Pure shape dynamics: general framework

Abstract

Abstract We put forward a general framework for describing relational physical theories, which we call pure shape dynamics (PSD). Elaborating on the original insights brought about by the shape dynamics programme, PSD’s novel take on relationalism is its insistence on describing any dynamical system by means of the intrinsic geometry of its associated curve in the suitable relational configuration space of the theory, namely shape space, whereby the corresponding equation of state of the curve expresses the ratio of change of one of its geometric degrees of freedom with respect to another one. The mathematical structure underlying the equation of state is a local section over a natural generalisation of the unit tangent bundle, which we call shape phase space.