Final answer:
The law of conservation of energy asserts that the total amount of energy in an isolated system remains constant, even when accounting for the equivalence of mass and energy in relativistic physics.
Step-by-step explanation:
The property in question relates to the law of conservation of energy, which is a fundamental principle in physics. Energy can take various forms and can be transformed from one type to another, but the total energy within an isolated system remains constant. In the realm of classical physics, energy conservation is straightforward, but when considering relativistic effects, such as those observed in nuclear reactions, the definition of energy must include the equivalence of mass and energy. The first law of thermodynamics is a specific case of energy conservation, focused on the exchange of energy between a system and its surroundings through work and heat, reinforcing that the total internal energy of an isolated system remains unchanged.