Which theory addresses the interactions between mass and energy at relativistic speeds?

The Theory of Special Relativity is the framework that deals specifically with the interactions between mass and energy at relativistic speeds, meaning speeds that are a significant fraction of the speed of light. Developed by Albert Einstein, this theory fundamentally changed our understanding of space and time, leading to the famous equation (E=mc^2), which quantifies the relationship between mass (m) and energy (E).

At relativistic speeds, the mass of an object effectively increases, which indicates that more energy is required to continue to accelerate it. This contrasts sharply with classical mechanics, which does not take into account the relativistic effects that become significant at high velocities.

The Theory of Universal Gravitation primarily focuses on the gravitational force exerted by masses, and while it does relate to the interplay between mass and gravitational energy, it does not address energy dynamics at relativistic velocities. Similarly, the Theory of Quantum Mechanics deals with the behavior of particles at very small scales, without directly addressing the relativistic relationship between speed, mass, and energy. Thus, the Theory of Special Relativity is uniquely positioned to describe the complex interactions of mass and energy at high speeds.