Cosmological Redshift from Local Metric Contraction: Implications for the Hubble Tension

We present an interpretation of cosmological redshift within the static‑substrate local‑perturbation paradigm. In this framework, redshift arises from continuous local metric contraction driven by substrate homeostatic self‑reversion, rather than from global spatial expansion. The perturbation bubble diffuses geometrically, but this diffusion does not directly produce redshift. The observed distance‑redshift relation emerges from the density‑dependent metric contraction rate. In the weak‑field, low‑density limit, the model reproduces the standard distance‑redshift relation, making it observationally equivalent to ΛCDM for all existing distance‑redshift data. This work does not claim to falsify ΛCDM at the observational level. It proposes an alternative ontological foundation for the same distance‑redshift data, with specific discriminative signatures that could distinguish the two frameworks in future experiments. The two frameworks differ in their ontological foundations and in specific testable signatures. We propose a thought experiment—we designate this thought experiment the flashlight redshift experiment—in which a laboratory light source propagates through a contracting metric. The static‑substrate framework predicts a tiny but non‑zero redshift, whereas ΛCDM predicts exactly zero. The framework further predicts an environment‑dependent Hubble gradient, which qualitatively resolves the Hubble tension. The quantitative construction of this gradient and its observational analysis are developed in a separate dedicated paper.