If is often taken for granted that on a rotating disk it is possible to operate a global 3+1 splitting of spacetime such that both lengths and time intervals are uniquely defined in terms of measurements performed by real rods and real clocks at rest on the platform. This paper shows that this assumption, although widespread and apparently trivial, leads to an anisotropy of the velocity of two light beams traveling in opposite directions along the rim of the disk, (...) which in turn implies some recently pointed out paradoxical consequences undermining the self-consistency of the special theory of relativity (SRT). A correct application of the SRT solves the problem and recovers complete internal consistency for the theory. As an immediate consequence, it is shown that the Sagnac effect only depends on the nonhomogeneity of time of the platform and has nothing to do with any anisotropy of the speed of light along the rim of the disk, contrary to an incorrect but widely held idea. (shrink)

The Robertson–Walker (RW) metric allows us to apply general relativity to model the behavior of the Universe as a whole (i.e., cosmology). We can properly interpret various cosmological observations, like the cosmological redshift, the Hubble parameter, geometrical distances, and so on, if we identify fundamental observers with individual galaxies. That is to say that the interpretation of observations of modern cosmology relies on the RW metric. The RW model satisfies the cosmological principle in which the 3-space always remains isotropic and (...) homogeneous. One can derive the cosmological redshift relation from this condition. We show that it is still possible for us to obtain consistent results in a specific time-varying speed-of-light model without spoiling the success of the standard model. The validity of this model needs to be determined by observations. (shrink)

While it has often been proposed that, fundamentally, Lorentz-invariance is not respected in a quantum theory of gravity, it has been difficult to reconcile deviations from Lorentz-invariance with quantum field theory. The most commonly used mechanisms either break Lorentz-invariance explicitly or deform it at high energies. However, the former option is very tightly constrained by experiment already, the latter generically leads to problems with locality. We show here that there exists a third way to integrate deviations from Lorentz-invariance into quantum (...) field theory that circumvents the problems of the other approaches. The way this is achieved is an extension of the standard model in which photons can have different speeds without singling out a preferred restframe, but only as long as they are in a quantum superposition. Once a measurement has been made, observables are subject to the laws of special relativity, and the process of measurement introduces a preferred frame. The speed of light can take on different values, both superluminal and subluminal (with respect to the usual value of the speed of light), without the need for Lorentz-invariance violating operators and without tachyons. We briefly discuss the relation to deformations of special relativity and phenomenological consequences. (shrink)

This paper gives two complete and elementary proofs that if the speed of light over closed paths has a universal value c, then it is possible to synchronize clocks in such a way that the one-way speed of light is c. The first proof is an elementary version of a recent proof. The second provides high precision experimental evidence that it is possible to synchronize clocks in such a way that the one-way speed of (...) class='Hi'>light has a universal value. We also discuss an old incomplete proof by Weyl which is important from an historical perspective. (shrink)

This article traces the significant links that Virilio's dromological analysis posits between the social and political impact of mechanical vehicles and communications media. Focusing on the way that the 'revolutions' of transportation and transmission have fundamentally altered contemporary experiences of space and time, the article explores the implications of Virilio s concept of spatio-temporal 'overexposure". My contention is that Virilio's work has been of critical importance in placing questions about differential spatio-temporal regimes Oin the political agenda. However, his critique of (...) 'tele-presence. is ultimately hampered by his continued attachment to a phenomenological subject, which I argue does not provide an adequate basis from which to rethink the dominant social relations of time and space manifest in the contemporary media. (shrink)

One of Ole Römer's most influential contributions to astronomy was the theory that light has a finite speed, which he calculated from inequalities in the motion of a satellite of Jupiter. The English astronomer John Flamsteed, first director of the Royal Observatory at Greenwich, is credited with being an early and influential supporter of the theory. This article examines how he came to be so, taking issue with the claim that he was instantly converted to the idea by (...) a personal encounter with Römer. The publication of Flamsteed's Correspondence has made illuminating material newly accessible; through letters it is possible to track the gradual development of his thinking and how it related to his dealings with Römer and with Giovanni Domenico Cassini (director of the Paris Observatory). The resulting account offers new insights into their attempts to share information, in a situation where motives for collaborating were counterbalanced by a potential for rivalry and conflict, and into the interlinked roles played by written correspondence, personal meetings and empirical investigation in the spreading of new ideas. (shrink)

