What Does the Universe Expand Into?

This paper examines the ontological question of what the Universe expands into within the Scalar Drag Emergence Framework (SDEF). Building on the previously established ancestry-mediated expansion mechanism, it proposes that cosmological expansion advances into Potential, formally designated as the Vast Latent Coherent Potential (VLCP), mechanically represented through unparameterized timestamps. The paper develops the distinction between Potential, unparameterized timestamps, partial parameterization, and the decoherent expansion front. The advancing front carries accumulated ancestry and can only partially parameterize newly encountered timestamps, producing decoherent configurations. The subsequent emergence of coherence through recursive transport and corridor formation belongs to the established SDEF coherence ontology and is not rederived here. The paper also distinguishes the Observable Universe from the larger SDEF Universe, treating observational closure as a limit of direct access to coherent configurations rather than a boundary of the total Universe. This work is intentionally presented as an SDEF ontological position rather than a completed dynamical theory. It introduces no new expansion mechanism and does not claim to resolve the cosmological-constant problem. The proposed destination ontology remains subject to formal development, simulation, and observational testing.