak, et al. This distribution provides a correction to the value of specific heat 3/2,of the order of 5.5%,at low temperatures. (shrink)

The physicist's conception of space-time underwent two major upheavals thanks to the general theory of relativity and quantum mechanics. Both theories play a fundamental role in describing the same natural world, although at different scales. However, the inconsistency between them emerged clearly as the limitation of twentieth-century physics, so a more complete description of nature must encompass general relativity and quantum mechanics as well. The problem is a theorists' problem par excellence. Experiment provide little guide, and the inconsistency mentioned above (...) is an important problem which clearly illustrates the intermingling of philosophical, mathematical, and physical thought. In fact, in order to unify general relativity with quantum field theory, it seems necessary to invent a new mathematical framework which will generalise Riemannian geometry and therefore our present conception of space and space-time. Contemporary developments in theoretical physics suggest that another revolution may be in progress, through which a new kind of geometry may enter physics, and space-time itself can be reinterpreted as an approximate, derived concept. The main purpose of this article is to show the great significance of space-time geometry in predetermining the laws which are supposed to govern the behaviour of matter, and further to support the thesis that matter itself can be built from geometry, in the sense that particles of matter as well as the other forces of nature emerges in the same way that gravity emerges from geometry. Scientific research is not a process of steady accumulation of absolute truths, which has culminated in present theories, but rather a much more dynamic kind of process in which there are no final theoretical concepts valid in unlimited domains. (David Bohm). (shrink)

The Lagrangian and Hamiltonian properties of classical electrodynamics models and their associated Dirac quantizations are studied. Using the vacuum field theory approach developed in (Prykarpatsky et al. Theor. Math. Phys. 160(2): 1079–1095, 2009 and The field structure of a vacuum, Maxwell equations and relativity theory aspects. Preprint ICTP) consistent canonical Hamiltonian reformulations of some alternative classical electrodynamics models are devised, and these formulations include the Lorentz condition in a natural way. The Dirac quantization procedure corresponding to the Hamiltonian formulations is (...) developed. The crucial importance of the rest reference systems, with respect to which the dynamics of charged point particles is framed, is explained and emphasized. A concise expression for the Lorentz force is derived by suitably taking into account the duality of electromagnetic field and charged particle interactions. Finally, a physical explanation of the vacuum field medium and its relativistic properties fitting the mathematical framework developed is formulated and discussed. (shrink)

It is shown that (a) both the dispersion relations between the mean frequency θ0 and the mean wave number k 0 are invariant under the Lorentz transformation; and (b) the relativistic Doppler effects on θ 0 and k 0 differ. In the suboptic packet there is anomalous red shift in the mean wave number k' 0 received from a source receding with speed v: k′ 0 changes sign through zero as v goes through the value vg, the mean group velocity (...) in the packet. In the superoptic packet the anomalous red shift is in the mean frequency θ′ 0 which reverses sign through zero as v goes through the value vp, the mean phase velocity in the packet. This last finding indicates a blackout of the superoptic signal when propagated toward a receiver moving away from the source at a speed greater than vp. There is no violation of causality involved, and the final conclusion of the paper is that it is not a fundamental axiom of “special relativity,” as usually believed, to deny that information can be transmitted at speeds greater than c. (shrink)

In relativistic mechanics the energy-momentum of a free point mass moving without acceleration forms a four-vector. Einstein’s celebrated energy-mass relation E=mc 2 is commonly derived from that fact. By contrast, in Newtonian mechanics the mass is introduced for an accelerated motion as a measure of inertia. In this paper we rigorously derive the relativistic point mechanics and Einstein’s energy-mass relation using our recently introduced neoclassical field theory where a charge is not a point but a distribution. We show that both (...) the approaches to the definition of mass are complementary within the framework of our field theory. This theory also predicts a small difference between the electron rest mass relevant to the Penning trap experiments and its mass relevant to spectroscopic measurements. (shrink)

