Simple thought experiment I read and would like to hear what others think will the result will be: Let two spaceships A and B accelerate along a straight line. Observer C does not accelerate. The accelerations, as judged by C, are constant for both ships. Each ship is equipped with a yard-arm, and a thread is tied between the two arms. Does the thread break, due to Lorentz contraction? (Assume that the acceleration is gentle enough that the thread does not break simply because of its own inertia).