There are two types of fluctuations in the quantum vacuum: type 1 vacuum fluctuations are on shell and can interact with matter in specific, limited ways that have observable consequences; type 2 vacuum fluctuations are off shell and cannot interact with matter. A photon will polarize a type 1, bound, charged lepton–antilepton vacuum fluctuation in much the same manner that it would polarize a dielectric, suggesting the method used here for calculating the permittivity $$\epsilon _{0}$$ϵ0 of the vacuum. In a (...) model that retains only leading terms, $$\epsilon _{0} \cong ^{2}= 9.10\times 10^{-12}$$ϵ0≅2=9.10×10-12 C/. The calculated value for $$\epsilon _{0}$$ϵ0 is 2.7% more than the accepted value. The permittivity of the vacuum, in turn, determines the speed c of light in the vacuum. Since the vacuum is at rest with respect to every inertial frame of reference, c is the same in every inertial reference frame. (shrink)

It has been argued that the existence of a minimum observable interval of space and time is a model-independent result of the combination of quantum field theory and general relativity. In this paper, I promote this result to a fundamental postulate, called the MOIST postulate. It is argued that the postulate leads to the existence of a maximum signal speed and its invariance. This new result may have two interesting implications. On the one hand, it suggests that the MOIST (...) postulate can explain the invariance of the speed of light, and thus it might provide a deeper logical foundation for special relativity. Moreover, it suggests that the speed constant c in modern physics is not the actual speed of light in vacuum, but the ratio of the minimum observable length to the minimum observable time interval. On the other hand, the result also suggests that the existing experiments confirming the invariance of the speed of light already provide observational evidence to support the MOIST postulate. (shrink)

In connection with another article by the author, we show how it might be possible to travel faster than the speed of light. We show that for clocks and rods moving faster than the speed of light, we get instead of “time dilation” and “Lorentz contraction,” respectively, “time contraction” and “Lorentz expansion,” respectively. It is shown that this paper is in confirmation with earlier articles dealing with this subject.

Recent years have seen the attention of physicists and philosophers, both at home and abroad, increasingly drawn, as is evident in the professional literature, to the question of the possibility of the existence of particles moving at speeds greater than that of light and to determining the physical and philosophical consequences of this hypothesis. The philosophical consequences have to do primarily with the causality principle. We are in receipt of two articles in which these questions are examined from different (...) perspectives and which supplement each other. (shrink)

The most recent attempt at factually establishing a "true" value for the one-way velocity of light is shown to be faulty. The proposal consists of two round-trip photons travelling first in vacuo and then through a medium of refractive index n before returning to their common point of origin. It is shown that this proposal, as well as a similar one considered by Salmon (1977), presupposes that the one-way velocities of light are equal to the round-trip value. Furthermore, (...) experiments of this type, involving regions of space with varying refractive indices, cannot "single out" any factual value for the Reichenbach-Grünbaum ε factor thus posing no threat to the conventionalist thesis. (shrink)

Fundamental incompatibility arises at the interface of quantum mechanics and the special theory of relativity with Einstein synchronization, in which simultaneity is not absolute. It has, however, been shown that a relativistic theory preserving absolute simultaneity allows to formulate Lorentz-covariant quantum theory, at a price of introducing a preferred frame of reference manifesting itself in a directional anisotropy of the speed of light. We show that a supposed method of distinguishing between these two theories based on the Doppler (...) effect is insensitive to this anisotropy. Both theories are indistinguishable if only kinematic effects for light or subluminal signals are considered. (shrink)

In recent years there has been rather extensive discussion in the physics literature of the possibility of transmission of material effects at speeds exceeding that of light.

