Dear Georgina,
What about all putative evidence that confirms Einstein's SR, you might read Van Flandern, easily available at metaresearch.org. He argues that they altogether can be explained otherwise while nobody directly measured time dilation and nobody directly measured length contraction.
With ABA synchronization I refer to two objects A and B considered in the paper Zur Elektrodynamik bewegter Koerper 1905. I have only a copy in German at hands. For the sake of simplicity, lets restrict to motion along a straight line.
Einstein introduced two clocks. A first one at a point A located at the origin of a coordinate System K at rest is thought belonging to an observer who is in relative motion to the second clock carried by a point B whose coordinates also refer to K. This is already asymmetric because a person at B sees A within his own coordinate system k. As understood by Galilei, there is no justification for an absolute rest. Equal standards would demand to agree on a neutral point C in the middle between A and B.
Of course, if the distance between A and B is growing then A sees or hears the clock of B ticking slower if the temporal distance between two subsequent ticks is unchanged because light or sound, respectively, need an additional time of flight. This effect is named after Christian Doppler, and it is likewise valid for B seeing or hearing A.
Conversely, if the distance gets smaller, then the perceived frequencies increase. Both clocks observed from outside seem to run faster in this case. Such simple and compelling logic is broken if one adheres to the idea that A-related clocks can be attributed to all points in the coordinate system K while B-related clocks can be related to all points in the coordinate system k. All points means locations x between minus infinity and plus infinity. I consider just this idea the key mistake because it requires an overlap of past and future.
Einstein argued that the time in which light travels from A to B must be the same as the time required for returning from B to A: t_B - t_A = t'_A - t_B. Then he calculated the return distance 2 AB = (t'_A - t_A)c and concluded
r_AB = (t_B - t_A)(c-v) = (t'_A - t_B)(c+v). Accordingly he arrived at the well known paradox result: (c-v)(c+v) = c^2-v^2 does not depend on the sign of v. While the experimentally confirmed Doppler effect depends on the sign of relative motion, SR predicts a never measured length contraction regardless whether A and B move towards each other or away from each other. Because c-v is about twice as small as SQRT(c^2-v^2), the correct Doppler effect in case A and B move toward each other is about twice as large as the increase according to putative length contraction.
I agree with many experts: Einstein's synchronization by a thought measurement of light reflected from B return to A is unnecessary and led to many paradoxes.
A recent argument against curved spacetime gave evidence for a flat universe.
I should express gratitude towards those who did help me to clarify the matter, in particular Paul Davies. Peter Jackson and Thomas Ray guided me to heretical literature.
Regards,
Eckard
calls A also K and assumes it at rest. He calls B also k and ascribes to it a constant velocity v the direction of which coincides with positive x.