This collection comprises four sequential papers that develop a unified conceptual model—the mirror system—in which a beam of light undergoes multiple reflections between two mirrors. By discretizing time into the number of round trips, encoding spacetime curvature into mirror geometry, and quantizing the mirrors themselves, the model provides a cross‑scale analogical framework spanning particle physics, quantum field theory, cosmology, thermodynamics, and quantum gravity. Paper 1 introduces the planar mirror system, simulating Feynman’s path integral, cosmological redshift, Hawking radiation, entropy increase, and Poincaré recurrence through frequency changes at each reflection. Paper 2 extends to curved mirrors (concave, convex, saddle), directly mapping mirror geometry to non‑Euclidean spacetimes, gravitational lensing, dynamical cosmic expansion, and an optical event horizon with greybody factors. Paper 3 quantizes the mirrors’ positions and curvatures, offering qualitative analogies of gravitational decoherence, the holographic principle, and the ER=EPR conjecture, while linking to tabletop experiments on gravity‑induced entanglement. Paper 4 synthesizes all three layers into a quantum field theory perspective, systematically mapping creation/annihilation operators, the dynamical Casimir effect, renormalization group flow, curved‑space QFT, and quantum gravity concepts within a single formal framework. Together, these papers demonstrate how a progressively liberated mirror system serves as an intuitive “poor man’s laboratory” for understanding and partially testing fundamental physics from flat spacetime to quantum geometry.