We describe our explicit Lorentz-invariant solution of the Einstein and null geodesic equations for the deflection experiment of 2002 September 8 when a massive moving body, Jupiter, passed within 3.7’ of a line-of-sight to a distant quasar. We develop a general relativistic framework which shows that our measurement of the retarded position of a moving light-ray deflecting body (Jupiter) by making use of the gravitational time delay of quasar’s radio wave is equivalent to comparison of the relativistic laws of (...) the Lorentz transformation for gravity and light. Because, according to Einstein, the Lorentz transformation of gravity field variables must depend on a fundamental speed c, its measurement through the retarded position of Jupiter in the gravitational time delay allows us to study the causal nature of gravity and to set an upper limit on the speed of propagation of gravity in the near zone of the solar system as contrasted to the speed of the radio waves. In particular, the v/c term beyond of the standard Einstein’s deflection, which we measured to 20% accuracy, is associated with the aberration of the null direction of the gravity force (“aberration of gravity”) caused by the Lorentz transformation of the Christoffel symbols from the static frame of Jupiter to the moving frame of observer. General relativistic formulation of the experiment identifies the aberration of gravity with the retardation of gravity because the speed of gravitational waves in Einstein’s theory is equal to the speed of propagation of the gravity force. We discuss the misconceptions which have inhibited the acceptance of this interpretation of the experiment. We also comment on other interpretations of this experiment by Asada, Will, Samuel, Pascual–Sánchez, and Carlip and show that their “speed of light” interpretations confuse the Lorentz transformation for gravity with that for light, and the fundamental speed of gravity with the physical speed of light from the quasar. For this reason, the “speed of light” interpretations are not entirely consistent with a retarded Liénard–Wiechert solution of the Einstein equations, and do not properly incorporate how the phase of the radio waves from the quasar is perturbed by the retarded gravitational field of Jupiter. Although all of the formulations predict the same deflection to the order of v/c, our formulation shows that the underlying cause of this deflection term is associated with the aberration of gravity and not of light, and that the interpretations predict different deflections at higher orders of v/c beyond the Shapiro delay, thus, making their measurement highly desirable for deeper testing of general relativity in future astrometric experiments like Gaia, SIM, and SKA. (shrink)

Following aluminum as part of a material culture of speed and lightness, this article examines how assemblages of energy and metals connect built environments, ways of life, and ideologies of acceleration. Aluminum can be theorized as a circulatory matrix that forms an energy culture. Through a discussion of speed and social justice, the history of aluminium-based socioecologies reveals how the materiality of energy forms assemblages of objects, infrastructures, and practices. The article then traces the aluminum industry’s involvement in (...) the production and distribution of energy itself both at the national scale of power grids and in the emergence of transnational transfers of energy, such as hydropowered smelters in Iceland. Finally, this analysis of deeply embedded energy cultures calls for a transnational approach to the accelerated socioecologies of aluminum production and consumption; and for energy transition theories to pay closer attention to the figured worlds and figuring work of the military-industrial complex. (shrink)

The convention that the one-way velocity of light is isotropic is shown to be independent of the postulates of relativity in a globally Minkowskian continuum, but not in a continuum which is only locally Minkowskian.

