In his original paper of 1905, "On the Electrodynamics of Moving Bodies", Einstein described a procedure for synchronizing distant clocks at rest in any inertial system K. Clocks thus synchronized may be said to be in standard signal synchrony in K. It has often been claimed that there are no logical or physical reasons for preferring standard signal synchronizations to any of a range of possible non-standard ones. In this paper, the range of consistent non-standard signal synchronizations, first for any (...) one inertial system, and second for any set of such systems, is investigated, and it is shown that the requirement of consistency leaves much less room for choice than is commonly supposed. Nevertheless consistent non-standard signal synchronizations appear to be possible. However, it is also shown that good physical reasons for preferring standard signal synchronizations exist, if the Special Theory of Relativity yields correct predictions. The thesis of the conventionality of distant simultaneity espoused particularly by Reichenbach and Grunbaum is thus either trivialized or refuted. (shrink)

The conventionality of simultaneity at distant points is defended partly by reference to Einstein's 1905 paper founding special relativity. His famous light-signaling definition takes the transit time of light in one direction to be equal to that in the other. Conventionalists such as Reichenbach and Grunbaum argue that he could have made them unequal without denying any physical fact. However, Einstein's more detailed treatment in the 1910 Archives des sciences runs counter to this thesis. There he required that the two (...) signal-paths be physically equivalent and thus that whatever the signals travel through have no perturbing affect on their motions. (shrink)