Mass-energy conservation states that mass and energy are interchangeable, as illustrated by nuclear fusion, where combined masses yield energy. The discussion highlights confusion regarding how gaining energy, such as potential energy while ascending in a lift, appears to increase mass. It clarifies that this perceived increase in mass is related to the work done to change energy states, aligning with the work-energy theorem. The conversation emphasizes that both special and general relativity explain these mass-energy relationships. Understanding these principles resolves the confusion about energy contributing to mass without implying the creation of matter.
