Roy Wood Sellars (1880–1973) is often reduced to his role as father of Wilfrid Sellars. This is unfair because during the 1920s, ‘30s, and ‘40s, Roy Wood was one of the leading figures of the then prevailing American realist movement. In the present paper, I will focus on one particular facet of R. W. Sellars’ philosophical approach: his continual examination of Albert Einstein’s special theory of relativity. I shall primarily reconstruct his discussion of Einstein’s theory, as it can (...) be found in his seminal The Philosophy of Physical Realism (1932). In contrast to authors such as Bertrand Russell or Émile Meyerson, Sellars refused to interpret special relativity in a realist vein. In his view, it should be seen as an “ars mensurandi” and thus being interpreted purely operationally. As with Einstein himself, the concept of simultaneity was his paradigm case in point. However, Sellars opined that besides the physical (mensurational) concepts of time and simultaneity there also exists an ontological understanding of these notions. “Real” time and “absolute” simultaneity are, according to Sellars, the indispensable non-relativistic counterparts to Einstein’s respective relativistic conceptions. They are to be interpreted realistically since they prove, Sellars maintains, to be explanatory regarding events in Einstein-Minkowski’s world. In the course of the paper, I shall compare this view with the one defended by Henri Bergson. Furthermore, Sellars’ later approach from the 1940s and ‘50s will be briefly considered and critically discussed by confronting it with more recent attempts at ontologically ‘grounding’ special relativistic kinematics. (shrink)

The book opens with a description of the smooth transition from Newtonian to Einsteinian behaviour from electrons as their energy is progressively increased, ...

This book gives an excellent introduction to the theory of special relativity. Professor Resnick presents a fundamental and unified development of the subject with unusually clear discussions of the aspects that usually trouble beginners. He includes, for example, a section on the common sense of relativity. His presentation is lively and interspersed with historical, philosophical and special topics (such as the twin paradox) that will arouse and hold the reader's interest. You'll find many unique features that (...) help you grasp the material, such as worked-out examples,summary tables,thought questions and a wealth of excellent problems. The emphasis throughout the book is physical. The experimental background, experimental confirmation of predictions, and the physical interpretation of principles are stressed. The book treats relativistic kinematics, relativistic dynamics, and relativity and electromagnetism and contains special appendices on the geometric representation of space-time and on general relativity. Its organization permits an instructor to vary the length and depth of his treatment and to use the book either with or following classical physics. These features make it an ideal companion for introductory courses. (shrink)

The first completely geometric approach to relativity theory, based on the space-time geometries of Loedel and Brehme.

The structure of the Lorentz transformation depends intimately on the conventional operations for measurement of lengths (L) and time intervals (T). The prescription for length measurement leads to justifiable utilization of Euclidean geometry over finite values of the coordinates. Then T-values can be regarded as ratios of length measurements within a suitably defined clock. In certain cases the synchronization process should be supplemented by measurements providing position certification. The Lorentz transformation emerges from three specific symmetry statements, assured by the nature (...) of the L and T operations: (1) one-one correspondence of finite values of the coordinates of two inertial frames, (2) frame reciprocity, and (3) spatial isotropy. (Light signaling is not needed in this derivation. Afterward, it is assumed that light is indeed an agent moving with the common speed revealed by the transformation.) When rest masses have been determined in the conventional fashion, the conservation of momentum and of energy follow from the kinematics—a result due to Einstein. (shrink)

In this paper I expound an argument which seems to establish that probabilism and special relativity are incompatible. I examine the argument critically, and consider its implications for interpretative problems of quantum theory, and for theoretical physics as a whole.

