Emergence of FLRW Cosmology from Discrete Horizon Layering

We present a kinematic reconstruction in which a spatially flat FLRW interior emerges as the natural continuum description associated with a discretely growing, spherically symmetric horizon. The horizon is treated as a physically meaningful, information-bearing surface whose growth is organized by an explicit Planck-scale update rule: each completed incorporation increases the geometric mass parameter and the Schwarzschild radius by fixed increments. The construction does not assume a bulk stress–energy tensor and does not invoke the Einstein field equations. The interior geometry is reconstructed operationally from horizon data. The standard area–information relation assigns an increasing number of boundary degrees of freedom to successive horizon layers, while an information-limited stacking prescription maps the discrete update index to a continuous comoving radial coordinate. Early, small-area horizon layers therefore contribute coarse radial increments, while later layers provide progressively finer resolution, smoothing the dense Schwarzschild scaling and yielding a homogeneous continuum limit. Within this explicitly defined reconstruction class, homogeneity and isotropy are imposed as continuum symmetries of the coarse-grained interior. An operational stacking convention that identifies areal radius with accumulated proper radial depth uniquely selects the spatially flat representative of the FLRW family. Synchronization of horizon updates with a stretched-horizon proper-time parameter fixes the background expansion kinematically, leading to a coasting interior with a(t) ∝ t and H(t) ≃ 1/t at late times. The FLRW metric is thus not postulated but recovered as the appropriate continuum descriptor of discrete horizon growth and information-limited radial ordering. Effective fluid quantities, when introduced, are treated purely diagnostically and correspond to weff = −1/3 as a reparameterization of the resulting kinematics. The framework is intentionally agnostic about the microscopic realization of horizon degrees of freedom, relying only on spherical symmetry, the area–information relation, and null-synchronized horizon layering.