We propose that photons propagate through space-time not by traversing the medium itself, but via transient, self-generated entropy-neutral tunnels. These pressure-free conduits allow photons to bypass gravitational curvature, entropy gradients, and fluid tension—preserving the constancy of the speed of light across all reference frames. Unlike massive objects, which displace the space-time fluid and generate curvature through persistent pressure gradients, photons form dynamically maintained, null-time tunnels that leave no trace or deformation in the surrounding medium. This model provides a mechanistic basis for null geodesic behavior, reconciling light-speed invariance with a compressible, thermodynamic fluid interpretation of space-time. It further explains the coherence, entanglement, and phase stability of photons in curved space-time by treating the tunnel interior as causally flat and entropy-isolated. We show how this tunneling structure parallels wormhole physics and aligns with the ER=EPR framework, suggesting a geometric origin for entanglement. Observable predictions include curvature-induced birefringence, quantized spectral phase shifts, and gravitational lensing anomalies—all of which are experimentally testable. This work advances a unified, fluid-dynamical description of light propagation, causal structure, and quantum coherence.