Hi all. Hoping someone can give me a brief explanation re: a problem I'm having in trying to understand SR. Not looking for an argument, and won't engage in one. Just seeking a few views on the following issue I'm having with understanding. In his 1905 paper on Special Relativity, Einstein says: "If one of two synchronous clocks at A is moved in a closed curve with constant velocity until it returns to A, the journey lasting t seconds, then by the clock which has remained at rest the travelled clock on its arrival at A will be 1/2tv2/c2 seconds slow. Thence we conclude that a balance-clock at the equator must go more slowly, by a very small amount, than a precisely similar clock situated at one of the poles under otherwise identical conditions." (Emphasis mine) I note that this was from Einstein's 1905 paper on Special Relativity, not his later work on General Relativity, which incorporates Special Relativity in whole, but in addition covers situations involving acceleration and gravity. Can anyone explain this to me: *The first postulate forces us to accept that there are no preferred reference frames (coordinate systems). The second postulate deals with he invariant nature of light velocity, irrespective of the motion of the source. *Given this, 1. *Why did Einstein predict that the polar clock, and not the equatorial clock, would be faster, since the polar clock is in exactly the same relative motion to the equatorial clock as the equatorial clock is to the polar clock. 2. *What justifies the assumption, obviously inherent in Einstein's prediction, that it is the equatorial clock that is moving slower than the polar clock? * 3. *How could we ever test such a proposition, since returning the clocks to a common point where a single observer could make the comparison would invoke acceleration of one or the other clock, thereby causing someone to claim that the system is now one not covered by SR? * This seems to me to be sort of an inherent inconsistency between the theory and the above prediction. *The theory (postulate 1) tells us that al motion in such a system is relative, and that the equatorial observer would measure the polar clock as slow, and vice versa. *Why, then, the conclusion that it is the polar clock that is fast? Thanks for any clarity you can add to my confusion.