Mass–energy equivalence
In physics, mass–energy equivalence is a concept formulated by Albert Einstein that explains the relationship between mass and energy. It expresses the law of equivalence of energy and mass using the formula
where E is the energy of a physical system, m is the mass of the system, and c is the speed of light in a vacuum (about 7008300000000000000♠3×10 m/s). In words, energy equals mass multiplied by the speed of light squared. Because the speed of light is a very large number in everyday units, the formula implies that any small amount of matter contains a very large amount of energy. Some of this energy may be released as heat and light by chemical or nuclear transformations. This also serves to convert units of mass to units of energy, no matter what system of measurement units used.