Special relativity is based on the apparent contradiction between two postulates, namely, Galilean vs. c-invariance. We show that anomalies ensue by holding the former postulate alone. In order for Galilean invariance to be consistent, it must hold not only for bodies’ motions, but also for the signals and forces they exchange. If the latter ones do not obey the Galilean version of the Velocities Addition Law, invariance is violated. If, however, they do, causal anomalies, information loss and conservation (...) laws’ violations are bound to occur. These anomalies are largely remedied by introducing waves and fields that disobey Galilean invariance. Therefore, from these inconsistencies within classical mechanics, electromagnetism could be predicted before experiment proved its existence. Special relativity, it might be argued, would then follow naturally, either as a resolution of the resulting conflict or as an extrapolation of the path between the theories. We conclude with a review of earlier attempts to base SR on a single postulate, and point out the originality of the present work. (shrink)

In a comparison of the principles of special relativity and of quantum mechanics, the former theory is marked by its relative economy and apparent explanatory simplicity. A number of theorists have thus been led to search for a small number of postulates - essentially information theoretic in nature - that would play the role in quantum mechanics that the relativity principle and the light postulate jointly play in Einstein's 1905 special relativity theory. The purpose of (...) the present paper is to resist this idea, at least in so far as it is supposed to reveal the fundamental form of the theory. It is argued that the methodology of Einstein's 1905 theory represents a victory of pragmatism over explanatory depth; and that its adoption only made sense in the context of the chaotic state state of physics at the start of the 20th century - as Einstein well knew. (shrink)

In this paper, I defend a theory of local temporality, sometimes referred to as a point-present theory. This theory has the great advantage that it allows for the possibility of an open future without requiring any alterations to our standard understanding of special relativity. Such theories, however, have regularly been rejected out of hand as metaphysically incoherent. After surveying the debate, I argue that such a transformation of temporal concepts (i) is suggested by the indexical semantics of tense (...) in a relativistic universe, (ii) when properly understood easily withstands the usual accusations of metaphysical incoherence and (iii) leads naturally to a meta-philosophical position from which we can understand and escape the increasing sterility of debates between radical Parmenideans and radical Heracliteans in the philosophy of time. (shrink)

To comprehend the special relativity genesis, one should unfold Einstein’s activities in quantum theory first . His victory upon Lorentz’s approach can only be understood in the wider context of a general programme of unification of classical mechanics and classical electrodynamics, with relativity and quantum theory being merely its subprogrammes. Because of the lack of quantum facets in Lorentz’s theory, Einstein’s programme, which seems to surpass the Lorentz’s one, was widely accepted as soon as quantum theory became (...) a recognized part of physics. A new approach to special relativity genesis enables to broaden the bothering “Trinity” group of its creators to include Gilbert N. Lewis. Notwithstanding that the links necessarily existing between all the 1905 papers were obscured by Einstein himself due to the reasons discussed below, Lewis revealed from the very beginning the connections between special relativity and quasi-corpuscular theory of light, as he punctuated: “The consequences which one of us obtained from a simple assumption as to the mass of a beam of light, and the fundamental conservation of mass, energy and momentum, Einstein has derived from the principle of relativity and the electromagnetic theory” (Lewis G.N.& Tolman R.C. “The Principle of Relativity and Non-Newtonian Mechanics”, Philosophical Magazine, 1908). (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)

To make out in what way Einstein’s 1905 ‘annus mirabilis’ writings hang together one has to hang on Einstein’s strive for unity evinced in his stubborn attempts to coordinate with one another the basic research traditions of classical physics. Light quanta hypothesis and special theory of relativity turn out to be mere milestones of maxwellian electrodynamics and statistical thermodynamics reconciliation programme. The conception of luminiferous ether was an insurmountable stumbling block for Einstein’s statistical thermodynamics programme in which (...) the leading role was played by the light quanta paper . (shrink)

