Physical Sciences

Relativity

1905

Intermediate

Mass-Energy Equivalence

E = mc^2

Mass and energy are equivalent—a tiny amount of mass contains enormous energy.

By Albert Einstein

Physical Sciences

1905 · Albert Einstein

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Story PortalWho discovered this?Discover how Albert Einstein and others shaped this equation.Visual PortalWhat does it look like?See the equation come alive in the Visual Studio.Machine PortalWhere is it used?Explore machines powered by this equation — nuclear reactors and PET scanners.Math PortalWhat does it derive from?Trace the mathematical lineage from special relativity.Future PortalWhere is it going?Fusion breakeven and cosmology

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Why it matters: Explained solar power, enabled nuclear energy, and transformed cosmology.

Discoverers: Albert Einstein (1905)

What does it mean?

Mass and energy are equivalent—a tiny amount of mass contains enormous energy.

Why should I care?

Explained solar power, enabled nuclear energy, and transformed cosmology.

Equation Compass

North — Prerequisites

West — History

Albert Einstein

East — Applications

South — Derivations

Derivation

Variables & Units

Symbol	Name	Unit	Meaning
$E$	Energy	J	Total energy
$m$	Mass	kg	Rest mass
$c$	Speed of light	—	299,792,458 m/s

Worked Example

1 kg mass ≡ 9×10¹⁶ J ≈ 21 megatons TNT equivalent.

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Energy Albert Einstein m E

Pictures & video

Portrait photograph of Albert Einstein, 1921 — Albert Einstein, 1921 — mass–energy equivalence followed from special relativity (1905).Ferdinand Schmutzer / Wikimedia Commons · Public domain

Sources & further reading

Mass–energy equivalence — Wikipedia Search Wikipedia Search Wolfram MathWorld Open in Wolfram|Alpha Watch explainers on YouTube

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