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This method synchronizes distant clocks in such a way that the one-way speed of light becomes equal to the two-way speed of light. If a signal sent from A at time t 1 {\displaystyle t_{1}} is arriving at B at time t 2 {\displaystyle t_{2}} and coming back to A at time t 3 {\displaystyle t_{3}} , then the following convention applies:
t 2 = t 1 + 1 2 ( t 3 − t 1 ) {\displaystyle t_{2}=t_{1}+{\tfrac {1}{2}}\left(t_{3}-t_{1}\right)} .
The details of this method, and the conditions that assure its consistency are discussed in Einstein synchronization.
As demonstrated by Hans Reichenbach and Adolf Grünbaum, Einstein synchronization is only a special case of a more broader synchronization scheme, which leaves the two-way speed of light invariant, but allows for different one-way speeds. The formula for Einstein synchronization is modified by replacing 1⁄2 with ε:
t 2 = t 1 + ε ( t 3 − t 1 ) . {\displaystyle t_{2}=t_{1}+\varepsilon \left(t_{3}-t_{1}\right).}
ε can have values between 0 and 1. It was shown that this scheme can be used for observationally equivalent reformulations of the Lorentz transformation, see Generalizations of Lorentz transformations with anisotropic one-way speeds.
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↑ http://arxiv.org/abs/1201.1828
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↑ Nelson (1992). “Experimental comparison of time synchronization techniques by means of light signals and clock transport on the rotating earth”. Proceedings of the 24th PTTI meeting 24: 87–104.
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↑ Iyer, Chandru; Prabhu, G. M. (2010). “A constructive formulation of the one-way speed of light”. American Journal of Physics 78 (2): 195–203. arXiv:1001.2375. Bibcode: 2010AmJPh..78..195I. doi:10.1119/1.3266969.
↑ Greaves, E. D.; Rodríguez, An Michel; Ruiz-Camacho, J. (2009), “A one-way speed of light experiment”, American Journal of Physics 77 (10): 894–896, Bibcode: 2009AmJPh..77..894G, doi:10.1119/1.3160665
↑ Hankins A.; Rackson C.; Kim W. J. (2013), “Photon charge experiment”, Am. J. Phys. 81 (6): 336–441
↑ Finkelstein, J. (2009), “One-way speed of light?”, American Journal of Physics 78 (8): 877, arXiv:0911.
Changing the convention of synchronization for A and B makes the value for time dilation (like the one-way speed of light) directional dependent. The same conventionality also applies to the influence of time dilation on the Doppler effect. Only when time dilation is measured on closed paths, it is not conventional and can unequivocally be measured like the two-way speed of light. Time dilation on closed paths was measured in the Hafele–Keating experiment and in experiments on the Time dilation of moving particles such as Bailey et al. (1977). Thus the so-called twin paradox occurs in all transformations preserving the constancy of the two-way speed of light.