We investigate the possibility of inducing the cosmological constant from extra dimensions by embedding our four-dimensional Riemannian space-time into a five-dimensional Weyl integrable space. Following the approach of the space-time-matter theory we show that when we go down from five to four dimensions, the Weyl field may contribute both to the induced energy-tensor as well as to the cosmological constant Λ, or more generally, it may generate a time-dependent cosmological parameter Λ(t). As an application, we construct a simple cosmological model (...) in which Λ(t) has some interesting properties. (shrink)

The idea that a serious threat to scientific realism comes from unconceived alternatives has been proposed by van Fraassen, Sklar, Stanford and Wray among others. Peter Lipton's critique of this threat from underconsideration is examined briefly in terms of its logic and its applicability to the case of space-time and particle physics. The example of space-time and particle physics indicates a generic heuristic for quantitative sciences for constructing potentially serious cases of underdetermination, involving one-parameter family of rivals T_m that work (...) as a team rather than as a single rival against default theory T_0. In important examples this new parameter has a physical meaning and makes a crucial _conceptual_ difference, shrinking the symmetry group and in some case putting gauge freedom, formal indeterminism vs. determinism, the presence of the hole argument, etc., at risk. Methodologies akin to eliminative induction or tempered subjective Bayesianism are more demonstrably reliable than the custom of attending only to "our best theory": they can lead either to a serious rivalry or to improved arguments for the favorite theory. The example of General Relativity vs. massive spin 2 gravity, a recent topic in the physics literature, is discussed. Arguably the General Relativity and philosophy literatures have ignored the most serious rival to General Relativity. (shrink)

Einstein’s “point-coincidence argument'” as a response to the “hole argument” is usually considered as an expression of “Leibniz equivalence,” a restatement of indiscernibility in the sense of Leibniz. Through a historical-critical analysis of Logical Empiricists' interpretation of General Relativity, the paper attempts to show that this labeling is misleading. Logical Empiricists tried explicitly to understand the point-coincidence argument as an indiscernibility argument of the Leibnizian kind, such as those formulated in the 19th century debate about geometry, by authors such as (...) Poincaré, Helmholtz or Hausdorff. However, they clearly failed to give a plausible account of General Relativity. Thus the point-coincidence/hole argument cannot be interpreted as Leibnizian indiscernibility argument, but must be considered as an indiscernibility argument of a new kind. Weyl's analysis of Leibniz's and Einstein's indiscernibility arguments is used to support this claim. (shrink)

There is an important point behind Earman's criticisms of the causal theory of time and space-time. This point has been made perspicuously in a recent paper by Glymour. It concerns the novel problems raised for a theory of space-time by the general theory of relativity, and I shall explain it briefly in Section II below. Section I briefly states my own view of the status of the causal theory, and Sections III and IV deal with Earman's specific criticisms.

In this paper the quantum covariant relativistic dynamics of many bodies is reconsidered. It is emphasized that this is an event dynamics. The events are quantum statistically correlated by the global parameter τ. The derivation of an event Boltzmann equation emphasizes this. It is shown that this Boltzmann equation may be viewed as exact in a dilute event limit ignoring three event correlations. A quantum entropy principle is obtained for the marginal Wigner distribution function. By means of event linking (concatenations) (...) particle properties such as the equation of state may be obtained. We further reconsider the generalized quantum equilibrium ensemble theory and the free event case of the Fermi-Dirac and Bose-Einstein distributions, and some consequences. The ultra-relativistic limit differs from the non-covariant theory and is a test of this point of view. (shrink)

It is shown by means of general principles and specific examples that, contrary to a long-standing misconception, the modern mathematical physics of compressible fluid dynamics provides a generally consistent and efficient language for describing many seemingly fundamental physical phenomena. It is shown to be appropriate for describing electric and gravitational force fields, the quantized structure of charged elementary particles, the speed of light propagation, relativistic phenomena, the inertia of matter, the expansion of the universe, and the physical nature of time. (...) New avenues and opportunities for fundamental theoretical research are thereby illuminated. (shrink)

