Abstract This paper extends Einstein’s mass–energy equivalence principle, E = mc², into a conceptual form E = mc²(-L), where “-L” represents the invisible energetic loss associated with Life and Loss. The symbol highlights the often-overlooked “cost of life” in processes of material–energy transformation, while reflecting the phenomenon of “non-conservation of energy” within human society—where the total physical energy may appear constant, yet irreversible losses occur on social, ethical, and emotional levels, particularly during global crises such as the Covid-19 pandemic.