What Persists When Life Persists — Life as the Junction of Past and Future

This work is a short conceptual essay proposing a minimal physical definition of life.Life is described not as a material state or functional property, but as the capacity of a non-equilibrium open system to continuously update its boundary conditions, thereby maintaining a physical connection between past and future within the present.The essay extends this definition across multiple scales, from cellular and subcellular processes to individual organisms. At the level of the individual, memory and experience are interpreted as structures that configure boundary conditions toward the future, while psychological and physiological decline are examined as progressive losses of such updateability.This text is intended as a viewpoint complementing the author’s technical preprints, not as a comprehensive theory. It is offered as a stable conceptual reference point for future discussions on life, death, recovery, and temporal continuity in living systems.