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It is common to think of our universe according to the "block universe"concept, which says that spacetime consists of many "stacked" 3-surfaces,labelled by some kind of proper time, $\tau$. Standard ideas do not distinguishpast and future, but Ellis "evolving block universe" tries to make afundamental distinction. One proposal for this proper time is the proper timemeasured along the timelike Ricci eigenlines, starting from the big bang. Thiswork investigates the shape of the "Ricci time" surfaces relative to the thenull surfaces. We use the Lemaitre-Tolman metric as our inhomogeneous spacetimemodel, and we find the necessary and sufficient conditions for these $\{\tau$=constant$\}$ surfaces, $S(\tau)$, to be spacelike or timelike. Furthermore, welook at the effect of strong gravity domains by determining the location oftimelike $S$ regions relative to apparent horizons. We find that constant Riccitime surfaces are always spacelike near the big bang, while at late times (nearthe crunch or the extreme far future), they are only timelike under specialcircumstances. At intermediate times, timelike $S$ regions are common unlessthe variation of the bang time is restricted. The regions where these surfacesbecome timelike are often adjacent to apparent horizons, but always outsidethem, and in particular timelike $S$ regions do not occur inside black holes.

Ricci Time in the Lemaitre-Tolman Model and the Block Universe