Release Message:  Inconsistencies related to the kinematics of a rigid, rotating disk.

Description:  The Ehrenfest paradox concerns the rotation of a "rigid" disc in the theory of relativity. In its original formulation as presented by Paul Ehrenfest 1909 in the Physikalische Zeitschrift,[1] it discusses an ideally rigid cylinder that is made to rotate about its axis of symmetry. The radius R as seen in the laboratory frame is always perpendicular to its motion and should therefore be equal to its value R0 when stationary. However, the circumference (2-R) should appear Lorentz-contracted to a smaller value than at rest, by the usual factor _. This leads to the contradiction that R=R0 and R<R0.