Einstein\'s New Ether 1916-1955
In 1905 A. Einstein banished the ether from physics in connection with the formulation of his Special Relativity Theory. This is very well known but less known is the fact that in 1916 he reintroduced the ether in connection with his General Relativity. He denominated it ?new ether? because, in opposition to the old one, the new one did not violate his Special and General Principle of Relativity. It didn\'t violate it because the new ether is not conceived as a privileged reference frame but it is considered as an ultra-referential primordial material reality which is not composed of points (or particles) and not divisible in parts and to which therefore the notions of motion and rest are not applicable. The purpose of this paper is to present a short outline of the history of Einstein\'s concepts on ether and to show which elements of the mathematical formalism of General Relativity were considered by Einstein as mathematical tools describing the relativistic ether, i.e. the ultra-referential space-time characterized with a certain kind of energy density. It will be indicated also that Einstein\'s intuitions and ideas concerning the ultra-referential space-time have to be investigated in the framework of Connes\' non-commutative geometry, as the commutative geometries are not sufficient to do it. In Poland Michal Heller and his colleagues are trying to create an unification of General Relativity and Quantum Mechanics with the help of Connes\' non-commutative geometry.