# 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]}

*E*) can be calculated as the mass (

*m*) multiplied by the speed of light (

*c*= ~3×10

^{8}m/s) squared. Similarly, anything having energy exhibits a corresponding mass

*m*given by its energy

*E*divided by the speed of light squared

*c*

^{2}.

^{[1]}

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^{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.