If it was striking that Newton spoke more about space than about time, Einstein appears to have actually given time a crucial role,133 since the key that opened his way to a new understanding of basic physical concepts was precisely an analysis of the concept of time. Einstein recognized that the concept of absolute time was useless because the presupposed synchronization of clocks using effects that expand at extreme velocity cannot be implemented due to the finite nature of the speed of light. He speaks of a relative simultaneity instead. This relative simultaneity means that, in reference systems that are inert relative to one another, the simultaneity determined by using light signals completely corresponds to the traditional conceptions.134 The study of moving systems, however, resulted in entirely different findings, which makes it impossible to speak of a simultaneity of two events in a sense that is valid for all reference systems. In this case, relative simultaneity must be understood in such a way that a certain Observer A characterizes two events as simultaneous, while an Observer B, moved in relationship to A, calls these events nonsimultaneous. This makes it necessary to trans fer not only the place coordinates, but also the time coordinates, during a transition from one inertial system135 to another. In the everyday sphere of perception, that which is simultaneously observed also appears to happen simultaneously. However, consideration of the finite nature of the spreading speed of light forces one to distinguish between time and local time. This distinction nullifies the identity of simultaneous observation and simultaneous event.136
Thus, at the beginning of the special theory of relativity, there is an analysis of the concept of time with the insight that time cannot be defined absolutely, since there is an indissoluble connection between time and the speed with which a signal can travel.137 In the end, Einstein says, "[t]he theory of relativity may indeed be said to have put a sort of finishing touch to the mighty intellectual edifice of Maxwell and Lorentz, inasmuch as it seeks to extend field physics to all phenomena, gravitation included."138
Initially, however, Einstein did not wish to have his theory characterized as a closed system, but rather as a heuristic principle. This means that individual laws are not contained in the theory of relativity and cannot be derived from it by means of deduction, but rather that the theory of relativity in the sense of a metatheory specifies correlations between laws and the presuppositions that are to be fulfilled by them.139 Therefore, he spoke initially only of a "principle of relativity."140 The term theory of relativity, which gained acceptance beginning in 1907, was proposed by other people and subsequently accepted only reluctantly by Einstein.141 The term theory possibly led to a popular understanding in the sense of "everything is relative." Especially after the general theory of relativity became known, there was ample breeding ground for such a misunderstanding because of the political and cultural conditions of the times, although, with regard to contents, one is in fact dealing, quite the contrary, with the invariance and universality of the absolute speed of light;142 the causality in Einstein's theory is no less rigorous than that in Newton's.143
In other words: The absoluteness of the speed of light has replaced the absoluteness of space and time. The boundary of the light barrier cannot be crossed from any side. Thus, the constancy of the speed of light in a vacuum determines the boundary for the expansion of every effect. The speed of light limits the observable universe, not only with regard to space, but also with regard to time, by permitting access only to a limited past. It also restricts the scope of knowledge that could, for example, reach us within a lifetime from extraterrestrial civilizations.144 From the constancy of the speed of light follows the constancy of the four-dimensional space-time interval between two events; space and time can each vary, but the interval as a whole remains the same for all observers, independent of their relative speed. In this network of relationships and boundaries, time no longer has an independent existence; it appears—as in Leibniz—to be a way of ordering matter that has no physical meaning without changes in the relationships of objects.145
In addition to the constancy of the speed of light in the vacuum, Einstein built on the postulate of the validity of the same laws of nature in all systems moving uniformly towards one another.146 However, even before then, in agreement with the Michelson-Morley experiment, the result of which "was a verdict of 'death' to the theory of a calm ether-sea through which all matter moves,"147 Einstein had eliminated the "'enfant terrible' of the family of physical substances"148 and basically dropped the ether concept. The two presuppositions for Einstein's special theory of relativity produce a contradiction to the classical transformation. For high speeds, it is easy to show that the Galilean Transformation of classical mechanics is inapplicable.149 While the experiences gained through classical mechanics definitely retain their validity for low speeds compared to the speed of light, speeds that approximate the speed of light require the Lorentz Transformation. This transformation predicts that a rod moved at high speed will shrink in the direction of motion, and a clock moved in the same way will slow its pace (time dilatation). At the speed of light, the rod would disappear, and the clock would stop.150 The equations of the Lorentz-Transfor-
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