determinism from periodic dynamics?
The standard meter in Paris and the Cesium atom are the operative definition of space and time in physics. The real difference between the definition of time and space is that, whereas you can move in space and compare a meter measured here with a miter measured there, you cannot move in time and you cannot compare a length of a second measured now and the length of a second measured yesterday. The only way to avoid this problem is to assume periodicity of isolated system as a fundamental principle together with a constant speed of light.
As proved in arXiv:0903.3680 the assumption of periodicity as a fundamental principle yields the remarkable possibility of a coherent and deterministic view of SR and QM.