FormulaProved

Mass-energy equivalence

Statement

E = mc^2, the rest energy E of an object equals its rest mass m times the speed of light squared.

Why is it true?

Mass and energy are not two separately conserved quantities as in classical physics, but two faces of a single conserved quantity — this explains the enormous energy released in nuclear reactions.

A laser pulse absorbed by a body: absorbing energy E raises its mass by Δm = E/c² — far too small to weigh, yet it shapes nuclear physics.

Stated by

stated 1905Albert Einstein

Topics that use this theorem

Relativistic momentum and energy, E = mc²

Step-by-step proofs

Sketch of Einstein's argument for E = mc²

Albert Einstein (1905), trình bày lại, 1905

References

Albert Einstein (1905). Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig?