Description of a rod with rigid, hyperbolic motion in the synchronous and the asynchronous formulation of relativistic dynamics

The synchronous and the asynchronous description of a rod with rigid hyperbolic motion are compared. It is shown that the covariant description, employing the energy-momentum four-vector, has an asynchronous character. The conclusion is that, in describing extended systems moving not too far from rigidly, the asynchronous formulation is more adequate than the synchronous formulation