Special relativity provides the foundations of our knowledge of space and time. Without it, our understanding of the world, and its place in the universe, would be unthinkable. This book gives a concise, elementary, yet exceptionally modern, introduction to special relativity. It is a gentle yet serious 'first encounter', in that it conveys a true understanding rather than purely reports the basic facts. Only very elementary mathematical knowledge is needed to master it, yet it will leave (...) the reader with a sound understanding of the subject. Special Relativity: A First Encounter starts with a broad historical introduction and motivation of the basic notions. The central chapters are dedicated to special relativity, mainly following Einstein's historical route. Later chapters turn to various applications in all parts of physics and everyday life. Unlike other books on the subject, the current status of the experimental foundations of special relativity is accurately reported and the experiments explained. This book will appeal to anyone wanting a introduction to the subject, as well as being background reading for students beginning a course in physics. (shrink)

McTaggart distinguished two conceptions of time: the A-series, according to which events are either past, present or future; and the B-series, according to which events are merely earlier or later than other events. Elsewhere, I have argued that these two views, ostensibly about the nature of time, need to be reinterpreted as two views about the nature of the universe. According to the so-called A-theory, the universe is three dimensional, with a past and future; according to the B-theory, the universe (...) is four dimensional. Given special relativity (SR), we are obliged, it seems, to accept (a modified version of) the B-series, four dimensional view, and reject the A-series, three dimensional view, because SR denies that there is a privileged, instantaneous cosmic "now" which seems to be required by the A-theory. Whether this is correct or not, it is important to remember that the fundamental problem, here, is not "What does SR imply?", but rather "What is the best guess about the ultimate nature of the universe in the light of current theoretical knowledge in physics?". In order to know how to answer this question, we need to have some inkling as to how the correct theory of quantum gravity incorporates quantum theory, probability and time. This is, at present, an entirely open question. String theory, or M-theory, seems to evade the issue, and other approaches to quantum gravity seem equally evasive. However, if probabilism is a fundamental feature of ultimate physical reality, then it may well be that the A-theory, or rather a closely related doctrine I call “objectism”, is built into the ultimate constitution of things. (shrink)

Recently we presented a new special relativity theory for cosmology in which it was assumed that gravitation can be neglected and thus the bubble constant can be taken as a constant. The theory was presented in a six-dimensional hvperspace. three for the ordinary space and three for the velocities. In this paper we reduce our hyperspace to four dimensions by assuming that the three-dimensional space expands only radially, thus one is left with the three dimensions of ordinary space (...) and one dimension of the radial velocity. (shrink)

This book presents an elementary but complete exposition of the relativistic theory of the measurement of intervals in space & time.

In Mundy [a] I offered an axiomatic analysis of the physical content of the kinematics of special relativity which suggests that, contrary to common belief, there is no incompatibility between special relativity and spacelike (faster-than-light) causation. An anonymous referee pointed out that this conclusion might have some bearing on problems in the interpretation of quantum mechanics such as the Einstein-Podolsky-Rosen problem, since one line of solution to these problems involves the postulation of spacelike causal processes. The (...) present note will develop this idea. (shrink)

It will be shown that, in comparison with the pre-relativistic Galileo-invariant conceptions, special relativity tells us nothing new about the geometry of spacetime. It simply calls something else "spacetime", and this something else has different properties. All statements of special relativity about those features of reality that correspond to the original meaning of the terms "space" and "time" are identical with the corresponding traditional pre-relativistic statements. It will be also argued that special relativity and (...) Lorentz theory are completely identical in both senses, as theories about spacetime and as theories about the behavior of moving physical objects. (shrink)

New four coordinates are introduced which are related to the usual space-time coordinates. For these coordinates, the Euclidean four-dimensional length squared is equal to the interval squared of the Minkowski space. The Lorentz transformation, for the new coordinates, becomes an SO(4) rotation. New scalars (invariants) are derived. A second approach to the Lorentz transformation is presented. A mixed space is generated by interchanging the notion of time and proper time in inertial frames. Within this approach the Lorentz transformation is a (...) 4-dimensional rotation in an Euclidean space, leading to new possibilities and applications. (shrink)

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)

