Mass–energy equivalence

physical law: mass and energy are proportionate measures of the same underlying property of an object

In physics, mass–energy equivalence is the principle that anything having mass has an equivalent amount of energy and vice versa, with these fundamental quantities directly relating to one another by Albert Einstein's famous formula:[1]

This formula states that the equivalent energy (E) can be calculated as the mass (m) multiplied by the speed of light (c = ~3×108 m/s) squared. Similarly, anything having energy exhibits a corresponding mass m given by its energy E divided by the speed of light squared c2.


  1. ^ a b Bodanis, David (2009). E=mc^2: A Biography of the World's Most Famous Equation (illustrated ed.). Bloomsbury Publishing. ISBN 978-0-8027-1821-1.