What principle states that matter and energy may be converted, but there is never any net loss of total mass-energy?

The principle that states that matter and energy can be converted, but there is never any net loss of total mass-energy is best articulated through the concept of the Conservation of Mass Energy. This principle underscores that the total mass-energy in a closed system remains constant, even though it can change forms—transforming from mass to energy and vice versa. This concept is foundational in physics and is essential for understanding energy balance in various scenarios, including fire behavior.

While the Law of Conservation of Matter is similar, it primarily focuses on the preservation of mass alone, without considering the energy aspect. The Law of Energy Balance and the Principle of Matter Equivalence also address different aspects of physical principles and do not capture the full scope of the total mass-energy conservation. Understanding the Conservation of Mass Energy is crucial, especially in contexts such as combustion in firefighting, where energy changes and transformations play a significant role.