Vacuum Energy and Quantum Gravity: A Pressure-Driven Gravity Perspective

This thesis investigates the long-standing discrepancy between quantum field theory (QFT) and cosmological observations of vacuum energy by proposing a novel framework based on Pressure-Driven Gravity (PDG). In this model, the vacuum is treated as a compressible quantum fluid—potentially a relativistic Bose-Einstein condensate (BEC)—whose pressure gradients govern gravitational behaviour. This approach offers a natural mechanism for renormalising vacuum energy, bridging the gap between quantum microphysics and macroscopic spacetime dynamics.The work develops a relativistic Lagrangian formalism for PDG, explores emergent gravitational effects via quantum pressure and proposes experimental tests using analogue gravity systems such as Rubidium-87 BECs. It also connects cosmological acceleration to vacuum rarefaction and introduces vacuum vortices as candidates for black hole analogues. By linking vacuum structure to gravitational phenomena without invoking a cosmological constant, this thesis contributes a testable and unified step toward quantum gravity.