Gyrogroup theory and its applications is introduced and explored, exposing the fascinating interplay between Thomas precession of special relativity theory and hyperbolic geometry. The abstract Thomas precession, called Thomas gyration, gives rise to grouplike objects called gyrogroups [A, A. Ungar, Am. J. Phys.59, 824 (1991)] the underlying axions of which are presented. The prefix gyro extensively used in terms like gyrogroups, gyroassociative and gyrocommutative laws, gyroautomorphisms, and gyrosemidirect products, stems from their underlying abstract Thomas gyration. Thomas gyration is tailor made (...) for hyperbolic geometry. In a similar way that commutative groups underlie vector spaces, gyrocommutative gyrogroups underlie gyrovector spaces. Gyrovector spaces, in turn, provide a most natural setting for hyperbolic geometry in full analogy with vector spaces that provide the setting for Euclidean geometry. As such, their applicability to relativistic physics and its spacetime geometry is obvious. (shrink)

In the established space-time coordinate-transformation (STCT) interpretation of special relativity theory, relativistic changes are consequent upon the Lorentz transformation of coordinate clocks and rods between relatively moving systems. In the proposed alternative interpretation, relativistic changes occur only in association with physical interactions, and are direct alterations in the variables of the observed system. Since space-time and momentum-energy are conjugate four-vectors, transformation of a space or time variable of a system is to be expected only if there is a concomitant transformation (...) of the corresponding momentum or energy variable. The Lorentz invariance of the scalar entropy functionS supports the interaction interpretation; timet=f(S) of a macroscopic, entropy clock should give a Lorentz-invariant time measure, and an illustrative entropy clock is discussed. Noninteracting physical processes may be called Clausius processes, in contrast to Lorentz processes for which there is interaction and associated Lorentz transformation. Changes of energy and frequency, withE=hv, are instances of the parallel relativistic transformations. Likewise, the variation with velocity in decay time of mesons follows directly from the relativistic energy transformation of decay products; this relationship is shown for muons by a simple calculation with β-decay theory. (shrink)

Is it possible to construct an alternative framework for the description of physical reality that is not based on space and time? According to Kant, because of the incorrigibility of the spatiotemporal scheme, the contents of any such alternative will be beyond our cognitive grasp. Nonetheless, the possibility of constructing such a descriptive scheme poses itself as an intriguing challenge. In this paper, we attempt to answer this challenge by exploiting an analytical tool extensively used by physicists and engineers: the (...) utilisation of multiple representations of the same data using integral transforms – for example, the Fourier transform. According to the spectral picture we propose, frequencies and wavelengths, related to time and space by the Fourier transform, form an adequate alternative basis for describing physical systems, and one that is of equal richness to the spatiotemporal picture. Furthermore, the routine use of Fourier analysis applied to familiar physical systems suggests ways in which sense organs might be constructed such that they naturally give rise to a spectral representation of the world. Although we might never be able to imagine perceiving the world in this way, we can nonetheless describe the contents of such a mode of perception and relate them precisely to our own world-view. Hence, we suggest in a Kantian spirit, that the spatiotemporal description of the world is not unique. (shrink)

The fundamental open questions of general relativity theory are the unification of the gravitational field with other fields, aiming at a unified geometrization of physics, as well as the renormalization of relativistic gravitational theory in order to obtain their self-consistent solutions. These solutions are to furnish field-theoretic particle models—a problem first discussed by Einstein. In addition, we are confronted with the issue of a coupling between gravitational and matter fields determined (not only) by Einstein's principle of equivalence, and also with (...) the question of the geometric meaning of a gravitational quantum theory. In our view, all these problems are so closely related that they warrant a general solution. We treat mainly the concepts suggested by Einstein and Weyl. (shrink)

