Einstein's Elevator in Cosmology

The metrics of gravitational and cosmological models are brought into canonical form in comoving coordinates. The FWR curvature parameter k is read from this and it is shown that k=0 does not correlate to a flat model, but for a spatially positively curved geometry in which exist reference systems which are in free fall. This also corresponds to Einstein's elevator principle. Moreover, we show that our subluminal cosmos is associated with the Rn = ct model of Melia, assuming that k=0 is concerned to a free-falling system in the sense described above.