The Shockwave Expansion Hypothesis: A Boundary-Interaction Model for Accelerated Metric Expansion

This paper proposes a mechanical alternative to the standard cosmological model by recontextualizing accelerated cosmic expansion as a kinetic byproduct of our universe colliding with an external, high-density energy field. The model identifies the observable universe (roughly 5 percent of total mass-energy) as a stabilized internal payload, while the remaining 95 percent is defined as an "Active Hull" that functions as a boundary interface. By applying the principles of fluid dynamics to this boundary, the hypothesis unifies Dark Matter and Dark Energy as two properties of the same system: Dark Matter represents the mass and density of the Hull, while Dark Energy represents the kinetic recoil and pressure generated by the ongoing collision. This framework provides a potential resolution to major deadlocks in modern physics, such as the Hubble Tension and the Cosmological Constant Problem, by shifting the source of expansion from an internal vacuum to an external boundary interaction. The paper concludes with testable predictions regarding directional bias in expansion and large-scale cosmic wakes.