Speaker
Description
Our purpose is to give a step forward in the search of nature's options to describe classical gravity. Two reasonable hypotheses are invoked: the spacetime is described by a smooth manifold, which might or might not be Riemannian, and the classical gravitational dynamics is intimately related to the laws of thermodynamics (Jacobson's programme). We have found that the Einstein-Hilbert's action is the only one that may describe gravity in the Riemannian case whereas, in presence of torsion, an extra quadratic torsional term is needed (when the Lanczos-Lovelock requirements are also held). We have also found that the same strategy cannot be followed in the full non-Riemannian case as the two approaches are mutually inconsistent since the presence of non metricity forbids a thermodynamic equilibrium description.