In recent work, David Chalmers argues that “Edenic shapes”—roughly, the shape properties phenomenally presented in spatial experience—are not instantiated in our world. His reasons come largely from the theory of Special Relativity. Although Edenic shapes might have been instantiated in a classical Newtonian world, he maintains that they could not be instantiated in a relativistic world like our own. In this essay, I defend realism about Edenic shape, the thesis that Edenic shapes are instantiated in our world, against (...) Chalmers’s challenge from Special Relativity. I begin by clarifying the notion of an Edenic shape by reference to Chalmers’s notion of the “Edenic” content of perceptual experience. I then reconstruct Chalmers’s argument that Edenic shapes could not be instantiated in a relativistic world. His reasoning proceeds from two assumptions. The first is that the only shape properties instantiated in a relativistic world are those which somehow involve relations to frames of reference. This is thought to follow from the phenomenon of Lorentz contraction, a consequence of Special Relativity. The second assumption is that Edenic shapes do not involve relations to frames of reference. One reason to accept the second assumption is that it seems that Edenic shapes could be instantiated in a classical Newtonian world, where the notion of a frame-relative shape has no meaningful application. I then proceed to defend RES against Chalmers’s argument by arguing that Special Relativity, properly understood, provides no support for Chalmers’s first assumption. More generally, I argue, by way of a careful analysis of the geometric structure of Minkowski space–time and Galilean space–time Newtonian physics), that Edenic shapes are no less at home in a relativistic world than in a classical Newtonian world. (shrink)

What is simultaneous with an event is what can interact with it; events have duration; therefore, any given event has distant events simultaneous with it, even according to Special Relativity. Consequently, the extension of our pre-relativistic judgments of distant simultaneity are largely preserved.

This paper shows how key aspects of Aristotle’s core concepts of matter and motion, some of which have recently been shown to help make sense of quantum mechanical indeterminacy, align with some important results of the energy-momentum relationship of special relativity. In this conception, mobility and indeterminacy are inherently linked to each other and to materiality. Applying these ideas to massless particles, which relativity tells us move at the maximal cosmic speed, allows us to draw the conclusion (...) that they must be the most basic physical bodies, that is, mobile substances. The most familiar massless particle, the photon, constitutes light. Furthermore, because the photon composes luminous matter but cannot be decomposed into anything else more basic, it fulfills the definition of element. (shrink)

In this paper, we explicitly point out the reasons why Special Relativity must be considered as the source of electron deep orbits, and dominates their behavior. We show that the cause is the quadratic form of the relativistic expression of energy, and this clearly appears when we explicitly develop the relativistic Schrödinger equation and compare it with the non-relativistic one.

Special relativity has changed the fundamental view on space and time since Einstein introduced it in 1905. It substitutes four dimensional spacetime for the absolute space and time of Newtonian mechanics. It is believed that the validities of Lorentz invariants are fully confirmed empirically for the last one hundred years and therefore its status are canonical underlying all physical principles. However, spacetime metric is a geometric approach on nature when we interpret the natural phenomenon. A geometric flaw on (...) this will be exhibited and the alternative is suggested. The reasonable geometric model of space and time is a three dimensional space which is translating along the time direction. This model legitimately represents the true characteristic of nature. (shrink)

With the interaction interpretation, the Lorentz transformation of a system arises with selection from a superposition of its states in an observation-interaction. Integration of momentum states of a mass over all possible velocities gives the rest-mass energy. Static electrical and magnetic fields are not found to form such a superposition and are to be taken as irreducible elements. The external superposition consists of those states that are reached only by change of state of motion, whereas the internal superposition contains all (...) the states available to an observer in a single inertial coordinate system. The conjecture is advanced that states of superposition may only be those related by space-time transformations (Lorentz transformations plus space inversion and charge conjugation). The continuum of external and internal superpositions is examined for various masses, and an argument for the unity of the super-positions is presented. (shrink)

