According to Einstein’s Machian convictions, since inertia is determined only by matter, there can be no inertial structure or field in the absence of matter. Consequently, it is impossible, Einstein conjectured, to find a solution to the field equations—that is, to determine the metric \(g_{ij}\)—if the energy-momentum tensor \(T_{ij}\) representing the mass-energy content of the universe is zero. The non-existence of ‘vacuum solutions’ for a static universe demonstrated, Einstein thou