The purpose of the present paper is to develop kinematics of the special relativity with an anisotropy of the one-way speed of light. As distinct from a common approach, when the issue of anisotropy of the light propagation is placed into the context of conventionality of distant simultaneity, it is supposed that an anisotropy of the one-way speed of light is due to a real space anisotropy. In that situation, some assumptions used in developing the (...) standard special relativity kinematics are not valid so that the “anisotropic special relativity” kinematics should be developed based on the first principles, without refereeing to the relations of the standard relativity theory. In particular, using condition of invariance of the interval between two events becomes unfounded in the presence of anisotropy of space since the standard proofs drawing the interval invariance from the invariance of equation of light propagation are not valid in that situation. Instead, the invariance of the equation of light propagation, which is a physical law, should be taken as a first principle. A number of other physical requirements, associativity, reciprocity and so on are satisfied by the requirement that the transformations between the frames form a group. Finally, the correspondence principle is to be satisfied which implies that the coordinate transformations should turn into the Galilean transformations in the limit of small velocities. The above formulation based on the invariance and group property suggests applying the Lie group theory apparatus which includes the following steps: constructing determining equations for the infinitesimal group generators using the invariance condition; solving the determining equations; specifying the solutions using the correspondence principle; defining the finite transformations by solving the Lie equations; relating the group parameter to physical parameters. The transformations derived in such a way, as distinct from the transformations derived in the context of conventionality of distant simultaneity, cannot be converted into the standard Lorentz transformations by a coordinate change. The anisotropic nature of the presented transformations manifests itself in that they do not leave the interval invariant but only provide the conformal invariance of the interval. The relations that represent measurable effects include the conformal factor which depends on the relative velocity of the frames and the anisotropy degree. It is important to note the use of the correspondence principle as a heuristic principle which allows to relate the conformal factor to the anisotropy degree and thus completely specify the transformations and observable quantities. (shrink)

We point out that the acceptance of the relativity principle together with the homogeneity and isotropy of space and the homogeneity of time inevitably leads to the Lorentz spacetime transformation with a universal limiting speed σ. Speculations on possible new four-dimensional symmetries involving a variable “speed of light” such as that proposed by Hsu must therefore be dismissed on such a basis alone. In this paper we draw attention to some logical inconsistencies in Hsu's attempt at establishing (...) a new space-light transformation law, and follow with a discussion on why such an attempt must necessarily fail. (shrink)

Special relativity insists that the speed of light in a vacuum is constant for all inertial observers. This is often said to be counterintuitive: why should light alone, among all things in the world, return the same speed value to all inertial observers, regardless of their different states of motion? I argue that this question or puzzle arises because physics misconstrues light by characterizing it as a freestanding phenomenon. As James Gibson insisted, and as any (...) analysis of the visual experience makes plain, light, the agency of sight, cannot be overtaken by sight. A better characterization of light is Gibson's optic array, which prompts the realization that our prior complicity with light keeps us from getting leverage on it as a freestanding phenomenon, and this is why it returns the same speed value to all observers. To show the limitation of freestanding light, I offer two derivations of relativistic time dilation. The first imagines freestanding light and then, to complete the derivation, artificially requires light speed constancy; the second achieves the same result in a fully natural way?that is, without putting observers in an abstract, arguably impossible, situation?by merely attending to the seeing experience. (shrink)

This article addresses recent science fiction films about the colonization of outer worlds, or space-steading, in the context of the longer colonial history of the frontier. Paying particular attention to Interstellar (Christopher Nolan, 2014), Serenity (Joss Whedon, 2005) and The Wild Blue Yonder (Werner Herzog, 2005), I argue that colonizing outer space is not only a race to the new frontier, but that this takes place because technologies that picture space have quickened the pulse. Through its imagining of the end (...) of times as a reiteration of colonizing adventure, and the emptying of people from their place, the technology of film has itself produced the accident (Virilio, 2007) of an uninhabited earth. As suggested by the cinematically derived kinesis of wormholes, space wrinkles, and warp speeds, what might be left as a form of life is none other than film itself. The hyper-kinesis of film spectacle takes on a non-human life of its own, which, in science fiction film, constitutes a form of self-alienation, removing viewers from the places they actually inhabit and displacing the histories they unfold. In this way, I address what is truly cinematic about the film frontier traversed by the new space of uber-masculine adventurer-settlers. (shrink)

This paper gives two complete and elementary proofs that if the speed of light over closed paths has a universal value c, then it is possible to synchronize clocks in such a way that the one-way speed of light is c. The first proof is an elementary version of a recent proof. The second provides high precision experimental evidence that it is possible to synchronize clocks in such a way that the one-way speed of (...) class='Hi'>light has a universal value. We also discuss an old incomplete proof by Weyl which is important from an historical perspective. (shrink)

The Michelson-Morley experiment suggests the hypothesis that the two-way speed of light is constant, and this is consistent with a more general invariance than that of Lorentz. On adding the requirement that physical laws have the same form in all inertial frames, as Einstein did, the transformation specializes to that of Lorentz.

