Hamilton-Jacobi meet Mobius

Adaptation of the Hamilton-Jacobi formalism to quantum mechanics leads to a cocycle condition, which is invariant under D-dimensional Mobius transformations with Euclidean or Minkowski metrics. In this paper we aim to provide a pedagogical presentation of the proof of the Mobius symmetry underlying the cocycle condition. The Mobius symmetry implies energy quantization and undefinability of quantum trajectories, without assigning any prior interpretation to the wave function. As such, the Hamilton Jacobi formalism, augmented with the global Mobius symmetry, provides an alternative starting point, to the axiomatic probability interpretation of the wave function, for the formulation of quantum mechanics and the quantum spacetime. The Mobius symmetry can only be implemented consistently if spatial space is compact, and correspondingly if there exist a finite ultraviolet length scale. Evidence for non trivial space topology may exist in the cosmic microwave background radiation.