Accelerating spaceships paradox and physical meaning of length contraction

Abstract: A fifty-year old apparently paradoxical thought experiment involving two accelerating spaceships and a thread hat connects them states that the thread will break due to length contraction. This paradox still appears to be regarded by some physicists as a proof that (i) only physical bodies, but not space, undergo relativistic length contraction and (ii) a relativistically contracted body experiences a stress. This note, dedicated to the one hundredth anniversary of Hermann Minkowski's paper "Space and Time", shows that a proper relativistic treatment of the paradox demonstrates that it is a manifestation of a specific relativistic acceleration phenomenon, which does not have a classical analog. This means that length contraction plays no role in the resolution of the paradox. It is also shown that no stress is involved in the length contraction effect.