PhD dissertation addressing what can be called conceptual-mathematical anomalies in quantum electrodynamics. This work can be seen as following the line of philosophy of physics studies of quantum field theory that started to emerge in a systematic way in the early eighties of last century. One example is Teller’s work on standard quantum electrodynamics.In this work, by following a historical approach, I will return to the standard version of quantum electrodynamics, which is the only one available when we want to (...) get numbers out to compare with experimental results. This work spins around two main vectors. One is the divergence of the S-matrix series expansion, the other is the spatio-temporal description of physical processes in the theory. (shrink)

We discuss the concepts of Weyl and Riemann frames in the context of metric theories of gravity and state the fact that they are completely equivalent as far as geodesic motion is concerned. We apply this result to conformally flat spacetimes and show that a new picture arises when a Riemannian spacetime is taken by means of geometrical gauge transformations into a Minkowskian flat spacetime. We find out that in the Weyl frame gravity is described by a scalar field. We (...) give some examples of how conformally flat spacetime configurations look when viewed from the standpoint of a Weyl frame. We show that in the non-relativistic and weak field regime the Weyl scalar field may be identified with the Newtonian gravitational potential. We suggest an equation for the scalar field by varying the Einstein-Hilbert action restricted to the class of conformally-flat spacetimes. We revisit Einstein and Fokker’s interpretation of Nordström scalar gravity theory and draw an analogy between this approach and the Weyl gauge formalism. We briefly take a look at two-dimensional gravity as viewed in the Weyl frame and address the question of quantizing a conformally flat spacetime by going to the Weyl frame. (shrink)

The generally covariant Lagrangian densityG = ℛ + 2K ℒmatter of the Hamiltonian principle in general relativity, formulated by Einstein and Hilbert, can be interpreted as a functional of the potentialsg ikand φ of the gravitational and matter fields. In this general relativistic interpretation, the Riemann-Christoffel form Γ kl i = kl i for the coefficients г kl i of the affine connections is postulated a priori. Alternatively, we can interpret the LagrangianG as a functional of φ, gik, and the (...) coefficients г kl i . Then the г kl i are determined by the Palatini equations. From these equations and from the symmetry г kl i = г lk i for all matter fields with δℒ/δΓ=0 the Christoffel symbols again result. However, for Dirac's bispinor fields, δℒ/δΓ becomes dependent on the Dirac current, essentially with a coupling factor ∼Khc. In this case, the Palatini equations define a new transport rule for the spinor fields, according to which a second universal interaction results for the Dirac spinors, besides Einstein's gravitation. The generally covariant Dirac wave equations become the general relativistic nonlinear Heisenberg wave equations, and the second universal interaction is given by a Fermi-like interaction term of the V-A type. The geometrically induced Fermi constant is, however, very small and of the order 10−81erg cm3. (shrink)

The concept of relativistic length is introduced and discussed. The definition is based on a measuring procedure that directly uses a clock and light signals (analogous to the radar method), and it has as a consequence the increase of the longitudinal dimensions of fast-moving objects. Furthermore, the concept of relativistic length introduced here is in logical accord with the notion of distance utilized in relativistic electrodynamics.

Gyrogroup theory [A. A. Ungar, Found. Phys. 27, 881–951 (1997)] enables the study of the algebra of Einstein's addition to be guided by analogies shared with the algebra of vector addition. The capability of gyrogroup theory to capture analogies is demonstrated in this article by exposing the relativistic composite-velocity reciprocity principle. The breakdown of commutativity in the Einstein velocity addition ⊕ of relativistically admissible velocities seemingly gives rise to a corresponding breakdown of the relativistic composite-velocity reciprocity principle, since seemingly (i) (...) on one hand, the velocity reciprocal to the composite velocity u⊕v is −(u⊕v) and (ii) on the other hand, it is (−v)⊕(−u). But (iii) −(u⊕v)≠(−v)⊕(−u). We remove the confusion in (i), (ii), and (iii) by employing the gyrocommutative gyrogroup structure of Einstein's addition and, subsequently, present the relativistic composite-velocity reciprocity principle with the Thomas rotation that it involves. (shrink)