We study the acceleration and collisions of rigid bodies in special relativity. After a brief historical review, we give a physical definition of the term ‘rigid body’ in relativistic straight line motion. We show that the definition of ‘rigid body’ in relativity differs from the usual classical definition, so there is no difficulty in dealing with rigid bodies in relativistic motion. We then describe The motion of a rigid body undergoing constant acceleration to a given velocity.The acceleration (...) of a rigid body due to an applied impulse.Collisions between rigid bodies. (shrink)

This white paper aims to identify an open problem in 'Quantum Physics and the Nature of Reality' -namely whether quantum theory and special relativity are formally compatible-, to indicate what the underlying issues are, and put forward ideas about how the problem might be addressed.

Special Relativity can be based on the whole proper group of both ortho- and antichronous Lorentz transformations, and a clear physical meaning can be given also to antichronous (i.e., nonorthochronous) Lorentz transformations. From the active point of view, the latter requires existence, for any particle, of its antiparticle within a purely relativistic, classical context. From the passive point of view, they give rise to frames “dual” to the ordinary ones, whose properties—here briefly discussed—are linked with the fact that (...) in relativity it is impossible to teach another, far observer (by transmitting only instructions, and no physical objects) our own conventions about the choices right/left, matter/antimatter, and positive/negative time direction. Interesting considerations follow, in particular, by considering—as it is the case—theCPT operation as an actual (even if antichronous) Lorentz transformation. (shrink)

The concept of an objective spatial direction in special relativity is investigated and theories assuming light-speed isotropy while accepting the existence of a privileged spatial direction are classified, including so-called very special relativity. A natural generalization of the proper time principle is introduced which makes it possible to devise non-optical experimental tests of spatial isotropy. Several common misunderstandings in the relativistic literature concerning the role of spatial isotropy are clarified.

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)

Concise, well-written treatment of epochal theory of modern physics covers classical relativity and the relativity postulate, time dilation, the twin paradox, momentum and energy, particles of zero mass, electric and magnetic fields and forces and more. Only high school math needed. Replete with examples, ideal for self-study.

According to a widespread view, Einstein’s definition of time in his special relativity is founded on the positivist verification principle. The present paper challenges this received outlook. It shall be argued that Einstein’s position on the concept of time, to wit, simultaneity, is best understood as a mitigated version of concept empiricism. He contrasts his position to Newton’s absolutist and Kant’s transcendental arguments, and in part sides with Hume’s and Mach’s empiricist arguments. Nevertheless, Einstein worked out a concept (...) empiricism that is considerably more moderate than what we find in the preceding empiricist tradition and early logical positivism. He did not think that the origin of concepts is in observations, but in conventions, and he also maintained a realist ontology of physical events, which he thought is necessary for his theory. Consequently, his philosophy of time in special relativity is not couched in terms of an anti-metaphysical verificationism. (shrink)

The interaction interpretation of special relativity theory (elaborated in Part I) is discussed in relation to quantum theory. The relativistic transformations (Lorentz processes) of physical variables, on the interaction interpretation, are observation-interaction dependent, just as are the physical values (eigenvalues) of systems described by quantum-theoretic state functions; a common, basic structure of the special relativity and quantum theories can therefore be presented. The constancy of the light speed is shown to follow from interaction-transformations of frequency and (...) wavelength variables. A parallelism is suggested between, on the one hand, the Lorentz-Clausius distinction for relativistic transformations, and, on the other, the distinction between observation-dependent and observation-independent natural processes. The empirical study of rates of macroscopic clocks can provide a critical test of the interaction interpretation and of a possible extension to gravitational time changes; the role of time as prior determinant of natural process is at issue. The Hafele-Keating observations are of general relativity effects on clocks in accelerated motion. (shrink)

