massaenergia

Mass-energy is a fundamental concept in physics describing the equivalence between mass and energy, as encapsulated by the theory of special relativity. It states that mass can be converted into energy and energy into mass, and that the total energy and momentum of a system are governed by a single relationship.

The most familiar form is Einstein’s equation E = mc^2, which relates rest mass m to rest energy E0 = m c^2, with c being the speed of light. For objects in motion, the total energy is E = γ m c^2, where γ is the Lorentz factor. A more general expression links energy, momentum p, and mass through E^2 = (pc)^2 + (m c^2)^2. These relations imply that even a stationary body possesses intrinsic energy, and that energy and mass can be interconverted under appropriate conditions.

Historically, the concept originated with Albert Einstein in 1905, within the development of special relativity and the understanding of electromagnetic radiation. It gained further support from experimental and theoretical advances in nuclear and particle physics, where measurable energy changes reflect mass changes. In nuclei, the binding energy accounts for the mass defect: the mass of a bound system is less than the sum of its constituents, with the difference converted to energy.

Mass-energy conservation is expressed through the conservation of the energy-momentum four-vector in relativistic physics. This principle underpins phenomena from nuclear fission and fusion to particle-antiparticle creation and annihilation, and it plays a central role in cosmology and high-energy physics.