# mass-energy

*See also:*

**mass energy**

## EnglishEdit

### NounEdit

**mass-energy** (*countable and uncountable*, *plural* **mass-energies**)

- (physics) Mass and energy as a unified concept.
*Whereas in classical physics mass and energy are distinct concepts, on relativistic scales, they become indistiguishable and are replaced by***mass-energy**.*In higher-energy physics, mass and energy eventually become meaningless as individual concepts; a particle's so-called "mass" is actually*c**mass-energy**and is often given equivalently in units of either mass (GeV/^{2}) or energy (GeV).*For equations normalized with Planck units, the quantities of mass and energy become numerically identical, revealing their true nature as***mass-energy**.

- (also spelled mass energy) The energy associated with any given mass according to special relativity,
*E*=*mc*^{2}.

#### See alsoEdit

### AdjectiveEdit

**mass-energy** (*not comparable*)

- mass-to-energy
**Mass-energy**conversion occurs during nuclear fusion and fission.