In the 1905 paper presenting the theory of special relativity (TSR) Einstein gave a nicely simple description of the clock paradox ideal experiment. He assumed that accelerations as such have no effect on the time marked by clocks. If the same idea is applied to the Sagnac effect, the SRT predicts zero differential retardation, that is, no effect. This is wrong.

Two spaceships accelerating equally from an initial (S) to a final (S�) inertial system, "spontaneously" modify their synchronization. If before acceleration the clocks aboard the spaceships gave c if used to measure the velocity of light, the same two clocks (not manipulated in any way) used again for the same measurement when at rest in S�, give a result different from c. Therefore the Lorentz transformations do not apply in passing from S to S�. This is also wrong.

Einstein�s 1918 treatment of the clock paradox introduced a gravitational potential of the fictitious forces, . In the usual ideal experiment, two spaceships A and B have aboard two clocks and and two observers and . According to has a strong action on , with opposite sign and double size of the velocity effect. But does not include in his calculation regarding . No doubt, also this is wrong. There is more.