It is still perhaps not widely appreciated that in 1905 Einstein used his postulate concerning the ‘constancy’ of the light-speed in the ‘resting’ frame, in conjunction with the principle of relativity, to derive numerical light-speed invariance. Now a ‘weak’ version of the relativity principle (or, alternatively, appeal to the Michelson—Morley experiment) leads from Einstein's light postulate to a condition that we call universal light-speed constancy. which is weaker than light-speed invariance. It (...) follows from earlier independent investigations (Robertson [1949]; Steigler [1952]; Tzanakis and Kyritsis [1984]) that this condition is none the less sufficient to derive the Lorentz transformations up to a scale factor, given the well-known kinematic principle of ‘reciprocity’. In this paper, we follow Robertson and explore the kinematics consistent with universal light-speed constancy without imposing reciprocity, and we recover the Lorentz transformations by further appeal only to the weak relativity principle and spatial isotropy. (shrink)

Nowadays, modernization, development and adaptation in society is more and more linked to primarily dromocratic teletopy, i.e. the ability and readiness to connect to networks. The process of modernization received a new and powerful impetus over the last decade. This impetus is increasing the speed of information translation (transfer). However inseparable from networks and meta-networks speed is, it can be studied relatively independently in a given context, as indicated by P. Virilio in his dromologic research. Dromologic research of (...) “man’s status in the world” shows that man – his perception, his language as well as his thinking is substantially changed by the speed of information translation. Virilio devoted a considerable part of his work to the changes of perception of reality. He studied how a new way of perception of reality is created owing to ever increasing speed of sequential information transfer, how new aesthetics – aesthetics of disappearing – is formed thanks to cinematographic (i.e. visualized) division. The following text aims at showing that ethics, those issues concerning moral values, ethical standpoints and substantiations of various social dilemmas and conflicts overnight have rapidly ended up in a new element created by the speed of information transfer in networks. (shrink)

We examine the process of the emission of light from an atom that is in a relative translational motion with respect to the medium at rest in which the electromagnetic excitations propagate. The effect of Lorentz contraction of the of electron orbits on the emitted frequency is incorporated in the Rydberg formula, as well as the emitter’s Doppler effect is acknowledged. The result is that the frequency of the emitted light is modified by a factor that is identical (...) with what is called the ‘relativistic Doppler effect’. The new emission formula is applied for reinterpretation of the Ives-Stilwell experiment and shown that within the second order of approximation with respect to the speeds of the atom and the ‘absolute speed’ (Earth’s speed relative to the medium), the absolute motion does not affect the interference. The expression for the modification of the frequency involves both a first and a second-order term with respect to the speed of the atoms in the cathode tube. The latter turns out to be quantitatively the same as if the time would have changed its rate in the frame moving with the atoms. Thus, a new interpretation of the results of this famous experiment is provided without stipulating time dilation. (shrink)

A unique guide to creative shutter speed techniques, illustrated with striking full-color examples Along with available light and aperture, shutter speed is one of the variables that determine exposure–the amount of light that reaches the camera's sensor. Set on automatic modes, cameras typically attempt to reduce or eliminate blur in a picture. But by manipulating shutter speed creatively, photographers can achieve a range of striking motion blur or stop-action effects. Using an array of inspiring photographs (...) depicting people, wildlife, and landscapes, Creative Power of Shutter Speed explains how to "read" the light and movement in a potential photograph and identify the best shutter speed for the desired effect. (shrink)

