On the dual interpretation of zero-curvature Friedmann-Robertson-Walker models (Q2724821)

The starting point of this study is the remark that the energy-momentum tensor field of a spacetime, determined geometrically from the metric, has no a priori physical significance. On the same spacetime, this tensor field may be interpreted in several (conceptually different) ways. The authors consider a zero-curvature Robertson-Walker spacetime, whose (same) energy-momentum tensor arises from a perfect fluid flow or from a dissipative fluid. Moreover, necessary conditions are found for a transition from the first state to the second one, by passing through a specific ``critical point''.