Bell's spaceship paradox --- reversed The "[URL [Broken] was discussed already https://www.physicsforums.com/showthread.php?t=236681", but I would like to add a twist. I take for granted, that the thread breaks, as described by Bell himself. Suppose the experiment starts out with a bit of slack on the thread connecting the two spaceships. Call the surrounding frame, the one that shall not move, S. Then, as described, rockets accelerate gently until the thread is taut, just before it breaks. Call the frame of the rockets S'. Now we play dumb and forget how the situation evolved. Rather, within S', we see just a taut thread between the rockets, which, from this frame's perspective don't move. Within S', an observer A', equidistant to both rockets starts the (seemingly original) Bell experiment, except, by coincidence, he orders the rockets to accelerate in reverse gear, as seen from S. Of course A' can expect the string to break. But: invoking our prior knowledge, we know that reverse gear actually means deceleration with S and the string should rather get some slack again. What's wrong here? My guess is as follows: Judged as seen from S, A' does not and can not order the rockets to accelerate synchronously. Rather they get orders in such a way that A' sees them synchronous, while within S they are not synchronous. Snap. Harald.