Concepts of Simultaneity
From Antiquity to Einstein and Beyond
Publication Year: 2006
Published by: The Johns Hopkins University Press
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Quite a few notions in the physical sciences, such as “force” or “mass,” are used in everyday language before becoming rigorously defined scientific concepts or technical terms. Only one concept of this kind, however, played a critical role in initiating a new physical theory that has fundamentally changed all our conceptions of physical reality...
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Modern physics, as is well known, led to a radical revision of the fundamental concepts of classical physics, such as the concepts of space, time, matter, energy, and causality. The foundations of modern physics are the quantum theory and the theory of relativity, both of which originated in the early years of the twentieth century...
1 Terminological Preliminaries
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For the sake of verbal consistency and the prevention of possible misinterpretations it is desirable, if not necessary, to begin our study with some terminological comments. The topic of the present chapter is therefore primarily not the concept of simultaneity but rather the word or the verbal expression that denotes this concept. As far as semantic considerations are involved...
2 The Concept of Simultaneity in Antiquity
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It is often said that the language of science is an extension or refinement of the language of ordinary life, because scientific concepts, no matter how sophisticated they may be, must ultimately be explainable by means of concepts used in the ordinary experiences of daily life. This is certainly true for the scientific concept of simultaneity because the term “simultaneous” was used...
3 Medieval Conceptions of Simultaneity
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In the writings of the early medieval philosophers metaphysical speculations were inextricably intermingled with theological ideas. This fusion of the conclusions of reason with the facts of revelation was characteristic for the patristic philosophers, in particular, who were thought to have recognized similarities between Plato and the Judeo-Christian tradition...
4 The Concept of Simultaneity in the Sixteenth and Seventeenth Centuries
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Three important innovations in the sixteenth and the seventeenth centuries led to a far-reaching revision of the concept of time and with it of the concept of simultaneity: (1) the philosophical abandonment of the Aristotelian association of the concept of time with that of motion, (2) the widespread technical use of mechanical clocks, and (3) the scientific discovery...
5 The Concept of Simultaneity in Classical Physics
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The prehistory of the classical or Newtonian conception of time, and with it of simultaneity, did not start with Gassendi’s revision of the Aristotelian theory of time. It can at least be traced back to the kinematical theories of the so-called Calculatores of the Merton School in Oxford, which flourished in the early fourteenth century. One may even claim that, strictly speaking...
6 The Transition to the Relativistic Conception of Simultaneity
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Modern science and, in particular, modern physics—and with it the modern conceptions of simultaneity—are deeply indebted to several intellectual developments of the nineteenth century. Foremost among these was the discovery of non-Euclidean geometry. By abolishing the monopoly of Euclidean geometry this discovery stimulated an intense interest in critically re-examining...
7 Simultaneity in the Special Theory of Relativity
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From Albert Einstein’s letters, written between 1898 and 1902 to his fiancée Mileva Maric, we know that as a student Einstein had already been deeply interested in the ether theories of electrodynamics and in the problem of the detectability of the Earth’s motion through the supposedly immobile ether. We also know from his correspondence...
8 The Reception of the Relativistic Conception of Simultaneity
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Einstein’s definition of distant simultaneity had far-reaching consequences. It led not only to a new conception of time, which in itself would have been a major innovation, but also to a radical break with classical physics and philosophy. First, the definition implies the renunciation of the previously generally accepted idea that there is no upper limit to physically attainable velocities...
9 The Conventionality Thesis
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The authors of the early articles and textbooks on relativity in general emphasized the importance of the concept of simultaneity for the construction of the time coordinate of an inertial reference system but rarely paid attention to the conventionality of its definition. A typical example is Max von Laue...
10 The Promulgation of the Conventionality Thesis
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It was only in the late 1950s that Reichenbach’s philosophy of space and time, and his thesis of the conventionality of simultaneity, found the attention they deserve. An important factor in this development was the publication of his Philosophie der Raum-Zeit-Lehre in an English translation by his wife Maria Reichenbach...
11 Symmetry and Transitivity of Simultaneity
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12 Arguments against the Conventionality Thesis
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As stated in chapter 7, in his 1905 paper on relativity, Einstein “assumed” that clock synchronization or simultaneity are symmetric and transitive relations,1 and he defined the “time” of a reference system in terms of the notion of simultaneity. Because of the importance of the relation between these two notions, the “time of a reference system,”...
13 Clock Transport Synchrony
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The use of the transport of clocks for the establishment of distant simultaneity is as old as the invention of portable timepieces. As we saw in chapter 4, transported clocks had been used in the sixteenth century, for example, by the Flemish cartographer Reinerus Gemma, for the determination of the geographic longitude of a certain location. Still in 1904 Henri Poincar�...
14 Recent Debates on the Conventionality of Simultaneity
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An important publication supporting the conventionality thesis of distant simultaneity is W. F. Edwards’s 1963 paper on the special theory of relativity based on nonstandard synchrony.1 It shows that the Lorentz transformations can be generalized by admitting anisotropic light propagation and yet be observationally equivalent to those conventionally constructed...
15 Simultaneity in General Relativity and in Quantum Mechanics
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In contrast to the voluminous literature on the notion of distant simultaneity in the special theory of relativity, the study of this concept in the general theory of relativity, or only in noninertial space–time systems, has been given rather limited attention. One reason is that a serious study of this subject requires some knowledge of the tensor calculus and differential geometry...
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Page Count: 320
Illustrations: 16 line drawings
Publication Year: 2006