Recording Capacity and Macroscopic Entropy in Arborescent Eternalism

How can time have a physical direction if the whole history of the universe already exists? This paper gives a conditional account of temporal orientation through a rooted modal structure and its physical projection. Two complementary results establish the argument. Proposition 1 shows that a rule respecting exactly reversal-symmetric explanatory data cannot distinguish one time orientation from its reverse. Proposition 2 gives sufficient conditions for a rooted order of admissible event extensions to provide the required asymmetry. Its physical projection must yield at least one non-zero outgoing history-direction; every such direction must be timelike, and all must agree with one global orientation. That orientation is then uniquely compatible with the extension order on a connected, time-orientable spacetime. A Janus-style example shows how one global orientation can coexist with opposing local entropy arrows, and why the bridge fails when projected extensions demand opposite orientations. The contribution is an explicit connection between modal extension and physical orientation in a complete tenseless block. The extension order and projection are independently specified, and the result is conditional on their physical compatibility. Explaining thermodynamic irreversibility requires a further account of preparation and dynamics.