In Einstein's theory of relativity, the speed of light is deemed an absolute value because it is indifferent to the motion of material bodies. Nothing we do can "take a bite" out of its measured velocity of 186,000 miles per second: it is an irreducible quantity. Similarly, our minds cannot race ahead quickly enough to reduce or convert light to everyday understandings. Indeed, modem physics portrays light as having an infinite aspect. Leading to talk of the (...) spaceless, timeless character of light, this aspect permits the suggestion that light resonates spiritual possibilities, and this resonance supports the traditional religious view that light is a symbol or expression of divinity. It also provides a basis for affirming absolutes in ethical life. The relativist stance is thus countered on two fronts—scientific and sacred—with light shining through the veil or barrier that has historically divided the two. (shrink)

We analyze the possible implications of spacetime discreteness for the special and general relativity and quantum theory. It is argued that the existence of a minimum size of spacetime may explain the invariance of the speed of light in special relativity and Einstein’s equivalence principle in general relativity. Moreover, the discreteness of spacetime may also result in the collapse of the wave function in quantum mechanics, which may provide a possible solution to the quantum measurement problem. These interesting (...) results might have some important implications for a complete theory of quantum gravity. (shrink)

Light is puzzling in modern physics–witness wave-particle duality, the two-slit experiment, and the invariant speed of light. These puzzles are not intrinsic to light but arise from overly narrow views of light. Disregarding the expansive, unitary nature of light that informs everyday experience, modern physics treats light as if it were self-bounded and separable. Further, physics assumes that light is not complicit with observations of light, that the two are separable. By (...) likening light to light-illuminated entities, these attitudes set the stage for puzzles. When,however, conceptions of light are aligned with visual experience, those puzzles become occasions of understanding.This is because visual experience already embodies that aspect of light which physics finds so anomalous: nonseparability. Light's interactive vastness shows up wherever light shows up, and because no observer can back away from light or step outside its integrative embrace, different parts of light cannot be lifted out ofthe observation as distinct – i.e., distinctly-observed – entities. (shrink)

An operational approach to quantum mechanics has been developed in the past decades in our group in Brussels. A similar approach is taken in this work, making use of the extra operational depth offered by this approach, to show that the construction of spacetime is specific to each observer. What is usually referred to as the block universe then emerges by noting that parts of the past and future are also contained in the present, but without the limitations that a (...) four-dimensional block universe usually implies, of a reality in which change would be impossible. In our operational approach, reality remains dynamic, with free choice playing a central role in its conceptualization. We also show that, when operationally analyzed, the theory implies that objects move not only in space, but also and especially in time, and more generally in spacetime, with their rest mass being a measure of their kinetic time energy. We therefore claim that Einstein’s relativity revolution has not been fully realized, since most physicists are not ready to accept these consequences of the theory although the formula’s showing them, when operationally analyzed, are in every relativity textbook. In particular, when relativistic motion is revisited as a genuine four-dimensional motion, it becomes possible to reinterpret the parameter c associated with the coordinate speed of light, which becomes the magnitude of the four-velocity of all material entities. We observe that this four-dimensional motion in Minkowski space can also be better understood if placed in the broader perspective of quantum mechanics, provided that non-locality is interpreted as non-spatiality, thus indicating the existence of an underlying non-spatial reality, the nature of which could be conceptual, consistent with the conceptuality interpretation of quantum mechanics. This hypothesis is reinforced by noting that when observers, or experiencers, as they will be referred to in this article, are described by acknowledging their cognitive nature of entities moving in a semantic space, Minkowski metric emerges in a natural way. (shrink)

The two center time dependent Dirac equation, for an electron in the external field of two colliding ultrarelativistic heavy ions is considered. In the ultrarelativistic limit, the ions are practically moving at the speed of light and the electromagnetic fields of the ions are confined to the light fronts by the extreme Lorentz contraction and by the choice of gauge, designed to remove the long-range Coulomb effects. An exact solution to the ultrarelativistic limit of the two-center Dirac (...) equation is found by using light-front variables and a light-fronts representation. Previously unexplained experimental results obtained at CERN's SPS are explained in this way and predictions are made as to where one should look, in momentum space, and in space-time, if one wants to study and observe non-perturbative electromagnetic pair-production effects in extremely relativistic heavy-ion collisions. (shrink)

This paper (i) gives necessary and sufficient conditions that clocks in an inertial lattice can be synchronized, (ii) shows that these conditions do not imply a universal light speed, and (iii) shows that the terrestrial redshift experiment provides evidence that clocks in a small inertial lattice in a gravitational field can be synchronized.

