Time&Eternity

142 chapter 3
fer not only the place coordinates, but also the time coordinates, during a
transition from one inertial system 135 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