Conventionality in Distant Simultaneity

Abstract

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 Grünbaum is thus either trivialized or refuted.

Synchronization Gauges and the Principles of Special Relativity

“…Briefly, Maxwell equations are covariant under synchronization changes, but optical anisotropy breaks their standard symmetric form: another unavoidable consequence of Selleri's inertial transformations (8).…”

“…In the late 1960's Ellis and Bowman [8], after careful synchronization of clocks by slow transport, argue that, although consistent nonstandard synchronization does not appear totally ruled out, there are sound physical reasons for preferring standard Einstein synchronization. Their conclusion is: "the thesis of the conventionality of distant simultaneity espoused particularly by Reichenbach and Grünbaum is thus either trivialized or refuted".…”

Generalized Edwards Transformation and Principle of Permutation Invariance

“…However, this needs a priori assumption of a universal limiting speed (e.g., a finite, constant speed or an infinitely large velocity) [7]. Someone may suggest that we can make use of the means of synchronizing clocks by slow transport, i.e., first one sets two clocks at one point (say, point A), and then carries one clock very slowly to another point (say, point B) [8]. But such a synchronization might be affected by the effects taking place when carrying the clock from point A to point B.…”

Testing Einstein’s Second Postulate with an Experiment of the Sagnac Type

“…One important contribution to the subject was given by Bell [10], who stated that although there is a stringent "difference in philosophy" between the view of SR and that of a preferred frame theory, "The facts of physics do not oblige us to accept one philosophy rather than the other". Bell's assertion was used as a starting point in a series of works adopting the conventionalist thesis within relativistic theories [10][11][12][13][14], where it has been argued that there is essentially one theory, Bell's two philosophies corresponding rather to different aspects of the same theory [11][12][13][14][15][16][17][18][19].…”