Rethinking Cosmic Inflation Through Pressure-Driven Gravity: A Fluid-Dynamic Solution to the Horizon Problem

This thesis presents an alternative to scalar field inflation by modelling early universe expansion as a pressure-driven phenomenon within a relativistic, compressible vacuum medium. Rejecting the need for finely tuned inflation potentials or speculative scalar fields, this model proposes that rapid expansion arises from a rarefaction wave propagating through a vacuum Bose-Einstein condensate or similar medium. It successfully addresses the major unresolved issues of the standard cosmological model - including the horizon, flatness, and monopole problems—while also offering a natural pathway for baryogenesis via early pressure differentials and anisotropies. This framework bridges fluid dynamics, thermodynamics and quantum vacuum theory into a unified, testable paradigm that complements cosmic microwave background observations and early universe structure formation.