Sagnac Effect: End of the Mystery
Transformations of space and time depending on a synchronisation parameter, e1, indicate the existence of a privileged inertial system S0. The Lorentz transformations are obtained for a particular e1 different from zero. No classical experiment on inertial frames depends on the choice of e1, but if accelerations are considered only e1 = 0 remains possible. The choice e1 = 0 provides a rational resolution of the long standing mystery connected with the relativistic interpretation of Sagnac effect.