A Universal Survival–Absorption–Conversion Law Governing Energy Use and Growth in Living Systems

Living organisms are open, non-equilibrium thermodynamic systems that persist only by continuously absorbing energy and matter from their environment while exporting entropy in accordance with the second law of thermodynamics. Across all biological scales—from microorganisms to plants, insects, fish, animals, and humans—growth, reproduction, and functional productivity remain consistently far below theoretical energetic maxima. Empirical observations show that ecosystem-scale photosynthesis converts only ~1–3% of incident solar energy into biomass, animal metabolism allocates the majority of food energy to maintenance rather than growth or work, and biological productivity saturates even under increased resource supply. These persistent limits cannot be explained by classical efficiency metrics alone, which implicitly assume single-stage conversion and neglect transport losses, regulatory dissipation, and irreversible entropy production. Here we introduce a Universal Life Energy–Growth Framework that replaces idealized efficiency with a survival-based, systems-level formulation of biological energy use. Central to the framework is the energy survival factor Ψ=AE/TE+ε, where AE represents absorbed energy retained within the biological system boundary, TE denotes transport, regulatory, and environmental dissipation losses, and ε captures irreducible entropy-generating losses mandated by thermodynamic irreversibility. This formulation explicitly distinguishes energy conservation from exergy survival, enforcing the universal bound 0