We present the Space-Time Membrane (STM) model, which treats our four-dimensional spacetime as thesurface of an elastic membrane, with a mirror universe on the opposite side. Gravitational curvature correspondsto membrane deformation induced by energy external to the membrane, while homogeneous internal energydoes not produce curvature. Particles emerge as oscillatory excitations on the membrane’s surface, with theirmirror antiparticles on the far side. These oscillations modulate the membrane’s local elastic properties, yieldinggravitational and quantum-like phenomena. A modified elastic wave equation, incorporating tension, bendingstiffness, and space-time-dependent elastic variations, reproduces key features of General Relativity (GR) andaspects of Quantum Field Theory (QFT). Identifying strain fields with metric perturbations recovers equationsstructurally identical to the Einstein Field Equations. Time dilation, gravitational effects, and non-singular blackhole interiors arise naturally from these mechanics. Moreover, stable standing waves and controlled stiffnessvariations produce interference patterns and entanglement analogues, resembling quantum experiments withina deterministic, continuum framework. Interpreting photons as composite particle–antiparticle oscillationspreserves their masslessness, correct polarisations, U(1) gauge symmetry, and Lorentz invariance, consistentwith QFT. High-energy processes converting photons into particle pairs support this view. By adjusting anintrinsic coupling constant, time-averaged stiffness variations match observed vacuum energy, reproducing thecosmological constant. Furthermore, spatial variations in persistent wave energy may explain dark matter-likedistributions and address the Hubble tension. The STM model thus offers a geometric, deterministic approach tolinking particle-scale dynamics with cosmological phenomena, potentially resolving long-standing conceptualissues such as the black hole information loss paradox.