Impeded-Front Cosmogenesis: Phase-Transition Expansion in a Coherent Pre-Geometric Medium

We model the Big Bang as the propagation of a phase-transition front through
a pre-existing, phase-coherent medium characterized by a complex order parameter
Φ = √ρ eiϑ. Finite sound speed and bulk viscosity in this medium introduce a ma-
terial impedance to expansion, modifying the effective pressure according to peff =
p − 3ζH. This Coherent Impedance Pressure (CIP) alters early-universe dynamics rel-
ative to a perfect-fluid model. We derive the corresponding modification to curvature-
perturbation evolution, in which viscous damping suppresses short-wavelength modes
more strongly than long-wavelength modes. The framework predicts: (i) low-k suppres-
sion and mild oscillatory features in the matter power spectrum, (ii) partial preservation
of long-wavelength phase structure with possible signatures in low-ℓ CMB alignment,
and (iii) frequency-dependent propagation of primordial gravitational waves. These
signatures are testable with current and near-future surveys including DESI, Euclid,
CMB-S4, SKA, PTA networks, and LISA. The model provides an alternative to infla-
tionary and bounce scenarios while remaining observationally falsifiable. The coherence
pattern imprinted during the transition remains frozen into the fabric of spacetime,
forming the enduring structure of the observable universe