This essay, suggesting two physical phenomena that might serve as meaningful analogies to divine transcendence, is a theological complement to two earlier Zygon articles that show how the underlying ubiquity of electromagnetic phenomena in all of nature is a compelling physical analogy to divine immanence. My perception of transcendence and its relation to immanence are specified to provide a context for the discussion. A description of our being ensconced in what I term a cosmic cocoon introduces the discussion of how (...) the finite limit of the speed of light and quantum non‐locality could be considered as physical analogies of, or pointers to, God's transcendence. The relevance of our cosmologic future to transcendence is also treated. Selected examples of transcendence found in spiritual experiences and in religious scriptures are presented that complement the physical discussion. Finally, the relevance of this study to a theology of nature as well as a natural theology is examined. (shrink)

From the comparison of time in inertial frames, possible types of transformations between inertial frames are deduced. This elementary deduction directly relates the properties of time with the type of transformations. When all inertial frames measure the same time (time is absolute), the transformations are Galilean. When each inertial frame has its own time, different from the times of other inertial frames (time is not invariant) the transformations are Lorentz-like with the same positive parameter k. The parameter k is the (...) supremum of possible velocities in an inertial frame, the same for all inertial frames. Einstein's postulate about the invariance of the speed of light says more: there is a uniform motion with the supremum k, which is exactly the motion of light in a vacuum. At the end of the article, attempts to reduce the special theory of relativity to the principle of relativity are criticized. (shrink)

The role of the light postulate in special relativity is reexamined. The existing theory of relativity without light shows that one can deduce Lorentz-like transformations with an undetermined invariant speed based on homogeneity of space and time, isotropy of space and the principle of relativity. However, since the transformations can be Lorentzian or Galilean, depending on the finiteness of the invariant speed, a further postulate is needed to determine the speed in order to establish a (...) real connection between the theory and special relativity. In this paper, I argue that a certain discreteness of space-time, whose existence is strongly suggested by the combination of quantum theory and general relativity, may result in the existence of a maximum and invariant speed when combing with the principle of relativity, and thus it can determine the finiteness of the speed in the theory of relativity without light. According to this analysis, the speed constant c in special relativity is not the actual speed of light, but the ratio between the minimum length and the shortest time of discrete space-time. This suggests a more complete theory of relativity, the theory of relativity in discrete space-time, which is based on the principle of relativity and the constancy of the minimum size of discrete space-time. (shrink)

This concise book introduces nonphysicists to the core philosophical issues surrounding the nature and structure of space and time, and is also an ideal resource for physicists interested in the conceptual foundations of space-time theory. Tim Maudlin's broad historical overview examines Aristotelian and Newtonian accounts of space and time, and traces how Galileo's conceptions of relativity and space-time led to Einstein's special and general theories of relativity. Maudlin explains special relativity using a geometrical approach, emphasizing intrinsic space-time structure rather than (...) coordinate systems or reference frames. He gives readers enough detail about special relativity to solve concrete physical problems while presenting general relativity in a more qualitative way, with an informative discussion of the geometrization of gravity, the bending of light, and black holes. Additional topics include the Twins Paradox, the physical aspects of the Lorentz-FitzGerald contraction, the constancy of the speed of light, time travel, the direction of time, and more.Introduces nonphysicists to the philosophical foundations of space-time theory Provides a broad historical overview, from Aristotle to Einstein Explains special relativity geometrically, emphasizing the intrinsic structure of space-time Covers the Twins Paradox, Galilean relativity, time travel, and more Requires only basic algebra and no formal knowledge of physics. (shrink)