Tau does not flow through time — Tau IS the flow. There is no background clock ticking behind physical events. Remove all matter and you remove all time.
The arrow of time is the helical winding direction of the Tau standing wave — a geometric necessity, not a statistical accident. Entropy increase is a consequence, not the cause.
A precedes B if and only if A's Tau-address lies earlier in the helical wave than B's. Causation is not a primitive — it is derived from the geometry of Tau.
The present is the local Tau wave-front at a given Tau-address. The block universe is the global view; the present is the local view. Both are valid aspects of Tau.
Past-directed time travel is forbidden by dΣΤ = 0. Future-directed travel (faster Tau-rate at a local address) corresponds to relativistic time dilation in Tau terms.
Past Tau-addresses are encoded in the standing wave as phase information — real but causally inert. Future addresses are structurally determined but open in Tau-indeterminacy.