<p dir="ltr"><i>The Inverted Luminosity Hypothesis (ILH)</i> introduces a novel cosmological paradigm in which the Universe’s dark sector—comprising most of its mass-energy—is fully luminous within its own electromagnetic or analogous spectrum, yet invisible to baryonic observers due to orthogonal coupling. Luminosity is treated not as an intrinsic property of matter but as a relational outcome defined by emitter–detector interactions.</p><p dir="ltr">The <i>Inverted Luminosity Theorem</i> formalizes two perceptual manifolds, baryonic (Σᴮ) and dark (Σᴰ), whose near-zero overlap (Σᴮ ∩ Σᴰ ≈ ∅) yields reciprocal invisibility. Darkness therefore represents a deficit of coupling rather than an absence of light. Mechanistic realizations through hidden U(1) gauge symmetries, kinetic mixing, and topological segregation restore symmetry to cosmic composition, suggesting that each sector may view itself as radiant while perceiving the other as dark.</p><p dir="ltr">Empirical implications include gravitational-lensing anomalies, portal events, and haloscope detections of dark photons. The ILH reframes cosmic asymmetry as <i>reciprocal luminosity symmetry</i>—a Universe fully radiant yet partitioned by interaction geometry.</p><p dir="ltr">Developed by <b>Martin Thambi</b> in collaboration with AI systems (Grok – xAI, ChatGPT – OpenAI), the ILH exemplifies a new form of human–AI theoretical research linking cosmology, field theory, and philosophy into a unified perspective on visibility and perception.</p>