Metaphysics, having long since recovered the logical positivist/empiricist objections that were supposed to signal its death, is once again coming under sustained criticism, and from a similar direction. Once it was realised that speculative systematic metaphysics needn’t be abandoned in light of empiricist scruples, metaphysics flourished. But it’s become increasingly clear that, even if the logical empiricists didn’t exactly get their objections right, there is something worrying about the evidential basis for contemporary metaphysics. Not that metaphysicians are unaware of this. (...) There is lots of recent activity in metametaphysics, and much of this research is more or less connected to worries about whether we can have evidence in favour of a metaphysical hypothesis. Roughly: there are alternative views according to which metaphysical disputes variously.. (shrink)

When do objects at different times compose a further object? This is the question of diachronic composition. The universalist answers, ‘under any conditions whatsoever’. Others argue for restrictions on diachronic composition: composition occurs only when certain conditions are met. Recently, some philosophers have argued that restrictions on diachronic compositions are motivated by our best physical theories. In Persistence and Spacetime and elsewhere, Yuri Balashov argues that diachronic compositions are restricted in terms of causal connections between object stages. In a recent (...) article, Nikk Effingham argues that the standard objections to views that endorse restrictions on composition do not apply to a view that restricts composition according to compliance with the laws of nature. On the face of it, such restrictions on diachronic composition preserve our common-sense ontology while eliminating from it scientifically revisionary objects that travel faster than the speed of light. I argue that these attempts to restrict diachronic composition by appealing to either causal or nomological constraints face insurmountable difficulties within the context of special relativity. I discuss how the universalist should best respond to Hudson’s argument for superluminal objects, and in doing so, I present and defend a new sufficient condition for motion that does not entail that such objects are in superluminal motion. 1 Introduction2 Diachronic Composition3 Diachronic Composition and Superluminal Objects4 Restricting Diachronic Composition5 Causal and Nomological Restrictions on Composition in a Relativistic Context6 Superluminal Objects and Motion7 Conclusion. (shrink)

In this essay I address the issue of whether Einstein's Special Theory of Relativity counts against a tensed or "A-series" understanding of time. Though this debate is an old one, it continues to be lively with many prominent authors recently arguing that a genuine A-series is compatible with a relativistic world view. My aim in what follows is to outline why Special Relativity is thought to count against a tensed understanding of time and then to address (...) the philosophical attempts to reconcile the two theories. I conclude that while modern physics on its own does not rule out the possibility of a real A-series, the combination of Einstein's theory and the philosophical arguments against tense is decisive. The upshot is that the tenseless or "B-series" view of time is the best one. (shrink)

The Special Theory of Relativity and the Theory of the Electron have had an interesting history together. Originally the electron was studied in a non-relativistic context and this opened up the interesting possibility that lead to the conclusion that the mass of the electron could be thought of entirely in electromagnetic terms without introducing inertial considerations. However the application of Special Relativity lead to several problems, both for an extended electron and the point electron. These inconsistencies (...) have, contrary to popular belief not been resolved satisfactorily to date, even within the context of Quantum Theory. Thus they are not merely of historical interest. Nevertheless these and subsequent studies bring out the interesting result that Special Relativity (and the theory of the electron) breaks down within the Compton scale or when the Compton scale is not neglected. This again runs contrary to an uncritical notion that Special Relativity is valid for point particles. Furthermore, it is pointed out that experiments have been recently suggested to test these ideas. These considerations lead to a characterization of the Planck constant in classical terms. (shrink)

In this two-part essay, we distinguish several senses in which general relativity has been regarded as “locally special relativistic.” Here, in Part 1, we focus on senses in which a relativistic spacetime has been said to be “locally (approximately) Minkowskian.” After critiquing several proposals in the literature, we present a result capturing a substantive sense in which every relativistic spacetime is locally approximately Minkowskian. We then show that Minkowski spacetime is not distinguished in this result: every relativistic spacetime (...) is locally approximately every other spacetime in the same sense. In Part 2, we will consider “locally specially relativistic” matter theories. (shrink)