The entropic view of aging: from thermodynamics to biology

A growing body of evidence suggests that aging is not simply the accumulation of damage, but a systemic progression of increasing entropy across biological scales. Synthesizing concepts from thermodynamics and information theory, we propose a three-stage entropy model of the lifespan: order-building development, homeostatic adulthood, and disorder-dominant aging. Within this model, we reframe the established hallmarks of aging as interconnected nodes in an entropy-centered network and detail the multiscale manifestations of disorder from molecules to systems. To quantify this trajectory, we introduce a Multiscale Entropic Aging Index (MEAI) as a proof-of-concept conceptual framework, designed to integrate measurements of disorder across biological levels. This framework offers a potential unifying, quantitative language for aging research and positions entropy reduction as a testable mechanism underlying interventions, laying a principled foundation for the future development of biomarkers and rejuvenative strategies.