Structural Differentiation Cosmology (SDC) Projection-Based Cosmic Acceleration: A Geometry–Growth Consistency Test

Structural Differentiation Cosmology (SDC) proposes an alternative interpretation of cosmic acceleration. In this framework the observed acceleration of the universe is not treated as a dynamical expansion driven by dark energy, but as an observational projection emerging from irreversible internal structural differentiation in an externally closed universe. The background expansion history remains nearly degenerate with ΛCDM, while the growth of structure exhibits a small but systematic deviation. A single geometry–growth consistency observable EG(z) is introduced to distinguish the SDC framework from the standard cosmological model. The cosmological constant in ΛCDM may therefore be interpreted as an effective phenomenological parameter arising from projection effects rather than a fundamental energy component. The framework is explicitly falsifiable through this observable relationship between geometry and structure growth. Version 1.6 introduces a minimal equation expressing the observational difference between SDC and ΛCDM and presents forecast detectability using current large-scale structure survey constraints.