Z4DP IV: Hydrodynamic Interpretation of Redshift and the Nature of Stationary Macro-Space

This paper presents the fourth part of the Z4DP theoretical framework (Z4DP IV), which extends the superfluid vacuum model with a hydrodynamic interpretation of cosmological redshift. Unlike the standard model (ACDM), which interprets redshift as the metric expansion of space, Z4DP defines it as an exact measure of the fractional loss of propagation energy of a photon overcoming the hydrodynamic drag of the medium. Application of this analytical relationship to 1590 Type Ia supernovae from the Pantheon+ dataset shows a significantly higher statistical fit (_^20. 496) than the ACDM model (_^21. 049), without postulating dark energy. The theoretical framework is further robustly verified by independent cross-tests: it successfully predicts the Tolman surface brightness test and the Euclidean consistency of angular size, thereby eliminating the need for artificial galaxy evolution. Furthermore, it eliminates the critical time paradox of massive galaxy formation detected by the JWST and unifies the local gravitational redshift (Pound-Rebka experiment) with the cosmological one. Moreover, the thermodynamic nature of the model provides a direct explanation for the anisotropies of the cosmic microwave background (CMB-LSS cross-correlation) as local heating of the continuum in massive galaxy clusters. Thus, the 13. 8 billion year limit does not represent the Big Bang, but the absolute optical horizon of a stationary and non-expanding universe.