Which theory describes the relationship between mass and energy, stating that energy release results in mass loss?

The theory that describes the relationship between mass and energy, specifically detailing how energy release results in mass loss, is the theory of relativity, proposed by Albert Einstein. One of the key components of this theory is encapsulated in the famous equation (E=mc^2), which shows that energy (E) and mass (m) are interchangeable; they are different forms of the same entity. This means that under certain conditions, when energy is liberated from a system—such as during a nuclear reaction—there is a corresponding loss of mass.

In situations where mass is converted to energy, like in nuclear fission or fusion, a small amount of mass can be transformed into a significant amount of energy, illustrating how these concepts are fundamentally linked. This understanding has profound implications in both physics and chemistry, particularly in nuclear processes.

Other theories, like quantum theory, focus more on the behaviors of particles at very small scales, while string theory posits models of multiple dimensions and fundamental particles but does not specifically address the mass-energy equivalence. Nuclear theory primarily deals with the components and interactions of atomic nuclei but does not encapsulate the broader mass-energy relationship described by relativity. Thus, the theory of relativity stands out as the correct answer for