Spatial geometry of the rotating disk and its non-rotating counterpart

A general relativistic description of a disk rotating at constant angular velocity is given. It is argued that describing this situation using general relativity poses fewer conceptual problems than using special relativity. For observers on the disk, the geometry of their proper space is hyperbolic. This has interesting consequences concerning their interpretation of the geometry of a non-rotating disk with the same radius. The influence of clock synchronization on spatial measurements is discussed. (C) 2012 American Association of Physics Teachers. [http://dx.doi.org/10.1119/1.4730925]